APITOXINA & ANTIBIOTICO
| Items 1 - 48 of 48 |
| 1: Antimicrob Agents Chemother. 2005 Oct;49(10):4085-92. |
Atomic force
microscopy study of the effect of antimicrobial peptides on the cell envelope
of Escherichia coli.
Meincken
M, Holroyd
DL, Rautenbach
M.
UNESCO Associated Centre for Macromolecules, Department of Chemistry,
The influences of the antibacterial magainin 2 and PGLa from the African clawed
frog (Xenopus laevis) and the hemolytic bee venom melittin on Escherichia
coli as the target cell were studied by atomic force microscopy (AFM). Nanometer-scale
images of the effects of the peptides on this gram-negative bacterium's cell
envelope were obtained in situ without the use of fixing agents. These high-resolution
AFM images of the surviving and intact target cells before and after peptide
treatment showed distinct changes in cell envelope morphology as a consequence
of peptide action. Although all three peptides are lytic to E. coli, it is
clear from this AFM study that each peptide causes distinct morphological
changes in the outer membrane and in some cases the inner membrane, probably
as a consequence of different mechanisms of action.
| 2: FEBS Lett. 2005 Mar 14;579(7):1658-64. |
Cross-presentation
of a CMV pp65 epitope by human dendritic cells using bee venom PLA2 as a membrane-binding
vector.
Babon A, Almunia C, Boccaccio C,
Beaumelle B,
Gelb MH, Menez A, Maillere B, Abastado JP,
Salcedo M, Gillet D.
Protein Engineering and Research
Department (DIEP), bat 152, CEA-Saclay, 91191 Gif sur Yvette cedex,
We have used bee venom phospholipase A2 as a vector to load human dendritic
cells ex vivo with a major histocompatibility complex (MHC) class I-restricted
epitope fused to its C-terminus. The fusion protein bound to human monocyte-derived
dendritic cells and was internalized into early endosomes. In vitro immunization
experiments showed that these dendritic cells were able to generate specific
CD8 T cell lines against the epitope carried by the fusion protein. Cross-presentation
did not require proteasome, transporter associated with antigen processing,
or endosome proteases, but required newly synthesized MHC molecules. Comparison
of the antigen presentation pathway observed in this study to that followed
by other toxins used as vectors is discussed.
| 3: Peptides. 2005 Feb;26(2):217-25. |
Conformation
and activity of delta-lysin and its analogs.
Dhople
VM, Nagaraj
R.
Centre for Cellular and Molecular Biology,
Delta-Lysin is a 26-residue hemolytic peptide secreted by Staphylococcus aureus.
Unlike the bee venom peptide melittin, delta-lysin does not exhibit antibacterial
activity. We have synthesized delta-lysin and several analogs wherein the
N-terminal residues of the toxin were sequentially deleted. The toxin has
three aspartic acids, four lysines and no prolines. Analogs were also generated
in which all the aspartic acids were replaced with lysines. A proline residue
was introduced in the native sequences as well as in the analogs where aspartic
acids were replaced with lysines. We observed that 20- and 22-residue peptides
corresponding to residues 7-26 and 5-26 of delta-lysin, respectively, had
greater hemolytic activity than the parent peptide. These shorter peptides,
unlike delta-lysin, did not self-associate to adopt alpha-helical conformation
in water, at lytic concentrations. Introduction of proline or substitution
of aspartic acids by lysines resulted in loss in propensity to adopt helical
conformation in water. When proline was introduced in the peptides corresponding
to the native toxin sequence, loss of hemolytic activity was observed. Substitution
of all the aspartic acids with lysines resulted in enhanced hemolytic activity
in all the analogs. However, when both proline and aspartic acid to lysine
changes were made, only antibacterial activity was observed in the shorter
peptides. Our investigations on delta-lysin and its analogs provide insights
into the positioning of anionic, cationic residues and proline in determining
hemolytic and antibacterial activities.
| 4: J Vet Sci. 2001 Aug;2(2):121-4. |
Therapeutic
effect of bee venom in sows with hypogalactia syndrome postpartum.
Choi
SH, Kang
SS.
Department of Veterinary Surgery, College of Veterinary Medicine and Research
Institute of Veterinary Medicine, Chungbuk National University, Cheongju 361-763,
Korea. shchoi@cbucc.chungbuk.ac.kr
The objective of this study was to determine the clincotherapeutic effect
of whole bee venom in hypogalactic sows postpartum. Sows after parturition
were assigned to treated and nontreated control groups. In the treated group,
22 sows were bee acupunctured once a day for 3 consecutive days. Honeybees
(Apis mellifera L.) for bee acupuncture were about 15 days after metamorphosis.
One live bee was used to sting the acupoints known as Yang-ming (ST-18,
PMID: 14614282 [PubMed - indexed for MEDLINE]
| 5: Am J Chin Med. 2003;31(1):149-55. |
Effect of
bee venom treatment in sows with oligogalactic syndrome postpartum.
Choi
SH, Kang
SS, Bae
CS, Cho
SK, Pak
SC.
The objective of this study was to determine the clinico-therapeutic effect
of worker honeybee venom in sows with oligogalactic syndrome postpartum. Comparison
between bee venom- and drug-treated groups was our main concern in the present
study. Sows after parturition were assigned to bee venom- and drug-treated
groups, respectively. In the bee venom-treated group, 22 sows were bee-acupunctured
once a day for 3 consecutive days. Honeybees (Apis mellifera L.) forbee acupuncture
were about 15 days old after metamorphosis. Live bees were used to sting the
acupoints known as yang-ming (ST-18,
PMID: 12723765 [PubMed - indexed for MEDLINE]
| 6: Antimicrob Agents Chemother. 2003 Mar;47(3):965-71. |
Modulation
of the activity of secretory phospholipase A2 by antimicrobial peptides.
Zhao
H, Kinnunen
PK.
Helsinki Biophysics & Biomembrane Group, Institute of Biomedicine, FIN-00014
The antimicrobial peptides magainin 2, indolicidin, and temporins B and L
were found to modulate the hydrolytic activity of secretory phospholipase
A(2) (sPLA(2)) from bee venom and in human lacrimal fluid. More specifically,
hydrolysis of phosphatidylcholine (PC) liposomes by bee venom sPLA(2) at 10
micro M Ca(2+) was attenuated by these peptides while augmented product formation
was observed in the presence of
| 7: Chembiochem. 2002 Jul 2;3(7):664-71. |
Erratum in:
· Chembiochem. 2002 Aug 29;3(8):687.
Molecular basis
of phospholipase A2 inhibition by petrosaspongiolide M.
Dal Piaz F, Casapullo A,
Randazzo A, Riccio R, Pucci P, Marino G, Gomez-Paloma L.
Dipartimento di Chimica Organica e Biochimica Universita di Napoli Federico
II via Cinthia 6, 80126 Napoli, Italy.
Petrosaspongiolide M (PM) is
an anti-inflammatory marine metabolite that displays a potent inhibitory activity
toward group II and III secretory phospholipase A(2) (PLA(2)) enzymes. The
details of the mechanism, which leads to a covalent adduct between PLA(2)
and gamma-hydroxybutenolide-containing molecules such as PM, are still a matter
of debate. In this paper the covalent binding of PM to bee venom PLA(2) has
been investigated by mass spectrometry and molecular modeling. The mass increment
observed for the PM-PLA(2) adduct is consistent with the formation of a Schiff
base by reaction of a PLA(2) amino group with the hemiacetal function (masked
aldehyde) at the C-25 atom of the PM gamma-hydroxybutenolide ring. Proteolysis
of the modified PLA(2) by the endoprotease LysC followed by HPLC MS analysis
allowed us to establish that the PLA(2) alpha-amino terminal group of the
Ile-1 residue was the only covalent binding site for PM. The stoichiometry
of the reaction between PM and PLA(2) was also monitored and results showed
that even with excess inhibitor, the prevalent product is a 1:1 (inhibitor:enzyme)
adduct, although a 2:1 adduct is present as a minor component. The 2:1 adduct
was also characterized, which showed that the second site of reaction is located
at the epsilon -amino group of the Lys-85 residue. Similar results in terms
of the reaction profile, mass increments, and location of the PLA(2) binding
site were obtained for manoalide, a paradigm for irreversible PLA(2) inhibitors,
which suggests that the present results may be considered of more general
interest within the field of anti-inflammatory sesterterpenes that contain
the gamma-hydroxybutenolide pharmacophore. Finally, a 3D model, constrained
by the above experimental results, was obtained by docking the inhibitor molecule
into the PLA(2) binding site through AFFINITY calculations. The model provides
an interesting insight into the PM-PLA(2) inhibition process and may prove
useful in the design of new anti-inflammatory agents that target PLA(2) secretory
enzymes.
PMID: 12325001 [PubMed - indexed for MEDLINE]
| 8: FEBS Lett. 1999 Apr 1;448(1):62-6. |
Biological
activities of C-terminal 15-residue synthetic fragment of melittin: design
of an analog with improved antibacterial activity.
Subbalakshmi
C, Nagaraj
R, Sitaram
N.
Centre for Cellular and Molecular Biology,
Melittin, the 26-residue predominant toxic peptide from bee venom, exhibits
potent antibacterial activity in addition to its hemolytic activity. The synthetic
peptide of 15 residues corresponding to its C-terminal end (MCF), which encompasses
its most amphiphilic segment, is now being shown to possess antibacterial
activity about 5-7 times less compared to that of melittin. MCF, however,
is 300 times less hemolytic. An analog of MCF, MCFA, in which two cationic
residues have been transpositioned to the N-terminal region from the C-terminal
region, exhibits antibacterial activity comparable to that of melittin, but
is only marginally more hemolytic than MCF. The biophysical properties of
the peptides, like folding and aggregation, correlate well with their biological
properties.
| 9: Yakugaku Zasshi. 1997 May;117(5):253-64. |
[Molecular action
mechanisms and membrane recognition of membrane-acting antimicrobial peptides]
[Article in Japanese]
Matsuzaki
K.
Faculty of Pharmaceutical Sciences,
A number of antimicrobial peptides have been isolated in the animal kingdom,
serving as defensive or offensive weapons. The mechanisms of their action
are considered to be the permeability of bacterial membranes, although the
details are not yet clarified. I have studied the interactions of several
antibiotic peptides with both artificial lipid bilayers and biomembranes to
elucidate the molecular mechanisms of the action and to find out the rationale
for their membrane specificity. Magainin 2 from the Xenopus skin was found
to form a peptide-lipid supramolecular complex pore in the membrane, followed
by peptide internalization, simultaneously dissipating the transmembrane potential
and the lipid asymmetry. This novel mechanism also works for a wasp bee venom,
mastoparan X. Tachyplesin I from Tachypleus and a bee venom, melittin, also
translocate across the membrane by forming a pore. The membrane selectivity
of these peptides is closely related to their affinity for the lipids constituting
the membrane surface. A strategy for developing a potent antibiotic was discussed
based on these results.
· Review
PMID: 9194394 [PubMed - indexed for MEDLINE]
| 10: Biochemistry. 1997 Feb 18;36(7):1826-35. |
Selective
lysis of bacteria but not mammalian cells by diastereomers of melittin: structure-function
study.
Oren
Z, Shai
Y.
Department of Membrane Research and Biophysics, Weizmann Institute of Science,
Studies on lipid-peptide interactions of cytolytic polypeptides tend to emphasize
the importance of the amphipathic alpha-helical structure for their cytolytic
activity. In this study, diasetereomers of the bee venom melittin (
| 11: Res Microbiol. 1997 Feb;148(2):163-75. |
Effect of
natural amphipathic peptides on viability, membrane potential, cell shape
and motility of mollicutes.
Beven
L, Wroblewski
H.
Groupe Membranes et Osmoregulation, UPRES-A CNRS Q6026, Universite de Rennes
1,
The antibiotic activity of ten amphipathic peptides was investigated in six
species of mollicutes belonging to the genera Acholeplasma, Mycoplasma and
Spiroplasma. A. laidlawii was the most sensitive and M. mycoides subsp. mycoides
SC the most resistant. Animal defence peptides (cecropins A and P1, and magainin
2) proved to be less potent than bee-venom mellitin and most of the peptides
produced by bacteria (globomycin, gramicidin S, surfactin and valinomycin)
or fungi (alamethicin). Gramicidin S was by far the most active peptide, with
minimal inhibitory concentrations ranging from 2 to 50 nM. Alamethicin, gramicidin
S, mellitin and surfactin had a cidal effect, whilst cecropins, globomycin,
magainin 2, polymyxin B and valinomycin proved to be static. The peptides
altered the membrane potential of spiroplasma cells with a potency independent
of their linear or cyclic structure. However, globomycin depolarized the plasma
membrane only weakly, whilst polymyxin B, in order to be active, required
prior hyperpolarization of the membrane. The peptides also induced the loss
of cell motility and helicity in spiroplasmas, suggesting that motility and
cell shape in these bacteria are coupled to the transmembrane electrochemical
gradient. Globomycin, an inhibitor of signal-peptidase II, prevented the growth
of spiroplasmas, M. gallisepticum, and M. genitalium, but not that of A. laidlawii
and M. mycoides subsp. mycoides SC, although the latter also synthesized membrane
lipoproteins. Inhibition of spiralin processing by globomycin was demonstrated
in S. citri and S. melliferum, with a more pronounced effect in the second
species.
| 12: J Steroid Biochem Mol Biol. 1997 Jan;60(1-2):51-7. |
Functional dissociation
between glucocorticoid-induced decrease in arachidonic acid release and inhibition
of adrenocorticotropic hormone secretion in AtT-20 corticotrophs.
Pompeo A, Luini A, Buccione R.
Istituto di Richerche Farmacologiche Mario Negri, Consorzio Mario Negri Sud,
Department of Cell Biology and Oncology, Chieti, Italy.
The biochemical basis of the
short-term inhibitory effects of glucocorticoids on corticotropin release
from pituitary corticotrophs is still obscure. A well-characterized effect
of glucocorticoids in several cell types is the inhibition of arachidonic
acid (AA) generation by phospholipase A2 (PLA2). Arachidonic acid and its
metabolites have been implicated in the secretory process from a number of
pituitary cells, such as the corticotrophs. We have thus examined the role
of AA in the anti-secretagogue effects of glucocorticoids in a corticotropin-secreting
clonal corticotroph line (AtT-20 D16/16). Glucocorticoids decreased AA release
induced by melittin, a bee venom protein related to extracellular PLA2. When
a possible role of AA in corticotropin release was studied, the following
results were obtained: (a) all corticotropin secretagogues tested, including
corticotropin-releasing factor (CRF), did not alter AA generation; (b) calcium
and guanine nucleotides, which stimulate corticotropin release in permeabilized
cells, inhibited the release of AA under the same conditions; (c) administration
of melittin or of exogenous AA had no effect on basal and CRF-stimulated corticotropin
release; (d) administration of large amounts of exogenous AA was unable to
restore the ability to secrete corticotropin under suppression by glucocorticoids.
Altogether, the data suggest that whereas glucocorticoids can inhibit both
AA generation and corticotropin release, these two effects appear to be causally
unrelated.
PMID: 9182858 [PubMed - indexed for MEDLINE]
| 13: Curr Microbiol. 1996 Nov;33(5):317-22. |
Inhibition
of spiralin processing by the lipopeptide antibiotic globomycin.
Beven L, Le Henaff M,
Fontenelle C,
Wroblewski H.
Equipe "Membranes et Osmoregulation," CNRS URA No. 256, Universite
de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex, France.
The cyclic lipopeptide globomycin,
a specific inhibitor of signal-peptidase II (Lsp A), proved toxic for the
mollicute Spiroplasma melliferum with a minimal inhibitory concentration (MIC)
in the range 6.25-12.5 microM, about one order of magnitude higher (that is,
less efficient) than bee-venom mellitin. SDS-PAGE analysis of cell proteins
followed by immunolabeling ("Western blotting") and by crossed immunoelectrophoresis
demonstrated that the cleavage of the prespiralin leader peptide was prevented
by globomycin. Cell fractionation experiments showed that prespiralin was
membrane bound and did not accumulate in the cytoplasm or in the culture medium.
Furthermore, the use of the potential-sensitive fluorescent dye 3,3'-dipropyl-2,2'-thiadicarbocyanine
iodide (diS-C3-[5]) revealed that, in contrast to valinomycin and mellitin,
globomycin up to 30 microM has no effect on the electrical transmembrane potential
of S. melliferum. This indicates that the toxicity of globomycin for spiroplasma
cells is mainly if not exclusively owing to the inhibition of spiralin processing.
Added to previously published data, these results suggest that spiralin and
probably other lipoproteins of mollicutes are acylated and membrane targeted
by a mechanism involving notably the processing of the prelipoprotein precursor
by a type II, globomycin-sensitive signal peptidase.
PMID: 8875913 [PubMed - indexed for MEDLINE]
| 14: Singapore Med J. 1996 Aug;37(4):389-91. |
Case reports and
mini review of bee stings of the cornea.
Chuah
G, Law
E, Chan
WK, Ang
CL.
Bee stings of the eye are not uncommon. Quite a few clinical case reports
have documented the various ocular reactions to the venom of the bee stings,
which may range from mild conjunctivitis to sudden loss of vision. This report
presents 2 patients who suffered bee stings to the cornea and their different
outcomes. The properties of bee venom as well as the treatment of various
possible complications are also discussed.
· Review
PMID: 8993139 [PubMed - indexed for MEDLINE]
| 15: Biochim Biophys Acta. 1994 Jul 21;1222(3):471-6. |
Melittin inhibits
epidermal growth factor-induced protein tyrosine phosphorylation: comparison
with phorbol myristate acetate and calcium ionophore A23187.
Errasfa
M, Stern
A.
Department of Pharmacology,
In HER14 cells, epidermal growth factor (EGF) induces tyrosine phosphorylation
of several proteins, including its own receptor. The bee venom peptide, melittin,
impaired EGF-dependent protein tyrosine phosphorylation in a calcium-dependent
manner. The melittin effect was similarly reproduced by calcium ionophore
A23187. The effect of melittin and calcium ionophore A23187 on EGF-dependent
protein tyrosine phosphorylation was abolished by treatment of cells with
the calcium chelator EGTA. Phorbol-myristate acetate (PMA) inhibited EGF-dependent
protein tyrosine phosphorylation, and when compared to melittin or calcium
ionophore A23187, only PMA potentiated the EGF-induced tyrosine phosphorylation
of two proteins immunologically related to mitogen activated protein (MAP)
kinases of 40 kDa and 44 kDa molecular mass. Unlike PMA, the effect of melittin
and calcium ionophore A23187 on inhibition of EGF-dependent protein tyrosine
phosphorylation was lost neither in protein kinase C-depleted cells nor in
cells treated with the protein tyrosine phosphatase inhibitors NaF and Na3VO4.
Melittin inhibited high affinity binding of EGF to its receptor in intact
cells, but this effect was not prevented by EGTA. It is concluded that melittin
and calcium ionophore A23187 differ from PMA in their inhibition of EGF-dependent
protein tyrosine phosphorylation in vivo, by acting via a Ca(2+)-dependent
pathway, that is independent of protein kinase C, protein tyrosine phosphatase
activity and high affinity binding of EGF to its receptor.
| 16: J Med Chem. 1993 Jun 25;36(13):1866-79. |
Molecular model
of the interaction of bee venom phospholipase A2 with manoalide.
Ortiz AR, Pisabarro MT,
Gago F.
Departamento de Fisiologia y Farmacologia, Universidad de Alcala de Henares,
Madrid, Spain.
A molecular model of the interaction
between manoalide (MLD) and bee venom phospholipase A2 (bv-PLA2) has been
derived making use of a combination of computational methods. MLD was built
in its open form and simulated by using molecular dynamics techniques. It
is shown that the polar part of the molecule, which is thought to be the reactive
region, is endowed with considerable conformational flexibility whereas the
apolar region is rather rigid. The proposed active conformation of MLD and
the main putative binding site for MLD on this enzyme were identified by matching
potential energy GRID maps for both ligand and receptor with the chemical
structure of the respective counterpart. The binding site is found in the
C-terminal region of bv-PLA2, forming part of the proposed interfacial surface
for binding to aggregated substrates, and comprises two distinct regions:
(i) a hydrophobic cavity delimited by the C-terminal beta-sheet and the antiparallel
beta-sheet, which interacts with the apolar zone of MLD, and (ii) a cationic
site made up of residues Arg-58 and Lys-94, which interacts with the polar
zone. Molecular dynamics and molecular orbital calculations indicate that
the most likely initial reaction between MLD and bv-PLA2 is formation of a
Schiff base between Lys-94 and the aldehyde generated upon opening of MLD's
gamma-lactone ring, supporting recent model reaction studies. The inhibition
seems to be a consequence of the occupation by MLD of a site overlapping a
phosphocholine binding site in bv-PLA2 presumably involved in the interface
desolvation process. The present model represents a starting point for further
structural studies on the mechanism of phospholipases A2 inactivation by MLD
and MLD-like compounds.
PMID: 8515424 [PubMed - indexed for MEDLINE]
| 17: Oncogene. 1993 Apr;8(4):939-47. |
Melittin-induced
hyperactivation of phospholipase A2 activity and calcium influx in ras-transformed
cells.
Sharma
SV.
Department of Microbiology and Immunology,
The activated ras oncogene is a key mediator of cellular transformation and
is present in a wide variety of primary human neoplasms. The biochemical role
of the ras oncogene in cellular transformation is at present unclear, and
hence approaches to control its activities in transformed cells have met with
limited success. Previous studies have demonstrated the ability of melittin,
a 26 amino acid amphipathic peptide from bee venom, to specifically counterselect
for cells in culture that express high levels of the ras oncogene product.
The biochemical basis for this counterselection is currently unknown. This
study demonstrates the ability of melittin to hyperactivate phospholipase
A2 (PLA2) in ras-transformed cells by the mediation of enhanced influx of
calcium ions (Ca2+). This hyperactivation of PLA2 and Ca2+ mobilization in
ras-transformed cells by melittin is mimicked by the calcium ionophore, A23187.
Both melittin- and A23187-mediated PLA2 hyperactivation require Ca2+. However,
the action of melittin is strongly dependent on extracellular Ca2+, whereas
that of A23187 is not. Melittin-induced Ca2+ influx and PLA2 hyperactivation
is inhibited by manganese ions (Mn2+). These studies reveal a close correlation
between the extent of PLA2 hyperactivation and Ca2+ mobilization, suggesting
a causal relationship.
| 18: Agents Actions. 1991 Sep;34(1-2):70-2. |
AGN
De Vries
GW, Lee
G, Amdahl
L, Wenzel
M, Garst
M, Wheeler
LA.
Department of Biological Sciences, Allergan, Inc.,
AGN 190383 is a 5-hydroxy-2(5H)-furanone ring analog of the marine natural
product manoalide. When applied topically, AGN 190383 inhibits phorbol ester
induced mouse ear edema. It is a potent inhibitor of bee venom phospholipase
A2 and blocks the release of arachidonic acid from calcium ionophore A23187
stimulated human neutrophils. AGN 190383 also inhibits both hormone-operated
and depolarization-dependent calcium mobilization in GH3 cells, as well as
fMLP stimulated increases in free cytosolic calcium in human PMNs. Furthermore,
it is also able to block the release of the neutral protease elastase from
stimulated neutrophils. The effects of AGN 190383 on arachidonic acid metabolism
and leukocyte function may account, in part, for its anti-inflammatory activity
in vivo.
| 19: Chem Phys Lipids. 1991 Mar;57(2-3):327-40. |
Polymorphic phospholipid
phase transitions as tools to understand peptide-lipid interactions.
Tournois
H, de Kruijff
B.
aATO Agrotechnology, Wageningen, The Netherlands.
The effect of peptides on bilayer----non-bilayer phase transitions can be
used as a tool to investigate the molecular aspects of peptide-lipid interactions.
In this contribution the action on membranes of the peptide antibiotic gramicidin
A and the bee venom component melittin are compared. Although the known structures
and locations of these peptides upon membrane binding are very different,
their actions on membranes show striking parallels. A general model is proposed
that explains the seemingly complex peptide-lipid interactions by making use
of simple concepts.
Publication Types:
· Review
PMID: 1711420 [PubMed - indexed for MEDLINE]
| 20: J Biol Chem. 1991 Feb 15;266(5):2753-8. |
Membrane
interactions of amphiphilic polypeptides mastoparan, melittin, polymyxin B,
and cardiotoxin. Differential inhibition of protein kinase C, Ca2+/calmodulin-dependent
protein kinase II and synaptosomal membrane Na,K-ATPase, and Na+ pump and
differentiation of HL60 cells.
Raynor
RL, Zheng
B, Kuo
JF.
Department of Pharmacology,
Interactions of certain naturally occurring, amphiphilic polypeptides with
membranes were investigated. Mastoparan (wasp venom toxin), melittin (bee
venom toxin), cardiotoxin (cobra venom toxin), and polymyxin B (antibacterial
antibiotic) inhibited protein kinase C stimulated by phosphatidylserine bilayer
or arachidonate monomer and blocked binding of [3H] phorbol 12,13-dibutyrate
to protein kinase C in the presence of phosphatidylserine bilayer, with IC50
values (concentrations causing 50% inhibition) of 1-8 microM. Mastoparan and
polymyxin B were much less inhibitory (IC50, 10-20 microM), whereas melittin
and cardiotoxin were similarly inhibitory (IC50, 1-4 microM), when protein
kinase C was activated instead by synaptosomal membrane. Kinetic analysis
indicate that mastoparan inhibited protein kinase C, assayed using phosphatidylserine
or synaptosomal membrane as the phospholipid cofactor, competitively with
the phospholipid cofactor, in a mixed manner with CaCl2 or diacylglycerol,
noncompetitively with histone, and uncompetitively with ATP, with apparent
Ki values of 1.6-18.7 microM. Inhibition of Na,K-ATPase in the membrane by
these polypeptides had relative potencies different from those for their inhibition
of protein kinase C activated by the same membrane preparation; mastoparan
and melittin inhibited the two activities with comparable potencies, but polymyxin
B and cardiotoxin were far less effective in inhibiting Na,K-ATPase. The same
relative inhibitory potencies of the polypeptides (melittin greater than mastoparan
greater than polymyxin B) for inhibition of Na,K-ATPase were also noted for
their inhibition of Ca2+/calmodulin-dependent protein kinase II, 86Rb uptake
(Na+ pump) by HL60 cells and the phorbol ester-induced differentiation of
the leukemia cells. These findings were consistent with discrete interactions
of the polypeptides with functionally distinct sites on the membrane, leading
to differential inhibition of biological activities associated with the membrane.
Actions of certain polypeptides appeared to be more specific compared to those
of lipid second messengers such as lyso-phosphatidylcholine and sphingosine,
and the antineoplastic ether lipid analogs such as 1-O-octadecyl-2-methyl-rac-glycero-3-ophosphocholine.
| 21: Infect Immun. 1990 Aug;58(8):2678-82. |
Effect of
staphylococcal delta-toxin and bee venom peptide melittin on leukotriene induction
and metabolism of human polymorphonuclear granulocytes.
Raulf
M, Alouf
JE, Konig
W.
Lehrstuhl fur Medizinische Mikrobiologie und Immunologie, Ruhr-Universitat
Bochum, Federal Republic of Germany.
The abilities of delta-toxin from Staphylococcus aureus and melittin to induce
and modulate the generation of leukotriene from human polymorphonuclear granulocytes
(PMNs) were studied. Stimulation of PMNs with melittin (10 micrograms) induced
leukotriene formation, whereas stimulation with delta-toxin did not. Preincubation
of the PMNs with delta-toxin modulated the subsequent generation of leukotriene
from PMNs induced by Ca ionophore A23187 or opsonized zymosan. The generation
of leukotriene B4 (LTB4), induced by the Ca ionophore A23187, was increased
when the PMNs were preincubated with delta-toxin for 5 min. When opsonized
zymosan was used as a secondary stimulus to activate the delta-toxin-pretreated
PMNs, LTB4 generation decreased. In contrast, melittin showed no significant
modulatory effect on the generation of leukotriene from PMNs. In addition,
preincubation of PMNs with delta-toxin inhibited the conversion of LTB4 to
omega-oxidation products. Our data suggest that peptides with similar structures,
e.g., delta-toxin and melittin, induce and modify leukotriene generation in
different manners.
PMID: 2164512 [PubMed - indexed for MEDLINE]
| 22: FEBS Lett. 1989 Dec 18;259(1):103-6. |
Antibacterial
and antimalarial properties of peptides that are cecropin-melittin hybrids.
Boman
HG, Wade
D, Boman
IA, Wahlin
B, Merrifield
RB.
Department of Microbiology,
Solid phase synthesis was used to produce 5 hybrid peptides containing sequences
from the antibacterial peptide, cecropin A, and from the bee venom toxin,
melittin. Four of these chimeric peptides showed good antibacterial activity
against representative Gram-negative and Gram-positive bacterial species.
The best hybrid, cecropin A(1-13)-melittin(1-13) was 100-fold more active
than cecropin A against Staphylococcus aureus. It was also a 10-fold better
antimalarial agent than cecropin B or magainin 2. Sheep red cells were lysed
by melittin at low concentrations, but not by the hybrid molecules, even at
50 times higher concentrations.
| 23: Zentralbl Bakteriol. 1989 Oct;271(4):521-31. |
Inhibition of in
vitro and in vivo mast cell degranulation by Taenia crassiceps metacestodes
in vitro incubation products.
Seifert
B, Geyer
E.
Fachbereich Biologie, Philipps-Universitat,
In vitro released products of T. crassiceps metacestodes (TcIP) harvested
from the peritoneal cavity of NMRI mice were tested for inhibitory effects
on the in vitro degranulation of peritoneal mast cells (MCs) of normal mice
(NMRI) and rats (Wistar) and on the in vivo degranulation of rat (Wistar)
skin MCs (PCA-assay). In vitro degranulation was elicited chemically (compound
48/80, polymyxin B or the bee venom peptide, mellitin). In vivo degranulation
was triggered immunologically (anaphylactic systems ovalbumin/anti-ovalbumin
or Fasciola hepatica crude fluke extract antigen/serum of fluke-infected rats
(Wistar]. In vitro degranulation of murine peritoneal MCs or the in vitro
histamine release of rat peritoneal MCs normally induced chemically was significantly
inhibited when the MCs were preincubated with the TcIP or with serum of T.
crassiceps-infected NMRI mice from day 35 post infection and thereafter. In
vitro degranulation of peritoneal MCs of infected mice was strongly inhibited
beginning on day 10 after infection. Also in vivo degranulation of the IgE-sensitized
rat skin MCs was significantly reduced by intradermal injection of the TcIP
before (6, 3 and 1 h) antigen challenge and by preinjection (1 h) of serum
from infected mice (day 80 p.i.)-The inhibitory effect was also demonstrated
after immunoadsorption of mouse serum proteins naturally contaminating the
TcIP. Heating (100 degrees C/15 min), even in the presence of
| 24: J Pharm Pharmacol. 1989 Jul;41(7):450-8. |
Inhibition of Na+,K+-ATPase
activity by phospholipase A2 and several lysophospholipids: possible role
of phospholipase A2 in noradrenaline release from cerebral cortical synaptosomes.
Nishikawa
T, Tomori
Y, Yamashita
S, Shimizu
S.
Department of Pharmacology,
p-Bromophenacyl bromide (PBPB), quinacrine and indomethacin, which inhibit
phospholipase A2 (PLA2; EC 3.1.1.4) activity in several tissues, caused a
dose-dependent inhibition of prelabelled [3H]noradrenaline ([3H]NA) release
evoked by high concentrations of K+ from rat cerebral cortical synaptosomes.
Release of prelabelled [3H]NA was caused by natural lysophosphatidic acid
(LPA; 10(-6)-10(-5) g mL-1) and lysophosphatidylcholine (LPC; 10(-6)-10(-5)
g mL-1) and synthetic LPA (6 x 10(-6), 2 x 10(-5) M) and LPC (6 x 10(-6),
2 x 10(-5) M), but not by natural lysophosphatidylserine (LPS; 10(-5) g mL-1),
lysophosphatidylethanolamine (LPE; 10(-5) g mL-1) and lysophosphatidylinositol
(LPI; 10(-5) g mL-1). The release evoked by natural LPA and LPC could be inhibited
only marginally by PBPB and quinacrine. Phosphatidic acid (PA)-specific and
phosphatidylcholine (PC)-specific PLA2 activities from rat cerebral cortical
synaptosomes were stimulated in incubation medium containing high concentrations
of K+ or calcium ionophore A23187. Low concentrations of PLA2 (10(-6)-10(-8)
g mL-1, from bee venom) inhibited the synaptic membrane Na+,K+-ATPase activity
in incubation media with intracellular levels of free Ca2+. Several lysophospholipids
(LPLs), metabolites of the PLA2 type, also inhibited the synaptic membrane
Na+,K+-ATPase activity in a dose-dependent manner. The minimum effective concentrations
of natural LPA, LPC, LPS, LPI and LPE were 10(-6), 4.7 x 10(-6), 10(-5), 4.7
x 10(-5) and 4.7 x 10(-5) g mL-1, respectively.(ABSTRACT TRUNCATED AT 250
WORDS)
PMID: 2570849 [PubMed - indexed for MEDLINE]
| 25: Biochem Pharmacol. 1988 Oct 1;37(19):3639-46. |
Inactivation of
phospholipase A2 by manoalide. Localization of the manoalide binding site
on bee venom phospholipase A2.
Glaser
KB, Vedvick
TS, Jacobs
RS.
Department of Biological Sciences,
The marine natural product manoalide (MLD), a potent inhibitor of phospholipases,
completely inactivates bee venom phospholipase A2 (PLA2) by an irreversible
mechanism. It has been proposed [K. B. Glaser and R. S. Jacobs, Biochem. Pharmac.
36, 2079 (1987)] that the reaction of MLD with PLA2 may involve the selective
reactivity of MLD to a peptide sequence, possibly a Lys-X-X-Lys peptide. Localization
of the MLD binding site on bee venom PLA2 demonstrated that upon MLD modification
of bee venom PLA2 the only change in amino acid content was an apparent loss
of Lys, corresponding to approximately three of the eleven
| 26: Biochem Pharmacol. 1987 Jul 1;36(13):2079-86. |
Inactivation of
bee venom phospholipase A2 by manoalide. A model based on the reactivity of
manoalide with amino acids and peptide sequences.
Glaser
KB, Jacobs
RS.
The marine natural product manoalide (MLD), a potent irreversible inhibitor
of bee venom phospholipase A2 (PLA2), was shown to produce a chromophore (lambda
max = 437 nm) during incubation with the enzyme. MLD also developed an identical
chromophore when incubated with free lysine (Lys), cysteine (Cys) or tryptophan
(Trp) but not with their N-alpha-amino-blocked analogs. These results suggest
that the chromophore product was dependent on the presence of two nucleophilic
groups which react by an ordered mechanism rather than by simple random collision.
Lys polymers prevented MLD from inhibiting PLA2, whereas monomeric Lys did
not. The optimal active polymer of Lys appeared to be a tetralysine (L4) peptide,
and a degree of selectivity was obtained when the Lys residues were in a 1,4-Lys
arrangement. The rate of chromophore development with PLA2 and the rate of
inactivation of PLA2 by MLD appear to be independent processes. Based on these
data, it is possible that the irreversible inactivation of PLA2 may involve
an ordered reaction with a peptide sequence in PLA2 containing a 1,4-Lys arrangement.
PMID: 3111475 [PubMed - indexed for MEDLINE]
| 27: Biochem Pharmacol. 1987 Mar 1;36(5):733-40. |
Differential effects
of manoalide on secreted and intracellular phospholipases.
Bennett
CF, Mong
S, Clarke
MA, Kruse
LI, Crooke
ST.
Manoalide, a novel nonsteroidal sesterterpenoid, is a potent inhibitor of
phospholipase A2 isolated from bee and cobra venoms. This report compares
the inhibition by manoalide of phospholipase A2 in crude cytosol fractions
from four mammalian tissues with that of four purified extracellular phospholipase
A2's. Phospholipase A2 isolated from bee venom (Apis mellifera) was the most
sensitive to inactivation by manoalide (IC50 approximately equal to 0.12 microM).
Extracellular phospholipase A2 from rattlesnake and cobra venom was intermediate
in sensitivity to manoalide (IC50 values of 0.7 and 1.9 microM respectively).
Porcine pancreatic phospholipase A2 was relatively resistant to inactivation
by manoalide (IC50 approximately equal to 30 microM). The phospholipase A2
assayed in crude cytosol fractions from four mammalian tissues exhibited IC50
values of 30 microM or greater. Cytosolic proteins as well as bovine serum
albumin and poly-L-lysine (Mr = 57,000) protected purified bee venom phospholipase
A2 from inactivation by manoalide. In contrast, amino acids such as lysine
and alanine failed to protect the purified enzyme from inactivation. Proteins
and certain amino acids, such as lysine, formed a chromogenic product when
incubated with manoalide. These data suggest that lysine is capable of reacting
with manoalide, but only when it is present in macromolecules is it capable
of protecting phospholipase A2 from inactivation by manoalide. Because cellular
proteins protect PLA2 from inactivation by manoalide, high concentrations
of manoalide must be applied topically to produce statistically significant
inactivation of intracellular phospholipase A2. Finally, a chemical model
is presented which explains the formation of a chromogenic product when manoalide
is incubated with proteins and amino acids.
PMID: 3103628 [PubMed - indexed for MEDLINE]
| 28: Arch Biochem Biophys. 1987 Feb 1;252(2):478-86. |
Mitogen-stimulated
release of inositol phosphates in human fibroblasts.
Jamieson
GA Jr, Villereal
ML.
Mitogenic stimulation of quiescent human fibroblasts (HSWP) with a growth
factor mixture (consisting of epidermal growth factor (EGF), insulin, bradykinin,
and vasopressin) rapidly induces an increase in Na influx via a Ca-mediated
activation of an amiloride-sensitive Na/H exchanger. Inositol phosphates (specifically
inositol-1',4',5'-phosphate) have been implicated in mediating the mobilization
of intracellular Ca stores in other cell types and we have now completed a
detailed analysis of the mitogen-induced release of inositol phosphates in
HSWP cells. Stimulation of inositol trisphosphate release is rapid (within
5 s) and reaches a maximum level (416-485% basal) within 10-15 s after the
addition of growth factor mixture. Inositol bisphosphate and inositol monophosphate
reach maximum levels by 30 s (1257% basal) and 60 s (291% basal), respectively.
Levels of all three compounds then decay toward basal levels but remain elevated
(150-350% of basal levels) after 10 min of incubation with mitogens. The effects
of different combinations of these growth factors and of the bee venom peptide,
melittin, have also been determined. We have also found that 8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate,
which prevents the mitogen-induced rise in intracellular calcium activity
and activation of Na influx, does not alter the mitogen-stimulated accumulation
of inositol trisphosphate. In addition, the calcium ionophore A23187, which
increases cytosolic Ca activity and induces a Na influx, does not stimulate
the release of inositol trisphosphate. Assays performed in the presence of
lithium, which inhibits inositol phosphate monophosphatase, promotes the prolonged
and enhanced accumulation of inositol monophosphate. Treatment with the phospholipase
inhibitor mepacrine or pretreatment with dexamethasone reduces the amount
of inositol phosphates released upon mitogenic stimulation. Hence mitogenic
stimulation of HSWP cells leads to the rapid stimulation of inositol phosphate
release via a calcium-independent mechanism and suggests inositol trisphosphate
as a candidate to mediate the release of intracellular calcium stores which
is involved in the processes responsible for the activation of the Na/H exchanger.
PMID: 3028268 [PubMed - indexed for MEDLINE]
| 29: Biochem Pharmacol. 1986 Feb 1;35(3):449-53. |
Molecular pharmacology
of manoalide. Inactivation of bee venom phospholipase A2.
Glaser
KB, Jacobs
RS.
The marine natural product manoalide (MLD) was shown to directly inactivate
bee venom phospholipase A2 (PLA2). Inactivation was pH dependent (maximum
inactivation occurred at pH 8.0), time dependent and concentration dependent.
The IC50 was estimated at 0.05 microM and virtually complete inactivation
of the enzyme occurred at 4.0 microM. The time-dependent loss of PLA2 activity
suggested that inactivation does not follow typical Michaelis-Menten kinetics.
Reversibility was studied directly by dilution and dialysis; both methods
were ineffective in dissociating the MLD-PLA2 complex. A kinetic plot of initial
velocity (v) versus [PLA2] supported our hypothesis that MLD apparently inactivates
bee venom PLA2 by an irreversible mechanism.
PMID: 3947381 [PubMed - indexed for MEDLINE]
| 30: Biochem Soc Symp. 1985;50:247-64. |
Cell damage by viruses,
toxins and complement: common features of pore-formation and its inhibition
by Ca2+.
Pasternak
CA, Alder
GM, Bashford
CL, Buckley
CD, Micklem
KJ, Patel
K.
Haemolytic paramyxoviruses interact with cells in the following way: a potentially
leaky viral envelope fuses with the plasma membrane, creating a hydrophilic
pore of approximately 1 nm in diameter; this allows ions and low molecular
weight compounds, but not proteins, to leak into and out of cells. Other viruses
act similarly if the pH is reduced to 5. Leakage (measured by collapse of
membrane potential, by movement of monovalent cations and by loss of phosphorylated
intermediates from cells) is prevented by extracellular Ca2+. Ca2+ does not
affect binding or fusion of virus to cells. It inhibits leakage as well as
preventing it, and it aids in the recovery (i.e. the restoration of non-leakiness)
of cells. Certain 'anti-Ca2+' drugs have an opposite effect. Experiments with
the bee venom protein melittin, with the alpha-toxin of Staphylococcus aureus
and with activated complement, show that the lesions produced by these agents,
too, are sensitive to extracellular Ca2+ and to 'anti-Ca2+' drugs. The
mechanisms of these effects are discussed.
Publication Types:
· Review
PMID: 3939403 [PubMed - indexed for MEDLINE]
| 31: Comp Biochem Physiol C. 1985;82(2):291-6. |
Melittin-induced
changes in Na and Cl movements across the skin and cornea (in vitro) of the
toad Bufo marinus.
McGahan
MC, Hazard
RL, Bentley
PJ.
Melittin, from bee venom, increases short-circuit current (Isc) across the
skin and cornea of toads. In skin this reflects a rise in the influx of Na
and is inhibited by meclofenamic acid (inhibits prostaglandin synthetase).
In corneas with melittin on the inside the rise in Isc is inhibited by bumetanide
(inhibits Cl transport) and meclofenamic acid. Melittin on the tear side of
the cornea causes a biphasic change in Isc, and a rise in all undirectional
fluxes of Na and Cl. This effect was not changed by bumetanide or meclofenamic
acid. Melittin apparently has two types of effects, one mediated by prostaglandins
while the other is more direct.
PMID: 2866902 [PubMed - indexed for MEDLINE]
| 32: Br J Pharmacol. 1984 Apr;81(4):693-701. |
A comparison of
histamine secretion from peritoneal mast cells of the rat and hamster.
Leung
KB, Pearce
FL.
Functional mast cells have been obtained by peritoneal lavage of the rat and
hamster. Both cell types released histamine on stimulation with appropriate
dilutions of anti-rat IgE and anti-hamster serum. The maximum response evoked
by each reagent was significantly greater for the hamster cells. The release
was non-cytotoxic and was in each case blocked by the corresponding soluble
antigen. The rat and hamster cells responded to concanavalin A and the lectin
from lentil. Phosphatidylserine (PS) potentiated the release only from the
rat cells. In the absence of the lipid, the hamster cells were more reactive.
The lectin from wheat germ, in the presence of PS, evoked histamine secretion
only from the rat cells. Both populations were refractory to the lectin from
soybean and to protein A. Rat peritoneal cells were more responsive to the
basic secretagogues compound 48/80 and peptide 401 (the MCD-peptide from bee
venom). These differences were less marked in the case of polylysine and polyarginine.
The two cell populations responded to the calcium ionophores A23187, ionomycin
and chlortetracycline. The hamster cells were significantly more sensitive
to the former two liberators but markedly less reactive to chlortetracycline.
Adenosine 5'-triphosphate (ATP) and dextran were potent histamine liberators
from the rat cells but were totally ineffective against the hamster. Acetylcholine
and carbamylcholine had no effect on either cell type. These results are discussed
in terms of the functional heterogeneity of mast cells from different sources.
PMID: 6202354 [PubMed - indexed for MEDLINE]
| 33: Biochim Biophys Acta. 1983 Dec 7;736(1):57-66. |
Changes in membrane
phospholipid distribution during platelet activation.
Bevers
EM, Comfurius
P, Zwaal
RF.
Exposure of phospholipids at the outer surface of activated and control platelets
was studied by incubation with a mixture of phospholipase A2 from Naja naja
and bee venom, solely or in combination with sphingomyelinase from Staphylococcus
aureus, using conditions under which cell lysis remained below 10%. Incubation
with phospholipase A2 alone revealed a markedly increased susceptibility of
the phospholipids in platelets activated by a mixture of collagen plus thrombin,
by the SH-oxidizing compound diamide, or by calcium ionophore A23187, as compared
to control platelets or platelets activated separately by collagen or thrombin.
Collagen plus thrombin, diamide, and ionophore treated platelets revealed
an increased exposure of phosphatidylserine at the outer surface accompanied
by a decreased exposure of sphingomyelin, as could be concluded from incubations
with a combination of phospholipase A2 and sphingomyelinase. These alterations
were much less apparent in platelets activated either by thrombin or by collagen
alone. The increased exposure of phosphatidylserine in activated platelets
is accompanied by an increased ability of the platelets to enhance the conversion
of prothrombin to thrombin by coagulation factor Xa, in the presence of factor
Va and calcium. It is concluded that the altered orientation of the phospholipids
in the plasma membrane of platelets activated by collagen plus thrombin, by
diamide, or by calcium ionophore, is the result of a transbilayer movement.
Moreover, the increased exposure of phosphatidylserine in platelets stimulated
by the combined action of collagen and thrombin might be of considerable importance
for the hemostatic process.
PMID: 6418205 [PubMed - indexed for MEDLINE]
| 34: FEBS Lett. 1983 Sep 5;161(1):41-4. |
Resistance
to apamin of the Ca2+-activated K+ permeability in pancreatic B-cells.
Lebrun
P, Atwater
I, Claret
M, Malaisse
WJ, Herchuelz
A.
The bee venom neurotoxin apamin failed to affect 86Rb outflow and insulin
release from rat pancreatic islets stimulated by D-glucose or the Ca2+-ionophore
A23187. Apamin, in contrast to quinine or A23187, also failed to affect bioelectrical
activity in mouse islet cells. These findings suggest that, like in erythrocytes,
and at variance with the situation found in smooth muscle, liver or neuroblastoma
cells, the Ca2+-activated K+ permeability in the pancreatic B-cell is resistant
to apamin.
PMID: 6411494 [PubMed - indexed for MEDLINE]
| 35: Biochim Biophys Acta. 1983 Jan 5;727(1):108-14. |
Melittin and a chemically
modified trichotoxin form alamethicin-type multi-state pores.
Hanke
W, Methfessel
C, Wilmsen
HU, Katz
E, Jung
G, Boheim
G.
The bee venom constituent, melittin, is structurally and functionally related
to alamethicin. By forming solvent-free planar bilayers of small area (approx.
100 microns 2) on the tip of fire-polished glass pipettes we could observe
single melittin pores in these membranes. An increase in the applied voltage
induced further non-integral conductance levels. This indicates that melittin
forms multi-level pores similar to those formed by alamethicin. Trichotoxin
A40, an antibiotic analogue of alamethicin, also induces a voltage-dependent
bilayer conductivity, but no stable pore states are resolved. However, chemical
modification of the C-terminal molecule part by introduction of a dansyl group
leads to a steeper voltage-dependence and pore state stabilization. Comparing
structure and activity of several natural and synthetic amphiphilic polypeptides,
we conclude that a lipophilic, N-terminal alpha-helical part of adequate length
(dipole moment) and a large enough hydrophilic, C-terminal region are sufficient
prerequisites for voltage-dependent formation of multi-state pores.
PMID: 6824646 [PubMed - indexed for MEDLINE]
| 36: Adv Exp Med Biol. 1983;156:553-67. |
Influence of aprotinin
and gabexate mesilate on arachidonic acid release by the Ca-ionophore A
Seeger
W, Wolf
H, Graubert
E, Moser
U, Neuhof
H, Roka
L.
In a model of isolated, ventilated rabbit lungs, perfused with Krebs-Henseleit
albumin buffer in a recirculating system, increased availability of free AA
(arachidonic acid) results in an increase in pulmonary vascular resistance
and permeability. The former can be ascribed to cyclooxygenase products of
AA, among which thromboxane A2 is mainly responsible. The increase of vascular
permeability is, at least partly, due to lipoxygenase products of AA. Availability
of free AA for the different oxygenation pathways can be achieved either by
direct application of free AA to the perfusion fluid or by stimulation of
AA release from the membrane phospholipid pool by the Ca-ionophore A 23187.
The serine proteinase inhibitor gebaxate mesilate in a concentration range
between 1 microM and 10 microM and aprotinin in a concentration range between
8 and 200 KIE/ml dose-dependently reduce the increase in vascular resistance
after stimulation with A 23187. Correspondingly the increase in vascular permeability
due to A 23187 is significantly reduced by gabexate mesilate (5 microM) to
52% and by aprotinin (200 KIE/ml) to 73%. On the contrary the increase in
pulmonary vascular resistance and permeability after direct application of
free AA to the perfusion fluid is not affected by gabexate mesilate and aprotinin.
AA metabolism by cyclooxygenase from ram vesicular gland microsomes is inhibited
in vitro by gabexate mesilate and by aprotinin only in very high concentrations
(greater than 1mM respectively greater than 2130 KIE/ml). Measurements with
porcine pancreas and bee venom phospholipase A2 reveal no influence of aprotinin
on these enzymes. Gabexate mesilate inhibits pancreas phospholipase A2 in
concentrations more than 10-fold higher than those necessary in the isolated
lungs (IC50 = 430 microM), bee venom phospholipase A2 not being affected at
all. It is thus apparent that the release of AA from the membrane phospholipid
pool rather than any particular step in its oxygenation metabolism is the
site of action of these proteinase inhibitors in the pulmonary vascular bed.
The possible involvement of an intracellular proteinase is discussed.
PMID: 6190378 [PubMed - indexed for MEDLINE]
| 37: J Immunol. 1982 Jun;128(6):2481-6. |
Mucosal mast
cells. II. Effects of anti-allergic compounds on histamine secretion by isolated
intestinal mast cells.
Pearce
FL, Befus
AD, Gauldie
J, Bienenstock
J.
Functional mast cells have been isolated from the lamina propria of the small
intestine of rats infected with the nematode Nippostrongylus brasiliensis.
The cells released histamine on challenge with specific antigen, anti-rat
IgE, concanavalin A, and calcium ionophores but were less responsive than
peritoneal mast cells (MMC) from the same animals. Intestinal mucosa mast
cells (PMC) were refractory to the action of the basic secretagogues peptide
401 from bee venom and compound 48/80. The anti-allergic compounds disodium
cromoglycate (less than or equal to 10(-3) M), AH 9679 (less than or equal
to 10(-4) M), and theophylline (less than or equal to 10(-2)) did not inhibit
antigen-induced histamine secretion by MMC, although these compounds were
effective against PMC. In contrast, doxantrazole (10(-5) to 10(-3) M) inhibited
the secretion of histamine from both MMC and PMC in a comparable dose-dependent
fashion. Thus, we have established that mast cells from different sites are
functionally heterogeneous not only in their response to various stimuli for
histamine secretion, but also in their responses to different pharmacologic
modulators of secretion. It cannot be assumed that anti-allergic compounds
effective against mast cells in one tissue site or organ will be equally efficacious
against mast cells in other sites. The extent of this functional heterogeneity
must be established, and its investigation may provide new insights into the
biochemical events involved in mast cell secretion.
PMID: 6176639 [PubMed - indexed for MEDLINE]
| 38: J Physiol. 1981 Aug;317:67-90. |
Effects of quinine
and apamin on the calcium-dependent potassium permeability of mammalian hepatocytes
and red cells.
Burgess
GM, Claret
M, Jenkinson
DH.
1. K-sensitive electrodes placed in the extracellular fluid have been used
to show that ATP and noradrenaline cause a rapid loss of up to 10% of the
K content of isolated guinea-pig hepatocytes. 2. The hypothesis tha this response
is a consequence of a rise in the K permeability of the hepatocyte membrane
triggered by an increase in cytosolic Ca is supported by the finding that
the divalent cation ionophore A23187 also initiated K loss, in this instance
of up to 20-25% of the amount in the cells. 3. Under similar conditions A23187
caused a transient increase, followed by a larger decrease, in the 45Ca content
of guinea-pig hepatocytes equilibrated with this isotope. The decrease alone
was seen with ATP and noradrenaline. 4. Quinine (
| 39: Nature. 1981 Jul 16;292(5820):246-8. |
Sequence and specificity
of two antibacterial proteins involved in insect immunity.
Steiner
H, Hultmark
D, Engstrom
A, Bennich
H, Boman
HG.
Immune responses have been described for many different insect species. However,
it is generally acknowledged that immune systems must therefore differ from
those of vertebrates. An effective humoral immune response has been found
in pupae of the cecropia moth, Hyalophora cecropia. The expression of this
multicomponent system requires de novo synthesis of RNA and proteins and its
broad antibacterial activity is due to at least three independent mechanisms,
the most well known of which is the insect lysozyme. However, this enzyme
is bactericidal for only a limited number of Gram-positive bacteria. WE recently
purified and characterized P9A and P9B, which are two small, basic proteins
with potent antibacterial activity against Escherichia coli and several other
Gram-negative bacteria. We believe that P9A and P9B plays an important part
in the humoral immune responses described previously and that the P9 proteins
represent a new class of antibacterial agents for which we propose the name
cecropins. We describe here the primary structures of cecropins A and B. We
also show that cecropin A is specific for bacteria in contrast to melittin,
the main lytic component in bee venom which lyses both bacteria and eukaryotic
cells.
PMID: 7019715 [PubMed - indexed for MEDLINE]
| 40: Biokhimiia. 1980 Oct;45(10):1840-9. |
[Effects of melittin
and its tetraacetyl derivative on rat liver mitochondria]
[Article in Russian]
Shol'ts
KF, Reznik
GI, Solov'eva
NA, Shezhkova
LG, Miroshnikov
AI.
The uncoupling effect of melittin, the principal peptide of bee venom was
studied. It was found that the activation of mitochondrial respiration by
melittin and its derivative is due to the formation of channels equally penetrable
for lithium, sodium, potassium and rubidium ions. The penetrability of the
inner mitochondrial membrane appears at melittin or tetraacetyl melittin concentrations
about 0.90 or 0.15 nmol/mg of protein, respectively. The appreciable increase
of the uncoupling activity of melittin under blocking of its amino groups
suggests that these groups are not very essential for the channel formation.
In contrast to gramicidin S and similar to gramicidin A, the effect of melittin
develops in time. The lag in the effects of melittin and its derivative indicates
that the slow rearrangement stage precedes the formation of channels in the
membrane. It is suggested that the effects of melittin are due to the formation
of multimolecular complexes of the peptide with phosphatides of the inner
mitochondrial membrane.
PMID: 6165401 [PubMed - indexed for MEDLINE]
| 41: Biochim Biophys Acta. 1979 Sep 12;570(1):198-209. |
Effect of alamethicin,
gramicidin S and melittin upon the particulate guanylate cyclase from rat
lung.
Lad
PJ, White
AA.
The channel-forming antibiotic alamethicin activated rat lung particulate
guanylate cyclase (GTP pyrophosphate-lyase (cyclizing) EC 4.6.1.2), and the
activated enzyme was further stimulated by sodium nitroprusside when a thiol
such as 2-mercaptoethanol was present. Similar effects were seen with the
antibiotic gramicidin S and with melittin, a polypeptide purified from bee
venom. All of these agents are amphiphilic polypeptides. Nitroprusside was
not able to stimulate both particulate and soluble enzyme treated with the
nonionic amphiphile, Lubrol PX, suggesting that the membrane-active polypeptides
had a different mechanism of action. These polypeptides are known to alter
the membrane matrix by binding to phospholipid, and we suggest that this alteration
allowed greater access of substrate and of nitroprusside to the enzyme. Lubrol
PX, however, may interact preferentially with the enzyme, and thus block nitroprusside
activation. The most potent of these agents was melittin, which stimulated
nitroprusside activation at a concentration which had little effect by itself
(7 microns), and at which others have demonstrated lytic effects on cells.
PMID: 90524 [PubMed - indexed for MEDLINE]
| 42: Med Biol. 1976 Feb;54(1):39-49. |
Cytotoxic effects
on the plasma membrane of human diploid fibroblasts--a comparative study of
leakage tests.
Thelestam
M, Mollby
R.
Confluent monolayers of human diploid lung fibroblasts were treated with cytolytic
agents. The induced membrane damage was investigated by different test systems.
Changes of membrane permeability were compared with morphological alterations.
Four tests employed leakage of cytoplasmic markers of different sizes as criteria
of membrane damage. Radioactive markers of the following decreasing size order
were used: [3H]RNA (MW greater than 200,000) greater than 51Cr greater than
[3H]nucleotides greater than [1-14C]alpha-amino-isobutyric acid (AIB, MW 103).
Uptake of trypan blue was employed as a fifth criterior of changed membrane
permeability. A comparison between the tests indicated the following order
of sensitivity for detection of membrane damage: leakage of AIB-label greater
than leakage of nucleotide label greater than leakage of 51Cr-label=uptake
of trypan blue= morphological changes greater than leakage of RNA-label. Two
distinct types of leakage patterns were evident: 1. Upon incubation with Triton
X-100 all four release curves coincided. This was considered as representing
large functional "holes". 2. With the polyene amphotericin B the
smallest marker (AIB) was released to a strikingly greater extent than other
markers. This was regarded as representing very small functional "holes".
Melittin from bee venom and theta-toxin from Clostridium perfringens induced
leakage patterns of two intermediate types. The results indicate that a combination
of several different size markers may be useful for characterizing induced
membrane lesions.
PMID: 1263610 [PubMed - indexed for MEDLINE]
| 43: Infect Immun. 1975 Aug;12(2):225-32. |
Sensitive
assay for detection of toxin-induced damage to the cytoplasmic membrane of
human diploid fibroblasts.
Thelestam
M, Mollby
R.
A sensitive assay was developed for detection and quantitation of subtle permeability
changes in the cytoplasmic membrane of human diploid fibroblasts. Release
of the non-metabolizable amino acid [1-14C]alpha-aminoisobutyric acid (AIB;
molecular weight (103) from the cytoplasm of prelabeled cells was used as
an indicator of toxin-induced membrane damage. An optimal procedure for labeling
these cells was designed after varying the conditions with regard to pH, temperature,
concentration of AIB, composition of medium, and incubation time. Toxin-induced
release of AIB was compared with release of a previously described nucleotide
label, [3H]uridine. Melittin from bee venom and the polyene antibiotics filipin
and amphotericin B in low concentrations induced a strikingly greater release
of AIB than of nucleotide label. The sensitivity of this assay was furthermore
demonstrated by treatment with the following bacterial cytolysins: phospholipase
C and theta-toxin from Clostridium perfringens, alpha-, beta-, delta-, and
gamma-toxins from Staphylococcus aureus, and streptolysin S from Streptococcus
pyogenes. In spite of their different modes of action, all these membrane-active
toxins at low concentrations induced a significant release of AIB label. For
an equal release of nucleotide label, several times higher concentrations
were required.
PMID: 169201 [PubMed - indexed for MEDLINE]
| 44: Infect Immun. 1975 Apr;11(4):640-8. |
Determination
of toxin-induced leakage of different-size nucleotides through the plasma
membrane of human diploid fibroblasts.
Thelestam
M, Mollby
R.
Human diploid lung fibroblasts were treated with cytolytic bacterial toxins
and the nature of the membrane damage was investigated. [3H] uridine was used
for differential labeling of cytoplasmic components of small or large molecular
size. Two principal size categories were achieved by labeling the fibroblasts
in either early growth phase or stationary phase, a high-molecular weight
ribonucleic acid label and a low-molecular-weight nucleotide label. The size
of the labeled molecules was determined by perchloric acid precipitation and
gel chromatography. Leakage of labeled molecules of different size indicated
the size of the "functional pores" in the plasma membrane caused
by the test substance. The nonionic detergent Triton X-100 produced large
functional pores in the fibroblast membrane as evidenced by rapid leakage
of both large and small labeled molecules. Theta-toxin from Clostridium perfringens
and the polyene antibiotic filipin both gave rise to considerably small functional
pores in the plasma membrane. Although small molecules easily passed the treated
membrane, large molecules could not escape from the cells even after prolonged
treatment with these substances or by increasing their concentration. By the
contrast, the leakage profiles obtained with melittin from bee venom or with
delta-toxin from Staphylococcus aureus in each case suggested the formation
initially of pores of intermediate size that increased upon prolonged incubation
or when higher concentrations were used.
PMID: 164404 [PubMed - indexed for MEDLINE]
| 45: FEBS Lett. 1974 Sep 15;46(1):141-4. |
Enhancement of bee
venom phospholipase A2 activity by melittin, direct lytic factor from cobra
venom and polymyxin B.
Mollay C, Kreil G.
PMID: 4371280 [PubMed - indexed for MEDLINE]
| 46: Z Naturforsch B. 1969 Feb;24(2):263. |
[On the biological
activity of the bee venom melittin]
[Article in German]
Jentsch
J.
PMID: 4388835 [PubMed - indexed for MEDLINE]
| 47: Proc Soc Exp Biol Med. 1968 Mar;127(3):707-10. |
Antibacterial action
of melittin, a polypeptide from bee venom.
Fennell
JF, Shipman
WH, Cole
LJ.
PMID: 4870538 [PubMed - indexed for MEDLINE]
| 48: Res Dev Tech Rep. 1967 Dec 5;:1-13. |
Antibacterial action
of a bee venom fraction (melittin) against a penicillin-resistant staphylococcus
and other microorganisms. USNRDL-TR-67-101.
Fennell
JF, Shipman
WH, Cole
LJ.
PMID: 5300771 [PubMed - indexed for MEDLINE]