Major proteins of bovine seminal plasma inhibit phospholipase A2

We have recently shown that the major proteins of bovine seminal plasma, namely BSP-A1, BSP-A2, BSP-A3 and BSP-30-kDa (collectively called BSP proteins) bind to spermatozoa and that the binding sites on the plasma membrane of spermatozoa are choline phospholipids. In view of the fact that these phospholipids are substrates for phospholipase A2 (PLA2), a key enzyme in sperm capacitation and the acrosome reaction, the effect of BSP proteins on this enzyme activity was investigated. Since these BSP proteins are ubiquitous, the effect on pig pancreatic PLA2 was also studied. In contrast with control proteins, when preincubated with phosphatidylcholine as substrate, all BSP proteins inhibited both pancreatic and sperm PLA2 activity in a dose-dependent manner and in the presence of 1-6 microM BSP protein the enzyme activity was completely abolished. When phosphatidylethanolamine was used as substrate, only pancreatic PLA2 was inhibited. On the other hand, when the BSP proteins were preincubated with the enzyme followed by addition of substrate, a biphasic effect was observed; there was stimulation of enzyme activity below 1.3 microM BSP followed by an inhibition above this concentration. The inhibitory activity was trypsin-sensitive but heat-resistant. The effect of co-incubation of heparin, which is implicated in sperm capacitation and which also interacts with BSP proteins, was studied. Heparin (10 microM) had no effect on the PLA2 inhibitory activity exhibited by all BSP proteins. The PLA2 inhibitory effect exhibited by BSP proteins was abolished with excess substrate. The BSP proteins were adsorbed on PLA2-agarose and could be affinity cross-linked to the enzyme, indicating a direct interaction of enzyme with the inhibitor. These results suggest that these BSP proteins modulate PLA2 activity and therefore, phospholipid metabolism.

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Interaction of plant lipids with 14 kDa phospholipase A2 enzymes

Biochemical Journal ◽

10.1042/bj3200093 ◽

1996 ◽

Vol 320 (1) ◽

pp. 93-99 ◽

Cited By ~ 18

Author(s):

Bannikuppe S VISHWANATH ◽

Waldemar EICHENBERGER ◽

Felix J FREY ◽

Brigitte M. FREY

Keyword(s):

Enzyme Activity ◽

Phospholipase A2 ◽

Fatty Acyl ◽

Polar Head Group ◽

Dependent Manner ◽

Pla2 Activity ◽

Group I ◽

Plant Lipids ◽

Acyl Chains ◽

Dose Dependent

Several structurally related plant lipids were isolated and their effect was assessed on the enzyme activity of group I (pancreatic and Naja mocambique venom) and group II (Crotalus atrox venom) phospholipase A2 (PLA2) enzymes, with labelled Escherichia coli as an enzyme substrate. The neutral monogalactosyldiacylglycerol (MGDG) and negatively charged diacylglyceryl α-D-glucuronide (DGGA) did not influence the enzyme activity of either group. Digalactosyldiacylglycerol (DGDG), another uncharged glycolipid, inhibited PLA2 activity in a dose-dependent manner to 60–70% of the control. Sulphoquinovosyldiacylglycerol (SQDG), which is also anionic, activated both groups of PLA2 enzyme. A similar activation was observed with the zwitterionic diacylglyceryl-O-(N,N,N-trimethylhomoserine) (DGTS) and diacylglyceryl-O-(hydroxymethyl)(N,N,N-trimethyl)-β-alanine (DGTA). DGDG, SQDG and DGTS are dispersed homogeneously with low critical micelle concentrations (CMCs). The hydrodynamic radius of neutral DGDG is an order of magnitude larger than the charged lipids SQDG and DGTS. The inhibition of pig pancreatic PLA2 by DGDG was dependent on substrate concentration. The intrinsic fluorescence spectra of the enzyme was not changed in the presence of native or hydrogenated DGDG. Thus the inhibition is most probably due to a non-specific interaction of plant lipids with the substrate. Different lengths and saturations of the fatty acyl chains of DGDG did not alter the inhibition of PLA2, whereas deacylation abrogated the inhibitory effect. Both SQDG and DGTS activated pig pancreatic PLA2 in a dose-dependent manner. Saturation of the double bonds of these lipids decreased the activating effect. The fluorescence of pig pancreatic PLA2 incubated with SQDG and DGTS was enhanced by 2-fold and 3-fold respectively, suggesting the formation of a complex between enzyme and lipids. In conclusion, the effect of different plant lipids on PLA2 activity depends on different structural elements of the polar head group and their charge as well as the degree of unsaturation of the fatty acyl chains.

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Phenolic Acids from Lycium barbarum Leaves: In Vitro and In Silico Studies of the Inhibitory Activity against Porcine Pancreatic α-Amylase

Processes ◽

10.3390/pr8111388 ◽

2020 ◽

Vol 8 (11) ◽

pp. 1388

Author(s):

Luna Pollini ◽

Alessandra Riccio ◽

Cristina Juan ◽

Carmela Tringaniello ◽

Federica Ianni ◽

...

Keyword(s):

Phenolic Acids ◽

Inhibitory Activity ◽

Leaf Extract ◽

Inhibitory Effect ◽

Dependent Manner ◽

Lycium Barbarum ◽

Plant Materials ◽

Vitro Assay ◽

In Silico Studies

Nowadays, bioactive compounds from vegetable food and waste are of great interest for their inhibitory potential against digestive enzymes. In the present study, the inhibitory activity of methanolic extract from Lycium barbarum leaves on porcine pancreas α-amylase has been studied. The α-amylase inhibitory activity of the constituent phenolic acids was also investigated. The leaves were extracted by ultrasound-assisted method, one of the most efficient techniques for bioactive extraction from plant materials, and then the phenolic acids were identified by Accurate-Mass Quadrupole Time-of-Flight (Q-TOF) Liquid Chromatography/Mass Spectrometry (LC/MS). Chlorogenic and salicylic acids were the most abundant phenolic acids in L. barbarum leaf extract. The inhibitory effect against α-amylase, determined for individual compounds by in vitro assay, was higher for chlorogenic, salicylic, and caffeic acids. L. barbarum leaf extract showed an appreciable α-amylase inhibitory effect in a concentration-dependent manner. Docking studies of the considered phenolic acids into the active site of α-amylase suggested a conserved binding mode that is mainly stabilized through H-bonds and π-π stacking interactions.

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Collagenase inhibition by water-pepper (Polygonum hydropiper L.) sprout extract

Journal of Herbmed Pharmacology ◽

10.15171/jhp.2019.18 ◽

2019 ◽

Vol 8 (2) ◽

pp. 114-119 ◽

Cited By ~ 1

Author(s):

Tomoaki Kawaguchi ◽

Kaori Nagata

Keyword(s):

Column Chromatography ◽

Inhibitory Activity ◽

High Performance ◽

Inhibitory Effect ◽

Skin Aging ◽

Dependent Manner ◽

Dermal Matrix ◽

Polygonum Hydropiper ◽

Concentration Dependent Manner ◽

Hplc Fraction

Introduction: Collagenase plays an important role in the degradation of dermal matrix proteins leading to wrinkle formation. The objectives of this study were to evaluate the inhibitory effect of water-pepper (Polygonum hydropiper L.) sprout extract on the activity of collagenase and to identify the inhibitory compounds.Methods: Collagenase inhibitory activity was measured by spectrophotometric assay. Activity-guided fractionation was performed using liquid-liquid extraction of water and n-butanol and Diaion HP-20 column chromatography, followed by high-performance liquid chromatography (HPLC) fraction collection.Results: A methanolic extract of water-pepper sprout inhibited collagenase activity in a concentration-dependent manner with an IC50 value of 156.7 μg/mL. Collagenase inhibitory activity (IC50 = 23.5 μg/mL) was found in 50% methanol eluate from the HP-20 column chromatography of the n-butanol soluble fraction. The active compound (IC50 = 1.9 μg/mL) in the eluate was isolated by HPLC and identified as quercetin-3-O-galactoside (hyperoside) from comparing retention time, UV-Vis absorption, and mass spectra with those of the standard. Lineweaver-Burk plots revealed that hyperoside was an uncompetitive inhibitor against collagenase. Hyperoside was also the most abundant flavonoid present in the methanolic extract.Conclusion: These results suggest that water-pepper sprouts could be beneficial as a natural source of collagenase inhibitor which might be used for the treatment of skin aging.

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Effects of bivalent cations on prostaglandin biosynthesis and phospholipase A2 activation in rabbit kidney medulla slices

Biochemical Journal ◽

10.1042/bj1820821 ◽

1979 ◽

Vol 182 (3) ◽

pp. 821-825 ◽

Cited By ~ 17

Author(s):

A Erman ◽

A Raz

Keyword(s):

Arachidonic Acid ◽

Linoleic Acid ◽

Prostaglandin E2 ◽

Phospholipase A2 ◽

Inhibitory Effect ◽

Rabbit Kidney ◽

Dependent Manner ◽

Kidney Medulla ◽

Bivalent Cations ◽

Tissue Lipids

The bivalent cations Ca2+, Mg2+, Co2+, Mn2+, Sr2+ and Ba2+ were compared for their stimulatory or inhibitory effect on prostaglandin formation in rabbit kidney medulla slices. Ca2+, Mn2+ and Sr2+ ions stimulated prostaglandin generation up to 3–5-fold in a time- and dose-dependent manner (Ca2+ greater than Mn2+ congruent to Sr2+). The stimulation by Mn2+ (but not by Sr2+) was also observed in incubations of medulla slices in the presence of Ca2+. Mg2+ and Co2+ ions were without significant effects on either basal or Ca2+-stimulated prostaglandin synthesis. The stimulatory effects of Ca2+, Mn2+ and Sr2+ on medullary generation of prostaglandin E2 were found to correlate with their stimulatory effects on the release of arachidonic acid and linoleic acid from tissue lipids. The release of other fatty acids was unaffected, except for a small increase in oleic acid release. As both arachidonic acid and linoleic acid are predominantly found in the 2-position of the glycerol moiety of phospholipids, the stimulation by these cations of prostaglandin E2 formation appears to be mediated via stimulation of phospholipase A2 activity.

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Biosynthesis of platelet-activating factor (PAF) in human polymorphonuclear leucocytes. The role of lyso-PAF disposal and free arachidonic acid

Biochemical Journal ◽

10.1042/bj2680091 ◽

1990 ◽

Vol 268 (1) ◽

pp. 91-98 ◽

Cited By ~ 18

Author(s):

M D C Garcia ◽

S Fernandez-Gallardo ◽

M A Gijon ◽

C Garcia ◽

M L Nieto ◽

...

Keyword(s):

Fatty Acids ◽

Arachidonic Acid ◽

Phospholipase A2 ◽

Platelet Activating Factor ◽

Inhibitory Effect ◽

Eicosatetraenoic Acid ◽

Polymorphonuclear Leucocytes ◽

Maximal Effect ◽

Dependent Manner ◽

Dose Dependent

Theophylline and 1-methyl-3-isobutylxanthine (MIX), compounds that block eicosanoid formation and modulate phospholipase A2 activity, inhibited in a dose-dependent manner the formation of both leukotriene B4 (LTB4) and platelet-activating factor (PAF) by human polymorphonuclear leucocytes (PMN) in response to ionophore A23187. Theophylline and MIX lacked any inhibitory effect on acetyl-CoA: lyso-PAF acetyltransferase activity, which is the rate-limiting step for PAF biosynthesis in PMN. The effect of theophylline and MIX on PAF formation could be reversed by incubating the cells in the presence of 1-10 microM exogenous lyso-PAF. Incubation of PMN homogenates in the presence of unsaturated non-esterified fatty acids resulted in dose-dependent inhibition of the acetyltransferase. This effect was linked to the presence of a free carboxyl group, since both arachidonic acid methyl ester and palmitoyl-arachidonoyl phosphatidylcholine lacked inhibitory activity. This inhibitory effect was also dependent on the number of double bonds, since arachidonic acid (C20:4) and eicosapentaenoic acid (C20:5) displayed maximal effect. Kinetic analysis showed that the effect of arachidonic acid was consistent with competitive inhibition, with a Ki value of about 19 microM. Oxidative metabolites of arachidonic acid showed a lesser inhibitory effect with the following order of potency: arachidonic acid greater than 15-HETE (15-hydroxy-6,8,11,14-eicosatetraenoic acid) greater than LTB4 greater than 5-HETE (5-hydroxy-6,8,11,14-eicosatetraenoic acid) greater than lipoxin A4. Examination of enzymes involved in CoA-dependent acylation revealed a low activity of both arachidonoyl-CoA synthetase and arachidonoyl-CoA: lyso-PAF arachidonoyltransferase. These data indicate a strong influence on PAF biosynthesis of the products of the phospholipase A2 reaction, with lyso-PAF disposal being a critical event for PAF formation, and unsaturated fatty acids acting as feed-back inhibitors. The conversion of arachidonic acid via oxidative metabolism into less active inhibitors of acetyl-CoA:lyso-PAF acetyltransferase seems to be an additional mechanism of modulation of this enzyme activity, linked to the function of lipoxygenases. Finally, the enzyme activities involved in arachidonoyl-CoA-dependent acylation of lyso-PAF show a low efficiency in capturing arachidonic acid.

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HBV Pre-S1-Derived Myristoylated Peptide (Myr47): Identification of the Inhibitory Activity on the Cellular Uptake of Lipid Nanoparticles

Viruses ◽

10.3390/v13050929 ◽

2021 ◽

Vol 13 (5) ◽

pp. 929

Author(s):

Masaya Nanahara ◽

Ya-Ting Chang ◽

Masaharu Somiya ◽

Shun’ichi Kuroda

Keyword(s):

Amino Acid ◽

Cellular Uptake ◽

Inhibitory Activity ◽

Sodium Taurocholate ◽

Lipid Nanoparticles ◽

Inhibitory Effect ◽

Amino Acid Sequences ◽

Hbv Infection ◽

Dependent Manner ◽

Independent Manner

The Myr47 lipopeptide, consisting of hepatitis B virus (HBV) pre-S1 domain (myristoylated 2–48 peptide), is an effective commercialized anti-HBV drug that prevents the interaction of HBV with sodium taurocholate cotransporting polypeptide (NTCP) on human hepatocytes, an activity which requires both N-myristoylation residue and specific amino acid sequences. We recently reported that Myr47 reduces the cellular uptake of HBV surface antigen (HBsAg, subviral particle of HBV) in the absence of NTCP expression. In this study, we analyzed how Myr47 reduces the cellular uptake of lipid nanoparticles (including liposomes (LPs) and HBsAg) without NTCP expression. By using Myr47 mutants lacking the HBV infection inhibitory activity, they could reduce the cellular uptake of LPs in an N-myristoylation-dependent manner and an amino acid sequence-independent manner, not only in human liver-derived cells but also in human non-liver-derived cells. Moreover, Myr47 and its mutants could reduce the interaction of LPs with apolipoprotein E3 (ApoE3) in an N-myristoylation-dependent manner regardless of their amino acid sequences. From these results, lipopeptides are generally anchored by inserting their myristoyl residue into the lipid bilayer and can inhibit the interaction of LPs/HBsAg with apolipoprotein, thereby reducing the cellular uptake of LPs/HBsAg. Similarly, Myr47 would interact with HBV, inhibiting the uptake of HBV into human hepatic cells, while the inhibitory effect of Myr47 may be secondary to its ability to protect against HBV infection.

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Influence of arachidonic acid on indices of phospholipase A2 activity in the human neutrophil

Biochemical Journal ◽

10.1042/bj2910825 ◽

1993 ◽

Vol 291 (3) ◽

pp. 825-831 ◽

Cited By ~ 23

Author(s):

J D Winkler ◽

C M Sung ◽

W C Hubbard ◽

F H Chilton

Keyword(s):

Fatty Acids ◽

Arachidonic Acid ◽

Protein Kinase ◽

Phospholipase A2 ◽

Human Neutrophils ◽

Maximal Effect ◽

Dependent Manner ◽

Pla2 Activity ◽

Tetraenoic Acid ◽

Stimulation Of

The present studies were conducted to understand better the regulation of phospholipase A2 (PLA2)-dependent mobilization of lipid mediators by arachidonic acid (C20:4). After stimulation of human neutrophils, g.l.c./m.s. analysis of non-esterified fatty acids indicated that the quantity of C20:4 increased as a function of time after stimulation, from undetectable quantities to > 800 pmol/10(7) cells. In contrast with C20:4, the quantities of other free fatty acids such as oleic and linoleic were high in resting cells and did not change after stimulation. Some 15% of the C20:4 released from cellular lipids remained cell-associated. To examine the effect of C20:4 on its own release, neutrophils were exposed to [2H8]C20:4, to differentiate it by g.l.c./m.s. from naturally occurring C20:4. In A23187-stimulated neutrophils, low concentrations (5-10 microM) of [2H8]C20:4 added just before A23187 increased the quantity of C20:4 produced by the cell, whereas higher concentrations (30-50 microM) decreased the quantity of C20:4 released from phospholipids. As other measures of PLA2 activity, the effects of C20:4 on production of platelet-activity factor (PAF) and leukotriene B4 (LTB4) were assessed. C20:4 treatment just before stimulation of neutrophils blocked PAF and LTB4 production in a concentration-dependent manner (IC50 10-20 microM). The effect of C20:4 was not blocked by the cyclo-oxygenase inhibitor naproxine (10 microM), nor could it be mimicked by 1 microM LTB4, 5-hydroxyeicosa-6,8,11,14-tetraenoic acid (5HETE), 5-hydroperoxyeicosa-6,8,11,14-tetraenoic acid (5HPETE) or 15-hydroxyeicosa-5,8,11,13-tetraenoic acid (15HETE). The 5-lipoxygenase (5LO) inhibitor zileuton induced a concentration-dependent decrease in PAF, with a maximal effect of a 50% decrease at 10-50 microM. The decrease in PAF by the 5LO inhibitor could not be circumvented by addition of 1 microM 5HETE, 5HPETE and LTB4, and may be attributed to the capacity of zileuton to increase the quantity of C20:4 in A23187-treated neutrophils. The inhibitory effect of C20:4 (20-40 microM) on PAF production could be antagonized by the protein kinase C inhibitor staurosporine (30 nM), but not by inhibitors of protein kinase A, tyrosine kinase or calmodulin kinase II. Taken together, these data demonstrate that C20:4 is selectively released from membrane phospholipids of A23187-stimulated neutrophils, and this C20:4 may play an important role in regulating the mobilization of C20:4 by altering PLA2 activity.

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Triflamp, a snake venom metalloproteinase, reduces neutrophil-platelet adhesion through proteolysis of PSGL-1 but not glycoprotein Ibα

Thrombosis and Haemostasis ◽

10.1160/th-03-09-0586 ◽

2004 ◽

Vol 91 (06) ◽

pp. 1177-1185 ◽

Cited By ~ 10

Author(s):

Yu-Lun Tseng ◽

Chia-Jung Lee ◽

Chun-Chieh Hsu ◽

Tur-Fu Huang

Keyword(s):

Platelet Adhesion ◽

Direct Interaction ◽

Critical Factor ◽

Inhibitory Effect ◽

Cathepsin G ◽

Time Dependent ◽

Dependent Manner ◽

Trimeresurus Flavoviridis ◽

Snake Venom Metalloproteinase ◽

Adhesive Effect

SummaryTriflamp, a metalloproteinase isolated from Trimeresurus flavoviridis, inhibits heterotypic adhesion between platelets and neutrophils. Coincubation studies demonstrate that direct interaction of triflamp with neutrophils is sufficient to inhibit the formation of neutrophil-platelet complexes. Its anti-adhesive effect is in a concentrationand incubation time-dependent manner. Triflamp reduces the expression of P-selectin glycoprotein ligand-1 (PSGL-1) on neutrophils and glycoprotein (GP) Ibα on platelets as probed by flow cytometry and Western blot. Moreover, triflamp disrupts P-selectin-mediated adhesion by cleaving PSGL-1 from the neutrophil surface.There are obvious differences regarding PSGL-1 proteolysis by triflamp and cathepsin G. Besides the NH2-terminus of PSGL-1, other sites are truncated by triflamp. The inhibitory effect of triflamp on PSGL-1 expression was prevented by pretreatment with a metalloproteinase inhibitor, phenanthroline. However, triflamptreated platelets fully keep the ability for binding to PAFor fMLP-stimulated neutrophils. Our results indicate that degradation of platelet GPIbα by triflamp does not interfere with neutrophil-platelet adhesion. Its effect on neutrophil PSGL-1 appears to be a critical factor for its inhibition on neutrophilplatelet interaction.

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Release of Type II phospholipase A2 immunoreactivity and phospholipase A2 enzymatic activity from human placenta

Journal of Endocrinology ◽

10.1677/joe.0.1530151 ◽

1997 ◽

Vol 153 (1) ◽

pp. 151-157 ◽

Cited By ~ 10

Author(s):

W Farrugia ◽

G E Rice ◽

M H Wong ◽

K F Scott ◽

S P Brennecke

Keyword(s):

Enzyme Activity ◽

Enzymatic Activity ◽

Phospholipase A2 ◽

Incubation Medium ◽

Placental Tissue ◽

Dependent Manner ◽

Type Ii ◽

Intracellular Enzyme ◽

Human Placental Tissue

Abstract The aim of this study was to determine whether Type II phospholipase A2 (PLA2) is released from late pregnant human placental tissue. Placental explants were incubated in vitro and the release of immunoreactive (ir) Type II PLA2 and PLA2 enzymatic activity into the medium was determined. Both irType II PLA2 and PLA2 enzymatic activity accumulated in the incubation medium in a time-dependent manner (P<0·0001). This release was not associated with a loss of cell membrane integrity, as indicated by measurement of the intracellular enzyme, lactate dehydrogenase, in the incubation medium. The concentration of irType II PLA2 and PLA2 enzyme activity present in incubation medium were significantly correlated (P<0·01). Consistent with the hypothesis that Type II PLA2 may be stored in secretory granules within human placental tissue, incubation in the presence of a membrane depolarising concentration of KCl (60 mm) caused the release of irType II PLA2 2·0-fold (P<0·001). PLA2 enzyme activity released into the incubation medium displays biochemical characteristics consistent with those previously reported for secretory PLA2 isozymes, that is, a requirement for millimolar concentrations of calcium for optimal enzyme activity, inhibited by reducing agents, such as dithiothreitol and insensitive to heat inactivation. The data obtained in this study establish that irType II PLA2 is released from term placenta, when incubated in vitro. The release of this extracellularly-active PLA2 isozyme may contribute to gestational and labour-associated increases in glycerophospholipid metabolism and prostaglandin formation. Journal of Endocrinology (1997) 153, 151–157

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Mechanism of Inhibitory Action on Platelet Activation of a Phospholipase A2 Isolated from Lachesis muta (Bushmaster) Snake Venom

Thrombosis and Haemostasis ◽

10.1055/s-0038-1665414 ◽

1997 ◽

Vol 78 (05) ◽

pp. 1372-1380 ◽

Cited By ~ 56

Author(s):

André L Fuly ◽

Olga L T Machado ◽

Elias W Alves ◽

Célia R Carlinis

Keyword(s):

Platelet Aggregation ◽

Enzymatic Activity ◽

Phospholipase A2 ◽

Inhibitory Activity ◽

Thermal Inactivation ◽

Anticoagulant Activity ◽

Gel Filtration ◽

Apparent Molecular Weight ◽

Crude Venom ◽

Lachesis Muta

SummaryCrude venom from Lachesis muta exhibited procoagulant, proteolytic and phospholipase A2 activities. A phospholipase A2, denoted LM-PLA2 was purified from L. muta venom to homogeneity, through a combination of chromatographic steps involving gel-filtration on Sephacryl S-200 HR and reverse phase chromatography on a C2/C18 column. LM-PLA2 presented a single polypeptide chain with an isoelectric point at pH 4.7 and apparent molecular weight of 17 kDa. Partial aminoacid sequence indicated a high degree of homology for LM-PLA2 with other PLA2 from different sources.LM-PLA2 displayed a potent enzymatic activity as measured by indirect hemolysis of red blood cells but it was neither lethal when injected i.p. into mice nor did it present anticoagulant activity. Furthermore, LM-PLA2 displayed a moderate inhibitory activity on the aggregation of rabbit platelets induced by low levels of ADP, thrombin and arachidonate. In contrast, platelet aggregation induced by high doses of collagen was strongly inhibited by LM-PLA2 as well as ATP-release. Treatment of the protein with p-bromophenacyl bromide or 2-mercapto-ethanol, as well as thermal inactivation studies, suggested that the platelet inhibitory effect of LM-PLA2 is dependent on its enzymatic activity. Thus, the platelet inhibitory activity of LM-PLA2 was shown to be dependent on the hydrolysis of plasma phospholipids and/or lipoproteins, most probably those rich in phosphatidylcholine. Surprisingly, lyso-phosphatidylcholine released by LM-PLA2 from plasma was shown to preferentially inhibited collagen-induced platelet aggregation, in contrast to other PLA2s, whose plasma hydrolytic products indistinctly affect platelet’s response to several agonists.

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