Group IIA PLA Research Articles

Simultaneous inhibition of anti‐coagulation and inflammation: crystal structure of phospholipase A2 complexed with indomethacin at 1.4 Å resolution reveals the presence of the new common ligand‐binding site

A novel ligand-binding site with functional implications has been identified in phospholipase A(2) (PLA(2)). The binding of non-steroidal anti-inflammatory agent indomethacin at this site blocks both catalytic and anti-coagulant actions of PLA(2). A group IIA PLA(2) has been isolated from Daboia russelli pulchella (Russell's viper) which is enzymatically active as well as induces a strong anti-coagulant action. The binding studies have shown that indomethacin reduces the effects of both anti-coagulant and pro-inflammatory actions of PLA(2). A group IIA PLA(2) was co-crystallized with indomethacin and the structure of the complex has been determined at 1.4 A resolution. The structure determination has revealed the presence of an indomethacin molecule in the structure of PLA(2) at a site which is distinct from the conventional substrate-binding site. One of the carboxylic group oxygen atoms of indomethacin interacts with Asp 49 and His 48 through the catalytically important water molecule OW 18 while the second carboxylic oxygen atom forms an ionic interaction with the side chain of Lys 69. It is well known that the residues, His 48 and Asp 49 are essential for catalysis while Lys 69 is a part of the anti-coagulant loop (residues, 54-77). Indomethacin binds in such a manner that it blocks the access to both, it works as a dual inhibitor for catalytic and anti-coagulant actions of PLA(2). This new binding site in PLA(2) has been observed for the first time and indomethacin is the first compound that has been shown to bind at this novel site resulting in the prevention of anti-coagulation and inflammation.

Koninginins, phospholipase A 2 inhibitors from endophytic fungus Trichoderma koningii

Many isolated compounds from endophytic fungus have been useful to human beings, mainly those with medicinal applications and particularly those that can be used in inflammatory processes. Trichoderma fungi produce substances known as koninginins that have great structural similarity to compounds like flavonoids and vitamin E, which are able to inhibit the phospholipase A 2 (PLA 2). In this work, koninginins A, E and F (KonA, KonE and KonF, respectivamente) isolated from Trichoderma koningii had their capabilities of inhibiting edema-inducing, myotoxic and enzymatic activities of the total venom of Bothrops jararacussu (jararacuçu) snake analyzed, as well as one of its homolog forms of phospholipases A 2 (bjPLA 2—group IIB) and human secreted PLA 2 protein fusion (hsPLA 2—group IIA). KonA was not efficient in inhibiting the three activities analyzed in all the tests performed. Nevertheless, KonE and KonF present great capability in inhibiting the effects provoked not only by the venom but also by both PLA 2. The activities inhibition shown by KonE and KonF over the enzymes is significantly higher than those obtained over the total venom. KonE and KonF were slightly more efficient in the inhibition of the group IIB (bjPLA 2) PLA 2 effects than in the inhibition of the group IIA (hsPLA 2) PLA 2 effects. KonE and KonF structures are similar to vitamin E and, possibly, the action mode of these molecules is similar to the one produced by the vitamin. These results, apparently, indicate that koninginins E and F, as well as vitamin E, present structural regions that might be used as start points in seeking for new and specific anti-inflammatory drugs against such enzymes.

Phospholipase A 2 in acute pancreatitis: review

Phospholipase A 2 (PLA 2) is a key enzyme in the generation of prostanoids that are important mediators of inflammation. Review of recent literature on the involvement of PLA 2 in acute pancreatitis (AP). Pancreatic group IB PLA 2 mediates local pancreatic cell injury but not distant organ damage. Nonpancreatic group (G) IIA PLA 2 is an acute-phase protein that functions in defense against infection and removal of injured cells but is quite harmless to uninjured cells. The concentration of GIIA PLA 2 in serum correlates with the severity of AP. PLA 2 inhibitors are effective in the therapy of experimental AP but have not penetrated to clinical use as drugs to treat the human disease. Specific immunoassays have been developed for the measurement of both GIB PLA 2 and GIIA PLA 2 in serum. The former assay is a method suitable for detecting pancreatic injury and the latter to assess the severity of AP.

Psoriasis treated with ursodeoxycholic acid: three case reports

We report three Japanese patients with psoriasis vulgaris associated with nonalcoholic fatty liver disease in which the skin lesions dramatically resolved after treatment of the fatty liver disease with ursodeoxycholic acid (UDCA). According to the literature, arachidonic acid is released from phospholipid by phospholipase A(2) (PLA(2)) and is a precursor of eicosanoids, including prostaglandins, leucotrienes, and thromboxanes, which are potent inflammatory mediators. PLA(2) activity has been reported to be significantly raised in the serum and skin tissue of patients with psoriasis. UDCA has been reported to suppress the increased activity of group IIA PLA(2), a secretory low-molecular-weight PLA(2) (PLA(2)IIA), in HepG2 cells (a human hepatoblastoma-derived cell line) and in gallbladder and gallbladder bile samples from patients with cholesterol stones. Thus, UCDA may improve the skin lesions of patients with psoriasis by suppressing PLA(2)IIA activity.

Structural and Functional Effects of Tryptophans Inserted into the Membrane-binding and Substrate-binding Sites of Human Group IIA Phospholipase A2

Phospholipase A(2) (PLA(2)) enzymes become activated by binding to biological membranes and hydrolyze phospholipids to free fatty acids and lyso-phospholipids, the precursors of inflammatory mediators. To understand the functional significance of amino acid residues at key positions, we have studied the effects of the substitution of Val(3) (membrane binding surface) and Phe(5) (substrate binding pocket) of human group IIA PLA(2) by tryptophan on the structure and function of the enzyme. Despite the close proximity of the sites of mutations, the V3W mutation results in substantial enhancement of the enzyme activity, whereas the F5W mutant demonstrates significantly suppressed activity. A structural analysis of all three proteins free in buffer and bound to membranes indicates that large differences in activities result from distinct conformational changes in PLA(2)s upon membrane binding. Although PLA(2) and the V3W mutant demonstrate a decrease in helical content and an increase in helix flexibility, the F5W mutant experiences partial distortion of the alpha-helical structure presumably resulting from the tendency of Trp(5) to insert into the membrane. Furthermore, whereas the PLA(2) and the V3W mutant bind to the membrane at similar and apparently productive-mode orientation, the F5W mutant binds to membranes with a distinctly different orientation. It is suggested that both the stimulatory effect of the V3W mutation and the inhibitory effect of the F5W mutation result from the high affinity of Trp for the membrane-water interface. Although Trp(3) at the membrane binding face of PLA(2) facilitates the proper membrane binding of the enzyme, Trp(5) in the internal substrate binding site causes partial unwinding of the N-terminal helix in order to interact with the membrane.

Purification, characterization and cytokine release function of a novel Arg-49 phospholipase A 2 from the venom of Protobothrops mucrosquamatus

Group IIA phospholipase A 2 (PLA 2) are major components in Viperidae/Crotalidae venom. In the present study, a novel PLA 2 named promutoxin with Arg at the site 49 has been purified from the venom of Protobothrops mucrosquamatus by chromatography. It consists of 122 amino acid residues with a molecular mass of 13,656 Da assessed by MALDI-TOF. It has the structural features of snake venom group IIA PLA 2s, but has no PLA 2 enzymatic activity. Promutoxin shows higher amino acid sequence identity to the K49 PLA 2s (72–95%) than to D49 PLA 2s (52–58%). Promutoxin exhibits potent myotoxicity in the animal model with as little as 1 μg of promutoxin causing myonecrosis and myoedema in the gastrocnemius muscle of mice. Promutoxin is also able to stimulate the release of IL-12, TNFα, IL-6 and IL-1β from human monocytes, and induce IL-2, TNFα and IL-6 release from T cells, indicating that this snake venom group IIA PLA 2 is actively involved in the inflammatory process in man caused by snake venom poisoning.

Crystal structures of the complexes of a group IIA phospholipase A2 with two natural anti‐inflammatory agents, anisic acid, and atropine reveal a similar mode of binding

Secretory low molecular weight phospholipase A(2)s (PLA(2)s) are believed to be involved in the release of arachidonic acid, a precursor for the biosynthesis of pro-inflammatory eicosanoids. Therefore, the specific inhibitors of these enzymes may act as potent anti-inflammatory agents. Similarly, the compounds with known anti-inflammatory properties should act as specific inhibitors. Two plant compounds, (a) anisic acid (4-methoxy benzoic acid) and (b) atropine (8-methyl-8-azabicyclo oct-3-hydroxy-2-phenylpropanoate), have been used in various inflammatory disorders. Both compounds (a) and (b) have been found to inhibit PLA(2) activity having binding constants of 4.5 x 10(-5) M and 2.1 x 10(-8) M, respectively. A group IIA PLA(2) was isolated and purified from the venom of Daboia russelli pulchella (DRP) and its complexes were made with anisic acid and atropine. The crystal structures of the two complexes (i) and (ii) of PLA(2) with compounds (a) and (b) have been determined at 1.3 and 1.2 A resolutions, respectively. The high-quality observed electron densities for the two compounds allowed the accurate determinations of their atomic positions. The structures revealed that these compounds bound to the enzyme at the substrate - binding cleft and their positions were stabilized by networks of hydrogen bonds and hydrophobic interactions. The most characteristic interactions involving Asp 49 and His 48 were clearly observed in both complexes, although the residues that formed hydrophobic interactions with these compounds were not identical because their positions did not exactly superimpose in the large substrate-binding hydrophobic channel. Owing to a relatively small size, the structure of anisic acid did not alter upon binding to PLA(2), while that of atropine changed significantly when compared with its native crystal structure. The conformation of the protein also did not show notable changes upon the bindings of these ligands. The mode of binding of anisic acid to the present group II PLA(2) is almost identical to its binding with bovine pancreatic PLA(2) of group I. On the other hand, the binding of atropine to PLA(2) is similar to that of another plant alkaloid aristolochic acid.

Antimicrobial activity of myotoxic phospholipases A 2 from crotalid snake venoms and synthetic peptide variants derived from their C-terminal region

A short peptide derived from the C-terminal region of Bothrops asper myotoxin II, a Lys49 phospholipase A 2 (PLA 2), was previously found to reproduce the bactericidal activity of its parent molecule. In this study, a panel of eight PLA 2 myotoxins purified from crotalid snake venoms, including both Lys49 and Asp49-type isoforms, were all found to express bactericidal activity, indicating that this may be a common action of the group IIA PLA 2 protein family. A series of 10 synthetic peptide variants, based on the original C-terminal sequence 115–129 of myotoxin II and its triple Tyr→Trp substituted peptide p115-W3, were characterized. In vitro assays for bactericidal, cytolytic and anti-endotoxic activities of these peptides suggest a general correlation between the number of tryptophan substitutions introduced and microbicidal potency, both against Gram-negative ( Salmonella typhimurium) and Gram-positive ( Staphylococcus aureus) bacteria. Peptide variants with high bactericidal activity also tended to be more cytolytic towards skeletal muscle C2C12 myoblasts, thus limiting their potential in vivo use. However, the peptide variant pEM-2 (KKWRWWLKALAKK) showed reduced toxicity towards muscle cells, while retaining high bactericidal potency. This peptide also showed the highest endotoxin-neutralizing activity in vitro, and was shown to functionally interact with lipopolysaccharide (LPS) using a chimeric bacteria model. The bactericidal and anti-endotoxic properties of pEM-2, combined with its relatively low toxicity towards eukaryotic cells, highlight it as a promising candidate for further evaluation of its antimicrobial potential in vivo.

Role of Charge Properties of Bacterial Envelope in Bactericidal Action of Human Group IIA Phospholipase A2against Staphylococcus aureus

Mammalian Group IIA phospholipases A(2) (PLA(2)) potently kill Staphylococcus aureus. Highly cationic properties of these PLA(2) are important for Ca(2+)-independent binding and cell wall penetration, prerequisites for Ca(2+)-dependent degradation of membrane phospholipids and bacterial killing. To further delineate charge properties of the bacterial envelope important in Group IIA PLA(2) action against S. aureus, we examined the effects of mutations that prevent specific modifications of cell wall (dltA) and cell membrane (mprF) polyanions. In comparison to the parent strain, isogenic dltA(-) bacteria are approximately 30-100x more sensitive to PLA(2), whereas mprF(-) bacteria are <3-fold more sensitive. Differences in PLA(2) sensitivity of intact bacteria reflect differences in cell wall, not cell membrane, properties since protoplasts from all three strains are equally sensitive to PLA(2). A diminished positive charge in PLA(2) reduces PLA(2) binding and antibacterial activity. In contrast, diminished cell wall negative charge by substitution of (lipo)teichoic acids with d-alanine reduces antibacterial activity of bound PLA(2), but not initial PLA(2) binding. Therefore, the potent antistaphylococcal activity of Group IIA PLA(2) depends on cationic properties of the enzyme that promote binding to the cell wall, and polyanionic properties of cell wall (lipo)teichoic acids that promote attack of membrane phospholipids by bound PLA(2).

Differential roles of ionic, aliphatic, and aromatic residues in membrane-protein interactions: a surface plasmon resonance study on phospholipases A2.

The roles of cationic, aliphatic, and aromatic residues in the membrane association and dissociation of five phospholipases A(2) (PLA(2)), including Asp-49 PLA(2) from the venom of Agkistrodon piscivorus piscivorus, acidic PLA(2) from the venom of Naja naja atra, human group IIa and V PLA(2)s, and the C2 domain of cytosolic PLA(2), were determined by surface plasmon resonance analysis. Cationic interfacial binding residues of A. p. piscivorus PLA(2) (Lys-10) and human group IIa PLA(2) (Arg-7, Lys-10, and Lys-16), which mediate electrostatic interactions with anionic membranes, primarily accelerate the membrane association. In contrast, an aliphatic side chain of the C2 domain of cytosolic PLA(2) (Val-97), which penetrates into the hydrophobic core of the membrane and forms hydrophobic interactions, mainly slows the dissociation of membrane-bound protein. Aromatic residues of human group V PLA(2) (Trp-31) and N. n. atra PLA(2) (Trp-61, Phe-64, and Tyr-110) contribute to both membrane association and dissociation steps, and the relative contribution to these processes depends on the chemical nature and the orientation of the side chains as well as their location on the interfacial binding surface. On the basis of these results, a general model is proposed for the interfacial binding of peripheral proteins, in which electrostatic interactions by ionic and aromatic residues initially bring the protein to the membrane surface and the subsequent membrane penetration and hydrophobic interactions by aliphatic and aromatic residues stabilize the membrane-protein complexes, thereby elongating the membrane residence time of protein.

Sera of patients suffering from inflammatory diseases contain group IIA but not group V phospholipase A 2

During recent years, the high phospholipase A 2 (PLA 2) concentrations at sites of inflammation and in circulation in several life-threatening diseases, such as sepsis, multi-organ dysfunction and acute respiratory distress syndrome, has generally been ascribed to the non-pancreatic group IIA PLA 2. Recently the family of secreted low molecular mass PLA 2 enzymes has rapidly expanded. In some cases, a newly described enzyme appeared to be cross-reactive with antibodies against the group IIA enzyme. For this reason, reports describing the expression of group IIA PLA 2 during inflammatory conditions need to be reevaluated. Here we describe the identification of the PLA 2 activity in sera of acute chest syndrome patients and in sera of trauma victims. In both cases, the PLA 2 activity was identified as group IIA. This classification was based upon cross-reactivity with monoclonal antibodies against group IIA PLA 2 which do not recognize the recombinant human group V enzyme. Moreover, purification of the enzymatic activity from the two sera followed by N-terminal amino acid sequence analyses revealed only the presence of group IIA enzyme.

The molecular basis of phosphatidylcholine preference of human group-V phospholipase A2

Human group-V phospholipase A(2) (hVPLA(2)) is a secretory phospholipase A(2) (PLA(2)) that is involved in eicosanoid formation in such inflammatory cells as macrophages and mast cells. We showed that hVPLA(2) can bind phosphatidylcholine membranes and hydrolyse phosphatidylcholine molecules much more efficiently than human group-IIa PLA(2), which accounts for its high activity on the outer plasma membrane of mammalian cells. To understand the molecular basis of the high phosphatidylcholine specificity of hVPLA(2), we mutated several residues (Gly-53, Glu-56 and Glu-57) that might be involved in interaction with an active-site-bound phospholipid molecule. Phospholipid head-group specificities of mutants determined using polymerized mixed-liposome substrates indicate that a small glycine residue in position 53 is important for accommodating a bulky choline head group. Also, results indicated that two anionic residues, Glu-56 and Glu-57, favourably interact with cationic head groups of phosphatidylcholine and phosphatidylethanolamine. Together, these steric and electrostatic properties of the active site of hVPLA(2) allow for effective binding and hydrolysis of a bulky cationic choline head group of phosphatidylcholine, which is unique among mammalian secretory PLA(2)s.

Low Molecular Weight Group IIA and Group V Phospholipase A2 Enzymes Have Different Intracellular Locations in Mouse Bone Marrow-derived Mast Cells

The subcellular location of the enzymes of eicosanoid biosynthesis is critical for their co-ordinate action in the generation of leukotrienes and prostaglandins. This activity is thought to occur predominantly at a perinuclear location. Whereas the subcellular locations of cytosolic phospholipase (PL) A(2) and each of the pathway enzymes of eicosanoid generation have been defined, the distribution of the low molecular weight species of PLA(2) has remained elusive because of the lack of antibodies that distinguish among homologous family members. We have prepared affinity-purified rabbit antipeptide IgG antibodies that distinguish mouse group IIA PLA(2) and group V PLA(2). Immunofluorescence staining and immunogold electron microscopy reveal different subcellular locations for the enzymes. Group IIA(2) PLA(2) is present in the secretory granules of mouse bone marrow-derived mast cells, consistent with its putative role in facilitating secretory granule exocytosis and its consequent extracellular action. In contrast, group V PLA(2) is associated with various membranous organelles including the Golgi apparatus, nuclear envelope, and plasma membrane. The perinuclear location of group V PLA(2) is consistent with a putative interaction with translocated cytosolic PLA(2) in supplying arachidonic acid for generation of eicosanoid products, while the location in Golgi cisternae may also reflect its action as a secreted enzyme. The spatial segregation of group IIA PLA(2) and group V PLA(2) implies that these enzymes are not functionally redundant.

Crucial role of group IIA phospholipase A(2) in oleic acid-induced acute lung injury in rabbits.

Group IIA secretory phospholipase A(2) (sPLA(2)) has been implicated in a variety of inflammatory diseases including acute lung injury (ALI); however, the role of sPLA(2) in this disorder remains unclear. The aim of the present investigation was to examine the role of this enzyme in a model of ALI induced by oleic acid (OA) in rabbits by testing human group IIA phospholipase A(2) (PLA(2)) inhibitor, S-5920/LY315920Na. Experimental groups consisted of a saline control group (n = 8), an OA control group (n = 10) infused intravenously with OA (0.1 ml/kg/h for 2 h), and three groups given OA + S-5920/LY315920Na (three different doses, n = 8, respectively). Infusion of OA provoked pulmonary hemorrhage and edema formation, protein leakage, and massive neutrophil infiltration, resulting in severe hypoxemia and impaired lung compliance. PLA(2) activity was detected in the bronchoalveolar lavage fluid (BALF), but not plasma, which correlated well with severity of lung injury in this model. Pretreatment with S-5920/LY315920Na diminished the OA-induced PLA(2) activity in the BALF and dose-dependently attenuated the previously described lung injury induced by OA, accompanied by protection against lung surfactant degradation and production of thromboxane A(2) (TXA(2)) and leukotriene B(4) (LTB(4)). S-5920/LY315920Na also inhibited the OA-induced production of interleukin-8 (IL-8), both in plasma and BALF. Thus, sPLA(2) appears to play a key role in OA-induced lung injury, suggesting that the group IIA PLA(2) inhibitor may be a promising agent for patients with acute respiratory distress syndrome (ARDS).

Secretory Group IIA Phospholipase A2 Generates Anti-apoptotic Survival Signals in Kidney Fibroblasts

Mammalian group IIA phospholipase A(2) (PLA(2)) is believed to play important roles in inflammation, cell injury, and tumor resistance. However, the cellular site of action has not been clearly defined as it has long been recognized that group IIA PLA(2) is both a secretory and mitochondrial protein. The purpose of this study was to determine the subcellular target of the group IIA PLA(2) and its role in apoptosis stimulated by growth factor withdrawal. Cloning of the rat liver group IIA PLA(2) demonstrated a typical secretory signal and no alternative splicing of the primary transcript. When a sequence including the signal peptide and first 8 residues in the mature enzyme or the entire PLA(2) (including the signal peptide) was fused to enhanced green fluorescent protein, the fusion protein was directed to the secretory pathway rather than mitochondria in baby hamster kidney (BHK) cells. To examine the role of group IIA PLA(2) in cell injury, wild type (wt) rat group IIA PLA(2) and a mutant group IIA PLA(2) containing a His-47 --> Gln mutation (at the catalytic center) were transfected into BHK cells and cells stably expressing these constructs were isolated. After deprivation of growth factors, both normal BHK cells and BHK cells expressing mutant PLA(2) underwent massive apoptosis, while BHK cells expressing wt PLA(2) showed considerable resistance to growth factor withdrawal-induced apoptosis. The secretory PLA(2) inhibitors 12-epi-scalaradial and aristolochic acid abrogated resistance to apoptosis in the wt PLA(2) expressing cells. These two inhibitors did not induce cell death in the presence of fetal bovine serum, suggesting that they induce cell death by blocking PLA(2) generated survival signals. This study demonstrates that group IIA PLA(2) generates anti-apoptotic survival signals in BHK cells targeting the secretory pathway, and suggests that high levels of group IIA PLA(2) accumulated at inflammatory sites may not only regulate inflammation, but also may protect cells from unnecessary death induced by pro-inflammatory agents.

Enzymatic properties of rat group IIA and V phospholipases A 2 compared

Group IIA and V phospholipases A 2 (PLA 2s) are known to play a role in inflammatory responses. We have constructed a bacterial expression vector for rat group IIA and V PLA 2s, over-expressed, folded and purified the proteins with the aim to study and compare the properties of the enzymes in detail. For zwitterionic phospholipid micelles, both enzymes display optimum activity at pH 8.0 and absolutely require Ca 2+ for enzymatic activity. In the presence of substrate, group V PLA 2 has a high affinity for Ca 2+ ( K Ca2+=90 μM) while K Ca2+ of group IIA PLA 2 was found to be 1.6 mM. The absence of substrate only marginally influences the Ca 2+ affinities. In contrast to group IIA PLA 2, group V PLA 2 does not show a jump in the activity profile at substrate concentrations around the critical micelle concentration. Direct binding studies using n-alkylphosphocholines indicate that group V PLA 2 forms protein-lipid aggregates at pre-micellar lipid concentrations in a cooperative and Ca 2+-dependent manner. This behavior, which is comparable to that observed for the PLA 2 from Naja melanoleuca snake venom, reflects the high affinity of this enzyme for zwitterionic phospholipids. Competitive inhibition by the substrate analogues ( R)-2-dodecanoylaminohexanol-1-phosphocholine and its phosphoglycol derivative was tested on zwitterionic micelles as substrate. Group IIA PLA 2 shows a preference for the phosphoglycol inhibitor whereas the phosphocholine inhibitor binds stronger to the active site of group V PLA 2. The enzymatic activity was also measured on zwitterionic liposomes which appear to be much better substrates for group V PLA 2 than for group IIA PLA 2. The overall results suggest that group V PLA 2 is better suited for action on biological membranes than group IIA PLA 2.

Expression and characterization of human group V phospholipase A 2

Group V phospholipase A 2 (GV-PLA 2) has been shown to be involved in signal transduction and inflammatory processes in cellular studies, but the physical and biochemical properties of this important enzyme have been unclear. We report the over-expression and characterization of GV-PLA 2. The GV-PLA 2 cDNA was synthesized from human heart polyA + mRNA by RT-PCR, and an expression construct containing the GV-PLA 2 was established. After expression in Escherichia coli cells, the protein was solubilized and purified to homogeneity in a single step using nickel affinity chromatography. The purified GV-PLA 2 protein was folded to form active enzyme. The recombinant GV-PLA 2 has an absolute requirement for Ca 2+ for enzymatic activity. The optimum pH for this enzyme is pH 8.5 in Tris-HCl buffer with sonicated vesicles as substrate. GV-PLA 2 preferentially hydrolyzes phosphatidylethanolamine (PE) vesicles compared to phosphatidylcholine (PC) vesicles. However, hydrolysis of PC and PE is equivalent in mixed vesicles of the phospholipids. The fatty acid preference of GV-PLA 2 is linoleoyl>palmitoyl>arachidonyl with a PC head group and sonicated vesicles. 3-(3-Actamide-1-benzyl-2-ethylindolyl-5-oxy)propane phosphonic acid (LY311727), a potent inhibitor of human group IIA PLA 2, strongly inhibits GV-PLA 2 with an IC 50 value of about 36 nM which is comparable to its inhibition of group IIA PLA 2.