Functionally Important Residues for the Anticoagulant Activity of A Basic Phospholipase A2 from the Agkistrodon Halys Pallas

2002 ◽  
Vol 9 (5) ◽  
pp. 427-434 ◽  
Author(s):  
Xiaoyan Zhong ◽  
Haomang Jiao ◽  
Liang Fan ◽  
Xiangfu Wu ◽  
Yuancong Zhou
Keyword(s):  
Phospholipase A2 ◽  
Anticoagulant Activity

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

1997 ◽  
Vol 78 (05) ◽  
pp. 1372-1380 ◽  
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.

Crystal structure of a novel phospholipase A2 from Naja naja sagittifera with a strong anticoagulant activity

Toxicon ◽  
2005 ◽  
Vol 46 (8) ◽  
pp. 865-875 ◽  
Author(s):  
Talat Jabeen ◽  
Nagendra Singh ◽  
Rajendra K. Singh ◽  
A.S. Ethayathulla ◽  
Sujata Sharma ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phospholipase A2 ◽  
Anticoagulant Activity ◽  
Naja Naja

scholarly journals Human Prothrombin/Phospholipids Interaction. Competitive Effect of an Anticoagulant Venom Phospholipase A2

1977 ◽  
Author(s):  
G.A. Boffa ◽  
R. Benarous ◽  
M.C. Boffa
Keyword(s):  
Protein Binding ◽  
Phospholipase A2 ◽  
Binding Site ◽  
Anticoagulant Activity ◽  
Anticoagulant Effect ◽  
Competitive Effect ◽  
Chemical Denaturation ◽  
Photo Oxidation ◽  
Partial Chemical ◽  
Anticoagulant Property

The high anticoagulant activity of the phospholipase A2 isolated from a Viperidae venom was explained by the formation of a complex with phospholipid at its protein binding site (1). The anticoagulant effect was reversible with specific antiphospholipase A2 immunoglobulins.The interaction between 125 I prothrombin and phospholipid in the presence of calcium was impaired by the phospholipase. A competitive effect between prothrombin and the phospholipase was demonstrated. It did not appear sufficient to explain the anticoagulant property of the enzyme. This effect was abolished after photo-oxidation of the phospholipase. In the presence of another Viperidae phospholipase A2, devoid of anticoagulant activity, no competitive effect was observed.The presence of several sites responsible for anticoagulant, catalytic and recognition properties have been looked for by various partial chemical denaturation processes.

scholarly journals Anticoagulant Activity of Naja nigricollis Venom Is Mediated by Phospholipase A2 Toxins and Inhibited by Varespladib

Toxins ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 302
Author(s):  
Taline D. Kazandjian ◽  
Arif Arrahman ◽  
Kristina B. M. Still ◽  
Govert W. Somsen ◽  
Freek J. Vonk ◽  
...  
Keyword(s):  
Phospholipase A2 ◽  
Anticoagulant Activity ◽  
West African ◽  
Snake Venoms ◽  
The West ◽  
Coagulation Assays ◽  
Venom Toxins ◽  
African Black ◽  
Snake Venom Metalloproteinase ◽  
Species Specific

Bites from elapid snakes typically result in neurotoxic symptoms in snakebite victims. Neurotoxins are, therefore, often the focus of research relating to understanding the pathogenesis of elapid bites. However, recent evidence suggests that some elapid snake venoms contain anticoagulant toxins which may help neurotoxic components spread more rapidly. This study examines the effects of venom from the West African black-necked spitting cobra (Naja nigricollis) on blood coagulation and identifies potential coagulopathic toxins. An integrated RPLC-MS methodology, coupled with nanofractionation, was first used to separate venom components, followed by MS, proteomics and coagulopathic bioassays. Coagulation assays were performed on both crude and nanofractionated N. nigricollis venom toxins as well as PLA2s and 3FTx purified from the venom. Assays were then repeated with the addition of either the phospholipase A2 inhibitor varespladib or the snake venom metalloproteinase inhibitor marimastat to assess whether either toxin inhibitor is capable of neutralizing coagulopathic venom activity. Subsequent proteomic analysis was performed on nanofractionated bioactive venom toxins using tryptic digestion followed by nanoLC-MS/MS measurements, which were then identified using Swiss-Prot and species-specific database searches. Varespladib, but not marimastat, was found to significantly reduce the anticoagulant activity of N. nigricollis venom and MS and proteomics analyses confirmed that the anticoagulant venom components mostly consisted of PLA2 proteins. We, therefore, conclude that PLA2s are the most likely candidates responsible for anticoagulant effects stimulated by N. nigricollis venom.

Phospholipase A2 and Competitive Inhibition of Procoagulant Phospholipids

1975 ◽  
Author(s):  
M. C. Boffa ◽  
G. A. Boffa
Keyword(s):  
Thin Layer ◽  
Phospholipase A2 ◽  
Gel Electrophoresis ◽  
Competitive Inhibition ◽  
Anticoagulant Activity ◽  
Polyacrylamide Gel Electrophoresis ◽  
Phospholipase Activity ◽  
Vipera Berus ◽  
Layer Chromatography ◽  
Gradient Chromatography

A protein with anticoagulant and phospholipase Aa activities was isolated by chromatography, from Vipera berus venom. The phospholipase activity was demonstrated on isolated platelet phospholipids and derivatives were analysed on thin layer chromatography. The strong anticoagulant activity on recalcified platelet poor plasma, is not dependent upon any proteolytic effect. It is due to a competitive inhibition of the phospholipid procoagulant activity. The inhibition constant has been determined.The same molecule appeared to be responsible for both activities as demonstrated by continuous gradient chromatography, polyacrylamide gel electrophoresis and electro-focusing.Inactivation studies permitted to consider that each of both activities was related to a different site on the same molecule.

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