Two acidic, anticoagulant PLA2 isoenzymes purified from the venom of monocled cobra Naja kaouthia exhibit different potency to inhibit thrombin and factor Xa via phospholipids independent, non-enzymatic mechanism.

<h4>Background</h4>The monocled cobra (Naja kaouthia) is responsible for snakebite fatality in Indian subcontinent and in south-western China. Phospholipase A2 (PLA2; EC 3.1.1.4) is one of the toxic components of snake venom. The present study explores the mechanism and rationale(s) for...

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Autores principales:	Ashis K Mukherjee, Bhargab Kalita, Rupamoni Thakur
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2014
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/0cbd1b1307b345c4b46d145117c26145
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spelling	oai:doaj.org-article:0cbd1b1307b345c4b46d145117c261452021-11-25T06:05:00ZTwo acidic, anticoagulant PLA2 isoenzymes purified from the venom of monocled cobra Naja kaouthia exhibit different potency to inhibit thrombin and factor Xa via phospholipids independent, non-enzymatic mechanism.1932-620310.1371/journal.pone.0101334https://doaj.org/article/0cbd1b1307b345c4b46d145117c261452014-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/25118676/?tool=EBIhttps://doaj.org/toc/1932-6203<h4>Background</h4>The monocled cobra (Naja kaouthia) is responsible for snakebite fatality in Indian subcontinent and in south-western China. Phospholipase A2 (PLA2; EC 3.1.1.4) is one of the toxic components of snake venom. The present study explores the mechanism and rationale(s) for the differences in anticoagulant potency of two acidic PLA2 isoenzymes, Nk-PLA2α (13463.91 Da) and Nk-PLA2β (13282.38 Da) purified from the venom of N. kaouthia.<h4>Principal findings</h4>By LC-MS/MS analysis, these PLA2s showed highest similarity (23.5% sequence coverage) with PLA2 III isolated from monocled cobra venom. The catalytic activity of Nk-PLA2β exceeds that of Nk-PLA2α. Heparin differentially regulated the catalytic and anticoagulant activities of these Nk-PLA2 isoenzymes. The anticoagulant potency of Nk-PLA2α was comparable to commercial anticoagulants warfarin, and heparin/antithrombin-III albeit Nk-PLA2β demonstrated highest anticoagulant activity. The anticoagulant action of these PLA2s was partially contributed by a small but specific hydrolysis of plasma phospholipids. The strong anticoagulant effect of Nk-PLA2α and Nk-PLA2β was achieved via preferential, non-enzymatic inhibition of FXa (Ki = 43 nM) and thrombin (Ki = 8.3 nM), respectively. Kinetics study suggests that the Nk-PLA2 isoenzymes inhibit their "pharmacological target(s)" by uncompetitive mechanism without the requirement of phospholipids/Ca(2+). The anticoagulant potency of Nk-PLA2β which is higher than that of Nk-PLA2α is corroborated by its superior catalytic activity, its higher capacity for binding to phosphatidylcholine, and its greater strength of thrombin inhibition. These PLA2 isoenzymes thus have evolved to affect haemostasis by different mechanisms. The Nk-PLA2β partially inhibited the thrombin-induced aggregation of mammalian platelets suggesting its therapeutic application in the prevention of unwanted clot formation.<h4>Conclusion/significance</h4>In order to develop peptide-based superior anticoagulant therapeutics, future application of Nk-PLA2α and Nk-PLA2β for the treatment and/or prevention of cardiovascular disorders are proposed.Ashis K MukherjeeBhargab KalitaRupamoni ThakurPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 9, Iss 8, p e101334 (2014)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Ashis K Mukherjee Bhargab Kalita Rupamoni Thakur Two acidic, anticoagulant PLA2 isoenzymes purified from the venom of monocled cobra Naja kaouthia exhibit different potency to inhibit thrombin and factor Xa via phospholipids independent, non-enzymatic mechanism.
description	<h4>Background</h4>The monocled cobra (Naja kaouthia) is responsible for snakebite fatality in Indian subcontinent and in south-western China. Phospholipase A2 (PLA2; EC 3.1.1.4) is one of the toxic components of snake venom. The present study explores the mechanism and rationale(s) for the differences in anticoagulant potency of two acidic PLA2 isoenzymes, Nk-PLA2α (13463.91 Da) and Nk-PLA2β (13282.38 Da) purified from the venom of N. kaouthia.<h4>Principal findings</h4>By LC-MS/MS analysis, these PLA2s showed highest similarity (23.5% sequence coverage) with PLA2 III isolated from monocled cobra venom. The catalytic activity of Nk-PLA2β exceeds that of Nk-PLA2α. Heparin differentially regulated the catalytic and anticoagulant activities of these Nk-PLA2 isoenzymes. The anticoagulant potency of Nk-PLA2α was comparable to commercial anticoagulants warfarin, and heparin/antithrombin-III albeit Nk-PLA2β demonstrated highest anticoagulant activity. The anticoagulant action of these PLA2s was partially contributed by a small but specific hydrolysis of plasma phospholipids. The strong anticoagulant effect of Nk-PLA2α and Nk-PLA2β was achieved via preferential, non-enzymatic inhibition of FXa (Ki = 43 nM) and thrombin (Ki = 8.3 nM), respectively. Kinetics study suggests that the Nk-PLA2 isoenzymes inhibit their "pharmacological target(s)" by uncompetitive mechanism without the requirement of phospholipids/Ca(2+). The anticoagulant potency of Nk-PLA2β which is higher than that of Nk-PLA2α is corroborated by its superior catalytic activity, its higher capacity for binding to phosphatidylcholine, and its greater strength of thrombin inhibition. These PLA2 isoenzymes thus have evolved to affect haemostasis by different mechanisms. The Nk-PLA2β partially inhibited the thrombin-induced aggregation of mammalian platelets suggesting its therapeutic application in the prevention of unwanted clot formation.<h4>Conclusion/significance</h4>In order to develop peptide-based superior anticoagulant therapeutics, future application of Nk-PLA2α and Nk-PLA2β for the treatment and/or prevention of cardiovascular disorders are proposed.
format	article
author	Ashis K Mukherjee Bhargab Kalita Rupamoni Thakur
author_facet	Ashis K Mukherjee Bhargab Kalita Rupamoni Thakur
author_sort	Ashis K Mukherjee
title	Two acidic, anticoagulant PLA2 isoenzymes purified from the venom of monocled cobra Naja kaouthia exhibit different potency to inhibit thrombin and factor Xa via phospholipids independent, non-enzymatic mechanism.
title_short	Two acidic, anticoagulant PLA2 isoenzymes purified from the venom of monocled cobra Naja kaouthia exhibit different potency to inhibit thrombin and factor Xa via phospholipids independent, non-enzymatic mechanism.
title_full	Two acidic, anticoagulant PLA2 isoenzymes purified from the venom of monocled cobra Naja kaouthia exhibit different potency to inhibit thrombin and factor Xa via phospholipids independent, non-enzymatic mechanism.
title_fullStr	Two acidic, anticoagulant PLA2 isoenzymes purified from the venom of monocled cobra Naja kaouthia exhibit different potency to inhibit thrombin and factor Xa via phospholipids independent, non-enzymatic mechanism.
title_full_unstemmed	Two acidic, anticoagulant PLA2 isoenzymes purified from the venom of monocled cobra Naja kaouthia exhibit different potency to inhibit thrombin and factor Xa via phospholipids independent, non-enzymatic mechanism.
title_sort	two acidic, anticoagulant pla2 isoenzymes purified from the venom of monocled cobra naja kaouthia exhibit different potency to inhibit thrombin and factor xa via phospholipids independent, non-enzymatic mechanism.
publisher	Public Library of Science (PLoS)
publishDate	2014
url	https://doaj.org/article/0cbd1b1307b345c4b46d145117c26145
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Two acidic, anticoagulant PLA2 isoenzymes purified from the venom of monocled cobra Naja kaouthia exhibit different potency to inhibit thrombin and factor Xa via phospholipids independent, non-enzymatic mechanism.

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