Factor V activation and inactivation by venom proteases

• Published in: Haemostasis Vol. 31; no. 3-6; p. 241
• Main Authors: Rosing, J, Govers-Riemslag, J W, Yukelson, L, Tans, G
• Format: Journal Article
• Language: English
• Published: Switzerland 01.05.2001
• Subjects: Animals; Endopeptidases - chemistry; Endopeptidases - pharmacology; Factor V - drug effects; Factor V - metabolism; Factor Va - drug effects; Factor Va - metabolism; Humans; Snake Venoms - chemistry; Snake Venoms - enzymology; Snake Venoms - pharmacology; Venoms - chemistry; Venoms - pharmacology
• ISSN: 0301-0147
• DOI: 10.1159/000048069

Blood coagulation factor V is a single-chain glycoprotein with M(r) = 330,000 which plays an important role in the procoagulant and anticoagulant pathways. Thrombin activates factor V into factor Va, a two-chain molecule which is composed of a heavy (M(r) = 105,000) and a light chain (M(r) = 71,000/74,000). Factor Va accelerates factor Xa-catalysed prothrombin activation more than 1,000-fold and under physiological conditions the cofactor activity of factor Va in prothrombin activation is down-regulated by activated protein C. Factor V can also be activated by a wide variety of snake venoms (e.g. from Vipera species, Naja naja oxiana, Bothrops atrox) and by proteases present in the bristles of a South American caterpillar (Lonomia achelous). Some venoms, notably of Vipera lebetina turanica and Lonomia achelous, contain proteases that are able to inactivate factor V or factor Va. Venom factor V activators are excellent tools in studying the structure-function relationship of factor V(a) and they are also used in diagnostic tests for quantification of plasma factor V levels and for the screening of defects in the protein C pathway. In this review, the structural and functional properties of animal venom factor V activators and inactivators is described.