title: Biochemical characterization of a factor X activator protein purified from Walterinnesia aegyptia venom.
abstract: Factor X of blood coagulation cascade can be activated by both intrinsic and extrinsic activating complex, trypsin and some kind of snake venom. A factor X activator protein is reported in Elapidae snake venom. The aim of this study was to evaluate biochemical properties of factor X activator protein because of its prospective application in biochemical research and therapeutics. Crude venom was fractionated on a HPLC system Gold 126/1667 using a combination of Protein PAK 125 and Protein PAK 60 Columns. Molecular weight was determined using SDS-PAGE. Walterinnesia aegyptia venom was fractionated into several protein peaks, but procoagulant and factor X activation activity coexisted into peak no.6. It appeared as single band on native PAGE and molecular weight was 60,000 ± 3. Purified up to 37-fold over crude venom. It shortened recalcification time, effect was dose-dependent and strictly Ca(2++)-dependent. Factor X activator seems to be able to activate factor X specifically because it showed no activation activity on human prothrombin, plasminogen, or protein C. It did not hydrolyze factor Xa substrate S-2222, thrombin substrate S-2238, plasmin substrate S-2251 or S-2302 and kalikrein substrate S-2266. It did not hydrolyze synthetic ester benzoyl arginine ethyl ester. Procoagulant activity was completely inhibited by irreversible serine protease inhibitors phenylmethylsulphonyl fluoride and N-p-tosylphenylalanine chloromethyl ketone. This study illustrates that factor X activator from W. aegyptia is though different in many aspects from factor X activators of Viperidae and Crotalidae venoms, but shows several properties identical to factor X activators from Elapidae venoms.
authors.affiliation: aGomal Centre of Biochemistry & Biotechnology, Gomal, University, Dera Ismail Khan, Pakistan bDepartment of Clinical Laboratory Sciences, College of Applied, Medical Sciences, King Saud University, Riyadh, Saudi, Arabia.
authors.forename: Sami U
authors.initials: SU
authors.lastname: Khan
authors.forename: Saad S
authors.initials: SS
authors.lastname: Al-Saleh
mesh_terms: D000818:Animals; D001777:Blood Coagulation; D005170:Factor X / Q000235:genetics*; D006801:Humans; D008297:Male; D051379:Mice; D012910:Snake Venoms / Q000737:chemistry*
chemical_list: D012910:Snake Venoms; D005170:Factor X