title: Effects of temperature, pH, and inhibitors on the procoagulant characterization of FIa, a factor X activator from the venom of Daboia russellii siamensis (Myanmar).
abstract: FIa, a factor X activator, was isolated from the venom of Daboia russellii siamensis (Myanmar) after a series of chromatographic separations. FIa displayed procoagulant activity by shortening plasma recalcification time and converted human factor X (FX) to activated human factor X (FXa) by cleaving the heavy FX chain, possibly at the Arg51-Ile52 peptide. FIa was positive in a glycoprotein staining test, demonstrating that it is a glycoprotein. Optimal temperature and pH values were important for FIa procoagulant activity. Procoagulant activity was maintained above 85% of the initial activity at pH 7.0 approximately 8.0, and showed equally maximum activity at temperatures ranging from 30 to 50 degrees C. In addition, FIa procoagulant activity was completely inhibited by EDTA (5 mM), but not by PMSF (10 mM), suggesting that it is a metalloproteinase.
authors.affiliation: Department of Pharmacology, Sun Yat-sen University, Guangzhou, China.
authors.forename: Huanhuan
authors.initials: H
authors.lastname: Sun
authors.forename: Haiqing
authors.initials: H
authors.lastname: Ma
authors.forename: Guangyao
authors.initials: G
authors.lastname: He
authors.forename: Jiashu
authors.initials: J
authors.lastname: Chen
authors.forename: Pengxin
authors.initials: P
authors.lastname: Qiu
authors.forename: Guangmei
authors.initials: G
authors.lastname: Yan
mesh_terms: D000818:Animals; D019774:Blood Coagulation Factor Inhibitors / Q000494:pharmacology*; D004492:Edetic Acid / Q000494:pharmacology; D005170:Factor X / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008666:Metalloendopeptidases / Q000037:antagonists & inhibitors / Q000302:isolation & purification* / Q000494:pharmacology*; D002052:Myanmar; D011480:Protease Inhibitors / Q000494:pharmacology; D011506:Proteins / Q000037:antagonists & inhibitors / Q000302:isolation & purification* / Q000494:pharmacology*; D017840:Daboia; D013696:Temperature; D014757:Viper Venoms / Q000037:antagonists & inhibitors / Q000302:isolation & purification* / Q000494:pharmacology*
chemical_list: D019774:Blood Coagulation Factor Inhibitors; D011480:Protease Inhibitors; D011506:Proteins; D014757:Viper Venoms; C094035:daboiatoxin; D005170:Factor X; D004492:Edetic Acid; D008666:Metalloendopeptidases; C476775:factor X activator, Russell's viper