title: Beta-fibrinogenase from the venom of Vipera lebetina.
abstract: An arginine esterase was purified from the venom of Vipera lebetina by gel filtration on Sephadex G-100 and by affinity and DEAE-cellulose chromatography. The enzyme has a mol. wt of 52,500 and pI approximately 3. It is a glycoprotein containing 23% of neutral sugars, and has extremely high thermostability. The esterase activity is inhibited by diisopropylfluorophosphate (DFP) and phenylmethylsulfonyl fluoride (PMSF). The Km and kcat values are for alpha-N-benzoyl-L-arginine ethyl ester (BAEE) 7.7 x 10(-5) M and 43.8 sec-1, for p-tosyl-L-arginine methyl ester (TAME) 3.6 x 10(-4) M and 39.8 sec-1 (pH 8.5, 25 degrees C, and for alpha-N-benzoyl-DL-arginine-4-nitroanilide (BAPNA) 1.8 x 10(-4) M and 0.94 sec-1 (pH 8.3, 25 degrees C), respectively. Lysine esters are not hydrolyzed. The enzyme has weak caseinolytic activity and hydrolyzes glucagon at the sites Lys12-Tyr13, Arg17-Arg18 and Arg18-Ala19. In fibrinogen it cleaves B beta-chain first and later also the A alpha-chain.
authors.affiliation: Institute of Chemical Physics and Biophysics, Estonian Academy of Sciences, Tallinn, U.S.S.R.
authors.forename: E
authors.initials: E
authors.lastname: Siigur
authors.forename: A
authors.initials: A
authors.lastname: Mähar
authors.forename: J
authors.initials: J
authors.lastname: Siigur
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002241:Carbohydrates / Q000032:analysis; D002846:Chromatography, Affinity; D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D005340:Fibrinogen / Q000378:metabolism; D006868:Hydrolysis; D007525:Isoelectric Focusing; D008969:Molecular Sequence Data; D013379:Substrate Specificity; D013917:Thrombin / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D014757:Viper Venoms / Q000737:chemistry*
chemical_list: D000596:Amino Acids; D002241:Carbohydrates; D014757:Viper Venoms; D005340:Fibrinogen; D013917:Thrombin