title: Medium molecular weight factor X activating enzyme from Vipera berus berus venom.
abstract: Vipera berus berus venom contains several factor X activating enzymes. One of them (VBFXAE) was separated by gel-filtration on Sephadex G-100 superfine and on a bacitracin-agarose column. The enzyme is a single-chain glycoprotein with mol. wt 38,000. The enzyme has several molecular forms with pI 3.5-4.5. After neuraminidase treatment the enzyme has pI 4.5. VBFXAE contains 2 Ca per mole. The activator is inactive on synthetic substrates, on casein, prothrombin, and fibrinogen, and appears to act specifically on factor X. The activator also weakly hydrolyses the insulin B-chain at the positions Ala14-Leu15 and Tyr16-Leu17. The cleavage of the insulin B-chain is inhibited by EDTA, suggesting the metalloproteinase nature of the enzyme.
authors.affiliation: Institute of Chemical Physics and Biophysics, Estonian Academy of Sciences, Tallinn.
authors.forename: M
authors.initials: M
authors.lastname: Samel
authors.forename: J
authors.initials: J
authors.lastname: Siigur
mesh_terms: D000596:Amino Acids / Q000032:analysis; D001777:Blood Coagulation / Q000187:drug effects; D002118:Calcium / Q000494:pharmacology; D005170:Factor X / Q000378:metabolism*; D006801:Humans; D007328:Insulin / Q000378:metabolism; D007526:Isoelectric Point; D008666:Metalloendopeptidases / Q000302:isolation & purification* / Q000494:pharmacology; D008970:Molecular Weight; D014757:Viper Venoms / Q000032:analysis*
chemical_list: D000596:Amino Acids; D007328:Insulin; D014757:Viper Venoms; D005170:Factor X; D008666:Metalloendopeptidases; D002118:Calcium