title: Primary structure of a protein C activator from Agkistrodon contortrix contortrix venom.
abstract: The amino acid sequence of a protease, protein C activator, from Agkistrodon contortrix contortrix venom was determined. Peptide fragments obtained by chemical or enzymatic cleavage of the S-carboxymethylated protein were purified by gel filtration and reverse-phase high-performance liquid chromatography. The present study demonstrates that protein C activator from A. contortrix contortrix venom is a trypsin-type serine protease that is composed of 231 residues with a molecular weight of 25,095 for the polypeptide portion of the molecule. By analogy to the mammalian serine proteases, the catalytic triad in venom protein C activator consists of His-40, Asp-85, and Ser-177. The protein also contains three N-linked glycosylation sites at Asn-21, Asn-78, and Asn-129. The amino acid sequence of protein C activator exhibits a high degree of sequence identity with other snake venom proteases: 73% with batroxobin, 68% with flavoxobin, and 55% with Russell's viper venom factor V activator.
authors.affiliation: Department of Biochemistry, University of Washington, Seattle 98195.
authors.forename: B A
authors.initials: BA
authors.lastname: McMullen
authors.forename: K
authors.initials: K
authors.lastname: Fujikawa
authors.forename: W
authors.initials: W
authors.lastname: Kisiel
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D003435:Crotalid Venoms / Q000032:analysis*; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000302:isolation & purification*; D010446:Peptide Fragments / Q000032:analysis; D010447:Peptide Hydrolases; D011486:Protein C / Q000378:metabolism*; D012689:Sequence Homology, Nucleic Acid
chemical_list: C031442:Agkistrodon venoms; D003435:Crotalid Venoms; D009842:Oligopeptides; D010446:Peptide Fragments; D011486:Protein C; C047135:protein C activator peptide; D010447:Peptide Hydrolases