title: Isolation, expression and characterization of a novel dual serine protease inhibitor, OH-TCI, from king cobra venom.
abstract: Snake venom Kunitz/BPTI members are good tools for understanding of structure-functional relationship between serine proteases and their inhibitors. A novel dual Kunitz/BPTI serine proteinase inhibitor named OH-TCI (trypsin- and chymotrypsin-dual inhibitor from Ophiophagus hannah) was isolated from king cobra venom by three chromatographic steps of gel filtration, trypsin affinity and reverse phase HPLC. OH-TCI is composed of 58 amino acid residues with a molecular mass of 6339Da. Successful expression of OH-TCI was performed as the maltose-binding fusion protein in E. coli DH5alpha. Much different from Oh11-1, the purified native and recombinant OH-TCI both had strong inhibitory activities against trypsin and chymotrypsin although the sequence identity (74.1%) between them is very high. The inhibitor constants (K(i)) of recombinant OH-TCI were 3.91 x 10(-7) and 8.46 x10(-8)M for trypsin and chymotrypsin, respectively. To our knowledge, it was the first report of Kunitz/BPTI serine proteinase inhibitor from snake venom that had equivalent trypsin and chymotrypsin inhibitory activities.
authors.affiliation: Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan 650223, China.
authors.forename: Ying-Ying
authors.initials: YY
authors.lastname: He
authors.forename: Shu-Bai
authors.initials: SB
authors.lastname: Liu
authors.forename: Wen-Hui
authors.initials: WH
authors.lastname: Lee
authors.forename: Jin-Qiao
authors.initials: JQ
authors.lastname: Qian
authors.forename: Yun
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002918:Chymotrypsin / Q000378:metabolism; D004546:Elapid Venoms / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D017815:Elapidae; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D015842:Serine Proteinase Inhibitors / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D014357:Trypsin / Q000378:metabolism
chemical_list: D004546:Elapid Venoms; D015842:Serine Proteinase Inhibitors; C533254:trypsin- and chymotrypsin inhibitor, Ophiophagus hannah; D002918:Chymotrypsin; D014357:Trypsin