title: A unique group of inactive serine protease homologues from snake venom.
abstract: A number of inactive serine protease homologues (SPHs), which have poorly understood functions, have been identified in invertebrates and vertebrates. Recently, several SPH transcripts have been reported from snake venom glands, which provide potential new tools for the study of the functions of SPHs. Herein we report for the first time a snake venom serine protease homologue (svSPH) protein, designated as TjsvSPH, isolated from the venom of Trimeresurus jerdonii. Despite its high sequence similarity to snake venom serine proteases (SVSPs), TjsvSPH is devoid of arginine esterase and proteolytic activity. This is probably due to the replacement of Arg-43 by His-43 in the catalytic triad. TjsvSPH did not influence the coagulation time of human plasma, induce human platelet aggregation, inhibit adenosine diphosphate/thrombin-induced human platelet aggregation or increase capillary permeability. Phylogenetic analysis showed that svSPHs were separated from SVSPs and formed an independent group. Structural analysis revealed that the structures of svSPHs are quite different from those of SPHs previously reported. These results indicate that snake venoms contain a unique group of svSPH proteins.
authors.affiliation: Department of Animal Toxinology, Kunming Institute of Zoology, The Chinese Academy of Sciences, 32 Jiaochang East Road, Kunming 650223, PR China.
authors.forename: Jianbo
authors.initials: J
authors.lastname: Wu
authors.forename: Yang
authors.initials: Y
authors.lastname: Jin
authors.forename: Shurong
authors.initials: S
authors.lastname: Zhong
authors.forename: Runqiang
authors.initials: R
authors.lastname: Chen
authors.forename: Shaowen
authors.initials: S
authors.lastname: Zhu
authors.forename: Wanyu
authors.initials: W
authors.lastname: Wang
authors.forename: Qiumin
authors.initials: Q
authors.lastname: Lu
authors.forename: Yuliang
authors.initials: Y
authors.lastname: Xiong
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001777:Blood Coagulation / Q000187:drug effects; D002199:Capillary Permeability / Q000187:drug effects; D005591:Chemical Fractionation; D003435:Crotalid Venoms / Q000737:chemistry* / Q000201:enzymology* / Q000494:pharmacology; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D010974:Platelet Aggregation / Q000187:drug effects; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D012697:Serine Endopeptidases / Q000737:chemistry* / Q000378:metabolism* / Q000494:pharmacology; D017841:Trimeresurus / Q000502:physiology*
chemical_list: D003435:Crotalid Venoms; D012697:Serine Endopeptidases