title: TA-2, a thrombin-like enzyme from the Chinese white-lipped green pitviper (Trimeresurus albolabris):  isolation, biochemical and biological characterization.
abstract: Through three chromatographic steps, a new thrombin-like enzyme (TLE), named TA-2, from the venom of the Chinese white-lipped green pitviper (Trimeresurus albolabris) has been isolated and purified to homogeneity. TA-2 was a single-chain glycoprotein with about 6% sugar, pI 3.9 and a molecular weight of 38.8 kD. Its N-terminal sequence (VVGGDECNIN) showed high sequence conformity with many other TLEs. In vitro, it coagulated bovine fibrinogen (108.6 NIH units/mg) and cleaved the Aα and Bβ chains of bovine fibrinogen-releasing fibrinopeptide A and B, but did not degrade bovine fibrin; displayed high stability at different temperature, pH, and presence of several divalent cations and inhibitors; also exhibited strong activity towards casein (192.3 units/mg) and high esterase activity upon Nα-p-tosyl-L-arginine methyl ester (11 units/mg); and behaved as a promoter to platelet aggregation induced by ADP or collagen. In vivo, TA-2 caused dose-dependent prolongation of bleeding time in mice, but had no hemorrhagic and edema-inducing activities even at high concentrations.
authors.affiliation: Animal Toxin Group, Chongqing Key Laboratory of Animal Biology, Chongqing Engineering Research Center of Bioactive Substance, Engineering Research Center of Active Substance and Biotechnology, Ministry of Education, College of Life Science bLibrary, Chongqing Normal University, Chongqing, China.
authors.forename: Qiyi
authors.initials: Q
authors.lastname: He
authors.forename: Heng
authors.initials: H
authors.lastname: Li
authors.forename: Bin
authors.initials: B
authors.lastname: Zhou
authors.forename: Haoping
authors.initials: H
authors.lastname: Wen
authors.forename: Jingbo
authors.initials: J
authors.lastname: Li
authors.forename: Bin
authors.initials: B
authors.lastname: Xiao
authors.forename: Kang
authors.initials: K
authors.lastname: Zhang
authors.forename: Wayne C
authors.initials: WC
authors.lastname: Hodgson
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Yu
mesh_terms: D000244:Adenosine Diphosphate / Q000737:chemistry; D000818:Animals; D002413:Cations, Divalent / Q000737:chemistry; D002417:Cattle; D002681:China; D003094:Collagen / Q000737:chemistry; D003435:Crotalid Venoms / Q000737:chemistry*; D004795:Enzyme Stability; D005340:Fibrinogen / Q000737:chemistry; D005344:Fibrinopeptide A / Q000378:metabolism; D005345:Fibrinopeptide B / Q000378:metabolism; D006023:Glycoproteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D010974:Platelet Aggregation / Q000187:drug effects; D059748:Proteolysis; D013379:Substrate Specificity; D013917:Thrombin / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D014106:Tosylarginine Methyl Ester / Q000378:metabolism; D017841:Trimeresurus / Q000502:physiology*
chemical_list: D002413:Cations, Divalent; D003435:Crotalid Venoms; D006023:Glycoproteins; D005344:Fibrinopeptide A; D005345:Fibrinopeptide B; D000244:Adenosine Diphosphate; D005340:Fibrinogen; D003094:Collagen; D014106:Tosylarginine Methyl Ester; D013917:Thrombin