He Q, Li H, Zhou B, Wen H, Li J, Xiao B, Zhang K, Hodgson WC, Yu X
TA-2, a thrombin-like enzyme from the Chinese white-lipped green pitviper (Trimeresurus albolabris): isolation, biochemical and biological characterization.
Blood coagulation & fibrinolysis : an international journal in haemostasis and thrombosis. 2012 Jul 01; 23: 445-53.
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"ŠkD. 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 AÎ± and BÎ² 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 NÎ±-p-tosyl-L-arginine methyl ester (11"Šunits/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.