Amino acid sequence of a thrombin like enzyme, elegaxobin II, from the venom of Trimeresurus elegans (Sakishima-Habu).

The amino acid sequence of a thrombin like enzyme , named elegaxobin II, isolated from the venom of Trimeresurus elegans (Sakishima-habu) was determined by Edman sequencing of the peptides which was derived from digests with cyanogen bromide, achromobacter protease I, trypsin, endoproteinase Asp-N, and chymotrypsin. Elegaxobin II consisted of 233 amino acids and showed conservation of the catalytic amino acid residues (His(57), Asp(102), and Ser(195)) of chymotrypsin family serine protease in its amino acid sequence. The carboxyterminal amino acid, Leu, was determined using carboxypeptidase Y. This enzyme contains glucosamine and an N-linked glycosylation site. Elegaxobin II was 91% homologous in sequence to elegaxobin and protease I from the same snake venom, and it was 67, 75, 31 and 26% homologous in sequences to flavoxobin, KN-BJ 2, human kallikrein and bovine thrombin, respectively. Elegaxobin II lacked thrombin's ETW (146-148) loop, as well as its functionally important YPPW (60-insertion loop).