Amino Acid Sequence of Trimeresurus flavoviridis Phospholipase A2

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Abstract
The amino acid sequence of phospholipase A2 from the venom of Trimeresurus flavoviridis (the Habu snake) was determined. The enzyme subunit has a molecular weight of 13,764 and coosists of a single polypeptide chain of 122 amino acids and seven disulfide bonds. The fragmentation was conducted by digesting the reduced and S-carboxymethylated derivative of the protein with Achromobacter protease I, chymotrypsin, and trypsin, respectively. Achromobacter protease I peptides were used for alignment and to establish overlaps over chymotryptic and tryptic peptides. The automated Edman degradation of the S-carboxymethylated protein, which was extended to the N-terminal 30 amino acid residues, supplemented the deletions found with the enzymatic peptides alone. T. flavoviridis phospholipase A2 was found to be highly (65*67%) homologous in sequence to the enzymes from T. okinavensis, Crotalus adamanteus, and Crotalus atrox (viperid family) and less (35–44%) homologous to those from clapid snakes and mammalian pancreas. The T. flavoviridis enzyme appears to be similar in secondary structure composition to the C. atrox enzyme.