Comparison of amino terminal region of three isoenzymes of phospholipases A2 (TFV PL-Ia, TFV PL-Ib, TFV PL-X) from Trimeresurus flavoviridis (habu snake) venom and the complete amino acid sequence of the basic phospholipase, TFV PL-X.

Three phospholipases (PLA2s) isolated from Japanese habu snake (Trimeresurus flavoviridis) venom differ from each other in the physiological symptoms induced in animals. The amino acid compositions and amino terminal sequences of these isoenzymes have been compared. TFV PL-Ia and TFV PL-Ib resemble each other very closely, but TFV PL-X has a distinctly different amino acid composition and amino terminal region. The complete amino acid sequence of the basic PLA2, TFV PL-X, was determined by sequencing the four peptides obtained by the cleavage of Asp-Pro bonds. The overlapping peptide was obtained by cleaving tryptophanyl bond and the carboxy terminal region was determined by sequencing the chymotryptic peptide. TFV PL-X consisted of a single chain of 122 amino acid residues, including 14 half-cystine residues. It is a group II A PLA2 and is homologous with the phospholipase super family. However, it has a distinctly different sequence compared with the other PLA2s from the venom of Trimeresurus species.