Research on the Diversity of PLA(2) Gene from Agkistrodon halys Pallas.

We used degenerate primers to amplify phospholipase A(2)(PLA(2)) gene by RT-PCR from venom total RNA of Agkistrodon halys Pallas, and screened with B-PLA(2) gene as probe. Finally we isolated three cDNAs containing A-PLA(2) and two other genes showing similar characteristic structure--Asn(49)-PLA(2) and BA-PLA(2). Their complete sequence was determined by bidirectional sequencing and their amino acid sequence was deduced. The amino acid sequence of A-PLA(2) deduced from the cDNA agreed with that determined by protein sequencing except for four residues; Asn(49 )-PLA(2) and B-PLA(2) are very alike (up to 95%), but the Asp(49)-PLA(2) of B-PLA(2) involved in the enzyme reaction is replaced by Asn(49) of Asn(49)-PLA(2). Therefore, it possibly affects the enzyme reaction of Asn(49)-PLA(2). The N-terminus sequence of BA-PLA(2) is highly homologous to B-PLA(2), but its C-terminus sequence is almost the same as A-PLA(2). The successful cloning of these isoenzyme genes not only discloses the structure diversity of PLA(2)(namely DNA modification and recombination), but also provides excellent material for the study of structure-function relationship in PLA(2).