ACCELERATED EVOLUTION OF CROTALINAE SNAKE-VENOM GLAND SERINE PROTEASES

Eight cDNAs encoding serine proteases isolated from Trimeresuras flavo viridis (habu snake) and T. gramineus (green habu snake) venom gland c DNA libraries showed that nonsynonymous nucleotide substitutions have accumulated in the mature protein-coding regions to cause amino acid c hanges, Southern blot analysis of T. flavoviridis genomic DNAs using t wo proper probes indicated that venom gland serine protease genes form a multigene family in the genome. These observations suggest that ven om gland serine proteases have diversified their amino acid sequences in an accelerating manner. Since a similar feature has been pre,iously discovered in crotalinae snake venom gland phospholipase A(2) (PLA(2) ) isozyme genes, accelerated evolution appears to be universal in plur al isozyme families of crotalinae snake venom gland.