Molecular cloning of serine proteinases from Bothrops jararaca venom gland

Snake venom is known to contain an abundance of enzyme isoforms, and various disorders associated with envenomation have been ascribed partially to their diversified functions. Crude venom of Bothrops jararaca was subjected to conventional two-dimensional SDS-PAGE, followed by immunoblot analysis using an antiserum raised against KN-BJ 2, a serine proteinase previously isolated from this venom. A number of immunoreactive proteins with comparable molecular masses and different pIs emerged, implying the venom contains yet-unknown serine proteinases. A B. jararaca venom gland cDNA library was subsequently screened with a labeled KN-BJ 2 cDNA as a probe. Among a number of positive cDNA clones, three--HS112, HS114, and HS120--were selected and sequenced. These clones each had an open reading frame of 759-774 bp, and their deduced amino acid sequences illustrated considerable similarities to that of KN-BJ 2 as well as to those of serine proteinases of different origins. However, no apparent match to any of the deposited sequences was found in the current GenBank/EMBL databases, indicating that each of these cDNA clones encodes a serine proteinase distinct from the known enzymes. Analyses of the nucleotide and amino acid sequences of these cDNA clones support the accelerated evolution hypothesis proposed for snake venom enzymes.