A thrombin-like enzyme from bushmaster (Lachesis muta stenophyrs) venom

The clotting enzyme (Stenoxobin), from the venom of Lachesis muta stenophyrs, was purified by gel chromatography on Bio-gel P-100 followed by agmatine CH-Sepharose-4B and FPLC on Mono Q column. By SDS polyacrylamide gel electrophoresis the mol. wt was found to be 37,000. The enzyme is a glycoprotein with 1.6 moles of sialic acid per mole of protein and has an average content of 7.0% of neutral carbohydrates. The clotting and esterolytic (BAEE) activities were 843 NIH units/mg and 60.1 +/- 1.2 OD225 ml/min/mg, respectively, and could not be inhibited by heparin or hirudin. Amino acid analysis revealed a low content of tryptophan and a high content of acid residues. Stenoxobin acts upon human fibrinogen by releasing consecutively fibrinopeptides A and B from the alpha- and beta-chains of fibrinogen.