Properties of the Arginine Esterases fromBitis nasicornis(Horned Adder) Venom

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Abstract
Five forms of arginine esterase (DE-2 to DE-6) were purified from Bitis nasicornis venom by gel filtration on Sephadex G-50, followed by ion exchange chromatography on CM-cellulose and DEAE-sepharose. They contain 17.6-23.1% of carbohydrate, 242-244 amino acids including 14 half-cystine residues and have molecular masses of .apprx. 38 kDa [kilodaltons]. The enzymes have a high esterolytic activity towards N.alpha.-benzoyl-L-arginine ethyl ester but show no proteolytic activity against Azocoll and no clotting activity against fibrinogen. Their sequences of the first 19 amino-terminal residues are the same, but their carbohydrate content shows some variation. Furthermore, sequence studies on the N-terminal regions of the arginine esterases from B. nasicornis venom indicate that they share a significant degree of sequence homology with the kallikrein-like enzymes of Crotalus adamanteus and C. atrox venoms and also with porcine pancreatic kallikrein [EC 3.4.21.35]. Studies on tryptic glycopeptides of the arginine esterases show that carbohydrate occurs at the N-terminal region of the molecule and also towards the center.