Hemorrhagic protease from the venom of Calloselasma rhodostoma.

1. A hemorrhagic protease I (HP-I) was isolated from Calloselasma rhodostoma venom by Sephadex G-75, DEAE-Sephacel and Q-Sepharose column chromatographies. 2. Homogeneity was established by the formation of a single band in acrylamide gel electrophoresis. 3. HP-I has a molecular weight of 34,800 and possesses hemorrhagic and proteolytic activities. Both activities are inhibited by ethylenediaminetetraacetic acid (EDTA), 1,10-phenanthroline, ethyleneglycolbis-(beta-aminoethyl ether) N,N'-tetraacetic acid (EGTA), and tetraethylenepentamine (TEP). However neither soybean trypsin inhibitor nor p-chlorobenzoic acid (PCMB) were found to have any effect. 4. The toxin contains 311 amino acid residues and exhibits an isoelectric point of 4.5. 5. The A alpha chain of fibrinogen was cleaved first, followed later by the B beta chain.