[Isolation and characteristics of alpha-specific thrombin-like enzymes from venoms of the common pit viper (Agkistrodon halys halys) and the eastern pit viper (the central Asian subspecies Agkistrodon halys blomhoffii)].

Ancistron-H and Ancistron-B--two novel thrombin-like serine proteinases--have been purified 188- and 194-fold with a 95% recovery from the venoms of two Middle Asian subspecies of the pit viper--Agkistrodon halys halys and Agkistrodon halys Blomhoffii, using one-step affinity chromatography on agarose with an immobilized dye--Cibacron Blue F3GA (Blue-Sepharose 6B CL). The purified enzymes are one-chain glycoproteins with molecular masses of 34 and 29 kDa, pI of 6.6 and 6.3 and specific activities of 410 and 110 NIH units/mg protein, respectively. Their major amino acids are Gly, Val, Ser and Asp for Ancistron-H and Glu, Gly, Ser and Asp for Ancistron-B. During incubation with fibrinogen the enzymes cleave only the fibrinopeptide A from the A alpha-chain, leaving the B beta- and gamma-chains intact. Both enzymes hydrolyse arginine esters and thrombin-specific chromogenic peptide substrates, and display a weak caseinolytic activity but no fibrinolytic activity.