[Trypsin and chymotrypsin inhibitors from viper venom]. / Ingibitory tripsina i khimotripsina iz iada gadiuki.

Inhibitors of trypsin and alpha-chymotrypsin with Mr of about 7000 Da and isoelectric points of greater than 10 and 9.9, respectively, were isolated from the venom of the common viper Vipera berus berus, using gel filtration and ion exchange chromatography. The inhibitor I prefers alpha-chymotrypsin (Ki = 4.6 X 10(-10) M) for the formation of an enzymeinhibitor complex at a molar ratio of 1:1. The inhibitor II prefers trypsin (Ki = 6.7 X 10(-11) M), forms an EI-complex at a molar ratio of 1:2, but also inhibits alpha-chymotrypsin (Ki = 1.4 X 10(-9) M) and hog pancreatic kallikrein (Ki = 1.6 X 10(-8) M). The inhibitor II contains no valine or methionine.

[Separation of a bradykinin-releasing enzyme from the proteolytic complex of Levantine viper venom]. / Vydelenie bradikininobrazuiushchego fermenta i proteoliticheskogo kompleksa iada giurzy.

Two serine hydrolases have been separated from the proteolytic complex of the venom of Levantine viper, Vipera lebetina turanica. The enzyme with mol. weight of 50,000 +/- 5,000, pH-optimum of 8.5 and isoelectric point in the range of 5.6--6.6 had proteolytic activity against casein and hydrolyzed benzoyl-arginine p-nitroanilide. The other enzyme with mol. weight of 37,000 +/- 2,000, pH optimum of 9 and isoelectric point in the range of 4.1--4.5 had no effect on benzoylarginine p-nitroanilide, casein or hemoglobin, but possessed a bradykinin-releasing activity. Both enzymes were stereoselective against L-arginine, hydrolyzing tosyl-L-arginine methyl ester without having any effect on D-arginine ester. The interaction of the enzymes with a number of N(alpha)-arylsulfonylarginine methyl esters has been studied. The influence of the substitute X in the arylsulfonyl part of the substrates upon their hydrolysis by the bradykinin-releasing enzyme has been described by the Hammett equation of rho omicron = 1.14 +/- 0.33 (r = 0.974).