[Effect of chemical modification on proteinase interaction with inhibitors, on their coagulability and acute toxicity]

A comparative study of terrylytin, trypsin and products of their covalent binding to human serum albumin was carried out. Modification caused a decrease of the affinity of both enzymes for proteinase inhibitors from the blood. The inhibition constant for terrylytin was increased 3-4-fold, that for trypsin - by 2 or 3 orders. The recalcification time of human blood plasma in the presence of terrylytin remained practically unchanged after enzyme chemical modification. Trypsin binding to albumin decreased its coagulability. Preparations of modified enzymes were characterized by a decreased acute toxicity, this effect being especially well-pronounced in the case of trypsin. The decrease of terrylytin toxicity due to modification can be accounted for by a decrease in its affinity for alpha2-macroglobulin. The decrease of trypsin toxicity is apparently due to a decrease of its coagulability due to binding to albumin.