[Determination of the enzymatic activity of trypsin and chymotrypsin using denatured 125I-labeled albumin].

The method of the determination of trypsin and chymotrypsin activity by means of modified 125I-labelled albumin is described. The radioalbumin, denatured with an alkaline solution of urea, is about 20 times more sensitive to enzymatic hydrolysis than native radioalbumin. Owing to the higher sensitivity of the proposed procedure, as compared with other available techniques, this method enables accurate determination of lower enzyme concentrations than it has been possible until now. The method is suitable for the measurement of the rate of the proteolysis of raw enzymatic extracts as well as for exact kinetic measurements of purified enzymes.