Studies on pancreatic proteinase

IN the foregoing paper [Farber and Wynne, 1935] methods were described for the study of the activity of pancreatic proteinase.These methods have been used in a study of the effects on the activity of the enzyme of chemical substances of various types, including carbohydrates, glycerol, amino-acids, triglycerides, bile and bile salts, indicators and dyes, salts of heavy metals and other salts.As substrate Kahlbaum's " casein (Hammarsten) " was used throughout, the concentration in the digestion mixtures being 0x80 % in the glycerol experiments and 0-90 % in all others.The digests were buffered at PH 8-7 with M/5 phosphate- borax buffer; solutions of the various compounds were, whenever necessary and practicable, adjusted to PH 8*7.The exceptions were those salts which formed precipitates at this alkalinity.The relative rates of hydrolysis listed in the tables which follow have been calculated from initial rates which, in turn, were based on determinations spaced, usually, at intervals of 20 sec.The total period of digestion, as a rule, was not more than 60 sec.; changes in pH during such short time intervals were negligible.Accurate estimations of initial velocity of hydrolysis were readily made with the aid of the procedures described in the previous paper.EXPERIMENTAL RESULTS.