Activates to at least 45 units per mg protein. One Unit hydrolyzes one micromole of benzoyl-L-tyrosine ethyl ester per minute at 25°C, pH 7.8 in the presence of calcium. An activity of 45 units per mg using the above definition, is the equivalent of 10,000 optical density of 1330 N.F. units per mg using ATEE as a substrate (1 BTEE unit = 29.5 USP/NF units).
Chymotrypsinogen A Assay
Store at 4°C.
Chymotrypsinogen activation: Dissolve 100 mg enzyme in 5 ml reagent grade water. Adjust pH to 3.0 with 1 N H2SO4. Add 2.5 ml of 0.5 M phosphate buffer pH 7.6 and readjust pH to 7.6 if necessary. Add 1 ml (1 mg) trypsin and dilute to a final volume of 10 ml with reagent grade water.
The zymogen form of chymotrypsin. Chymotrypsin preferentially catalyzes the hydrolysis of peptide bonds involving L-isomers of tyrosine, phenylalanine and tryptophan.