A colorimetric method for the determination of chymotrypsin activity

The L isomers of esters, amides, and hydrazides of the general formula RCONHCHR1COR2 where R = CH3-, C6H5-, etc., R1 = C6H6CH2-, p-HO-C6H4CH2-, etc., and R2 = -OCH3, -NH2, or -NHNH2, are known to be hydrolyzed by chymotrypsin (l-6). It has now been found that the corresponding hydroxamides, RCONHCHR1CONHOH, where R1 = C6H5CH2-, are also hydrolyzed by this enzyme (Table I). Aside from the obvious usefulness of the above hydroxamides in the further definition of chymotrypsin activity we wish to point out that these latter substrates provide the basis for a simple, sensitive, and rapid calorimetric method for the determination of chymotrypsin activity which can be extended to a number of other proteolytic enzymes.