Products from the Photolysis of Diazoacetyl Chymotrypsin

From the ¹ From the James Bryant Conant Laboratory of the Chemistry Department of Harvard University, Cambridge, Massachusetts 02138

1. A new and convenient synthesis of p-nitrophenyl diazoacetate has been devised from p-nitrophenyl chloroformate and diazomethane.

2. p-Nitrophenyl diazoacetate reacts stoichiometrically with chymotrypsin to yield diazoacetyl chymotrypsin.

3. Photolysis of the diazoacetyl enzyme with light of wave length greater than 320 mµ yields a mixture of (a) glycolic acid and regenerated chymotrypsin and (b) modified protein which retains the carbon atoms of the diazoacetyl group.

4. Acid hydrolysis of the protein obtained from photolysis yields O-carboxymethylserine, identified by chromatographic and other comparisons with an authentic sample and with material formed on photolysis of azaserine.

5. In addition, small amounts of 1-carboxymethylhistidine and of O-carboxymethyltyrosine were obtained. The origin of the former is uncertain, but the latter may arise from photolysis of a dimer of the diazoacetylated enzyme.

6. Most of the products presumably arise from a carbene formed as a primary product of the photolysis of the diazoester.

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