Diazoacetyl Subtilisin

Subtilisin reacts at pH 6.8-7.8 with p-nitrophenyl diazoacetate to release p-nitrophenol and form diazoacetyl subtilisin. Although at pH 7.8 this derivative rapidly undergoes hydrolytic cleavage to regenerate active enzyme, the derivative can be trapped by rapidly lowering the pH to 5. Similarly, with ¹⁴C-labeled p-nitrophenyl diazoacetate, the corresponding radiochemically labeled diazoacetyl enzyme can be prepared. Photolysis of this radioactive derivative incorporates radioactivity into the protein, and subsquent hydrolysis gives rise to several radioactive components, which, however, have not yet been identified.