Diazoacetyl subtilisin

Area of Science:

• Enzymology
• Protein Chemistry
• Biochemistry

Background:

• Subtilisin is a serine protease with a well-characterized active site.
• Diazo compounds are known to react with active site residues of proteases.
• Understanding enzyme modification and reactivity is crucial for protein engineering.

Purpose of the Study:

• To investigate the reaction of subtilisin with p-nitrophenyl diazoacetate.
• To characterize the resulting diazoacetyl subtilisin derivative.
• To explore methods for stabilizing the derivative and identify its photolysis products.

Main Methods:

• Enzymatic reaction of subtilisin with p-nitrophenyl diazoacetate at varying pH.
• Preparation of radiochemically labeled diazoacetyl subtilisin using (14)C-labeled reagent.
• Photolysis of the radioactive derivative.
• Hydrolysis of photolyzed products.

Main Results:

• Subtilisin reacts with p-nitrophenyl diazoacetate, forming diazoacetyl subtilisin and releasing p-nitrophenol.
• The diazoacetyl subtilisin derivative can be trapped and stabilized by rapid pH reduction to 5.
• Photolysis of the radiolabeled derivative leads to incorporation of radioactivity into the protein.
• Subsequent hydrolysis yields unidentified radioactive components.

Conclusions:

• Diazoacetyl subtilisin is a reactive intermediate that can be stabilized under specific conditions.
• Photolysis of this derivative suggests covalent modification of subtilisin, yielding novel, yet unidentified, labeled fragments.