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Common acylcarboxypeptidase A intermediates for ester substrates containing different cleaving alcohols
The Journal of Biological Chemistry
|June 5, 1986
Summary
Carboxypeptidase A uses a nucleophilic mechanism involving Glu-270, forming an acylenzyme intermediate. This intermediate
Area of Science:
- Biochemistry
- Enzymology
- Protein Catalysis
Background:
- Carboxypeptidase A is a key enzyme in protein and peptide metabolism.
- Understanding its catalytic mechanism is crucial for biochemistry and drug development.
Purpose of the Study:
- To elucidate the catalytic mechanism of carboxypeptidase A in ester hydrolysis.
- To provide direct evidence for the involvement of a nucleophilic pathway.
Main Methods:
- Studied the ester hydrolysis of trans-alpha-(benzoylamino)cinnamoyl derivatives.
- Analyzed the pH dependence of the catalytic constant (kcat).
Main Results:
- Identified an enzyme-substrate complex (ES') breakdown.
- Demonstrated that Glu-270 is involved in forming an anhydride acylcarboxypeptidase A.
- Observed similar kcat values for different alcohol portions, indicating common acylenzyme intermediates.
Conclusions:
- The study provides direct evidence for a nucleophilic mechanism in carboxypeptidase A action.
- The catalytic process is primarily driven by the acyl moiety, not the alcohol portion.