Covalent modification of an enzyme is any alteration involving the formation or breaking of covalent bonds on the protein, and it constitutes a distinct mode of regulating catalytic activity beyond changes in substrate concentration or non-covalent binding. Three theoretically distinct cases illustrate the principle: small post-translational modifications (such as methylation, acetylation, and glycosylation) that alter a residue's charge, acid–base behavior, and electrostatic interactions and thereby the protein's overall properties; zymogens, inactive precursor enzymes that require a covalent modification — typically proteolytic cleavage by another enzyme — to become catalytically active, permitting activity to be restricted to a specific location; and suicide inhibitors, which form a covalent linkage to the enzyme and therefore rarely dissociate, producing effectively irreversible inhibition. This topic belongs to biochemistry and enzymology and connects protein structure–function theory to metabolic regulation and pharmacology.
Covalent modification of an enzyme is any alteration involving the formation or breaking of covalent bonds on the protein, and it constitutes a distinct mode of regulating catalytic activity beyond c…