A mutation that results in a single amino acid substitution in the active site of an enzyme

May alter the specificity for its substrate

Explanation:

The active site of an enzyme refers to the specific region of an enzyme that serves as the binding site for its one or more substrates. Binding of substrates to the active site of their enzymes is required for catalysis. Enzymes are highly specific for their substrates. Type of amino acids present in the active site of the enzymes and their interactions with substrates regulate the specificity of the enzyme. If a mutation substitutes the amino acid of the active site, it may increase or decrease the specificity of the enzyme for its substrate.

May alter the specificity for its substrate