The precise three-dimensional shape of an enzyme's active site is determined by its tertiary structure, which is maintained by hydrogen bonds, disulfide bridges, and ionic interactions between amino acid side-chains.

An enzyme will catalyze the hydrolysis of both the $L$- and $D$-enantiomers of a chiral dipeptide at identical rates because the covalent amide linkage being cleaved is planar and achiral.

A competitive inhibitor drug acts by binding to the active site of an enzyme, blocking the substrate from entering, and its design can be optimized using computer-aided molecular modeling.

Enzymes are highly stereospecific catalysts because they are constructed from chiral $L$-amino acids, resulting in an asymmetric active site.