Site directed mutagenesis: a tool for enzyme mechanism dissection.

Protein engineering has become the principle means of examining the active site of an enzyme to identify and quantify the roles of specific residues in ligand binding, specificity and catalysis. Site-specific mutagenesis has extended our knowledge gained from X-ray crystallography, and has provided striking proof that the intricate active-site geometry is supported by the remainder of the protein infrastructure for maximum catalytic efficiency.