Identification of Histidine 303 as the Catalytic Base of Lysyl Oxidase via Site-Directed Mutagenesis.

Lysyl oxidase (LOX) is a copper-dependent amine oxidase enzyme that catalyzes the formation of crosslinkages of collagen and elastin in connective tissues by oxidative deamination of lysine. Using site-directed mutagenesis, Histidine 303 has been shown to be a key residue that acts as the necessary catalytic base for this enzyme to function properly. Histidine 303 was mutated to isoleucine to remove catalytic activity and to aspartate and glutamate, respectively, in order to provide alternate residues that could act as a general base that could maintain catalytic activity.