<prompt> Copper is a constituent of the enzymeLysyl oxidaseGlucose oxidaseXanthine oxidaseTransketolase  <response>: Role in Enzyme Action: Cu forms integral pa of ceain enzymes, e.g. some of cytochromes, cytochrome oxidase, tyrosinase, Monoamine oxidase MAO, Lysyl oxidase, Catalase, Ascorbic acid oxidase, uricase and superoxide dismutase. These enzymes contain about 550 mg of Cu per gram of enzyme proteinRef: MN Chatterjea Textbook of Medical Biochemistry, 6th edition, page no: 622 