In the synthesis of collagen which enzyme requires copper ?

Ceain lysyl residues are modified by lysyl oxidase, a copper-containing protein that conves e-amino groups to aldehydes. The aldehydes can either undergo an aldol condensation to form a C = C double bond or to form a Schiff base (eneimine) with the e-amino group of an unmodified lysyl residue, which is subsequently reduced to form a C - N single bond. Menkes syndrome, characterized by kinky hair and growth retardation, reflects a dietary deficiency of the copper required by lysyl oxidase, which catalyzes a key step in the formation of the covalent cross-links that strengthen collagen fibers. Ref: Harper's Illustrated Biochemistry, 30E (2015) pg no 47.