Table 3.

Copper-dependent enzymes in mammals

Enzyme	Function
Cytochrome-c oxidase	Electron transport in mitochondria
Cu/Zn-SOD	Free radical detoxification
Metallothionein	Storage of excess Cu and other divalent metal ions [not Fe(II)]. Possible donor of Cu to certain apoproteins
Ceruloplasmin (extracellular)	Ferroxidase, promotes flow of Fe from liver to blood Scavenger of ROS, acute-phase reactant. Cu transport
Protein-lysine-6-oxidase	Cross-linking of collagen and elastin
Tyrosinase (catechol oxidase)	Formation of melanin
Dopamine-β-monooxygenase	Catecholamines production
α-Amidating enzyme	Modifies C-terminal ends of hypothalamic peptide hormones ending in glycine, leaving the COOH of the next to
	last AA amidated (necessary for hormone maturation)
Diamine oxidase	Inactivation of histamine and polyamines? (cellular and extracellular)
Amine oxidase (extracellular)	Inactivation of histamine, tyramine, dopamine, serotonin?
Peptidylglycine monooxygenase	Bioactivation of peptide hormones
Hephaestin	Ferroxidase, in trans-golgi of enterocytes; aids iron absorption homology to ceruloplasmin
CMGP	Ferroxidase/amine oxidase, homologous to ceruloplasmin (chondrocytes and eye ciliary epithelia)
β-Amyloid precursor protein	Normal function currently unknown
Prion protein (PrPC)	Copper binding properties suggests that it may protect against ROS; has SOD-like activity; may return copper to
	neurons at synapses (many cells)
S-Adenosylhomocysteine	Sulfur amino acid metabolism hydrolase
Angiogenin	Induction of blood vessel formation
Blood clotting factors V and VIII	Blood clotting