CUPROENZYMES

Amine oxidases

Monoamine oxidase: inactivates catecholamines; serotonin, noradrenaline, tyramine, dopamine; inhibited by tricyclic antidepressant drugs.

Diamine oxidase: inactivates histamine (immune and allergic responses), and polyamines (cell proliferation).

Lysyl oxidase: deaminates lys in newly formed elastin and collagen, allowing cross-links to form. Thus involved in production of connective tissue, bone formation, mineralisation. Most abundant during growth.

Ferroxidases

Ceruloplasmin: a glycoprotein with 6 atoms of Cu per molecule. Four are involved in the catalytic site (oxidation/reduction). Catalyses oxidation of Fe²⁺, and helps to transfer stored Fe to sites of haemoglobin synthesis. Ceruloplasmin

Cytochrome C oxidase

This enzyme is present in mitochondria and catalyses the final (and rate-limiting) step in the electron transport chain, reducing O₂ → water and producing ATP.

Superoxide dismutase (SOD)

Important defence against oxidative damage, removing superoxide by converting it to hydrogen peroxide

Extracellular SOD: found especially in lungs, thyroid and uterus.

Cu/Zn SOD: present in most cells of body. (High levels associated with Down’s syndrome. -Why?)

Tyrosinase

Catalyses: Tyr → dopamine → dopaquinone → melanin.
Deficiency causes albinism.