Bakır Metabolizması
Synopsis
Copper (Cu) is an essential trace element with an atomic number of 29 and an atomic weight of 63.54 that exists in +1 and +2 oxidation states in the organism, participating in redox reactions and serving as a cofactor for enzymes such as cytochrome oxidase, superoxide dismutase, tyrosinase, and lysyl oxidase. Its absorption depends on dietary content and occurs mainly in the small intestine (duodenum) via the CTR1 protein and metalloreductases that convert Cu²⁺ to Cu⁺; ascorbic acid and L-amino acids enhance absorption, whereas phytate, zinc, and molybdenum decrease it. In enterocytes, intracellular transport is mediated by chaperones including Atox1, Cox17, and CCS, as well as ATP7A and ATP7B transporter ATPases. Copper transported to the liver via albumin and transcuprein circulates predominantly (90%) bound to ceruloplasmin possessing ferroxidase activity, and its main route of excretion is through bile. Biochemically, copper plays critical roles in collagen and hemoglobin synthesis, iron metabolism, and melanin and myelin formation, with a daily requirement of 2-3 mg in adults where severe deficiency causes anemia, neutropenia, and osteoporosis. Among copper metabolic disorders, Menkes disease is an X-linked recessive intestinal absorption defect caused by ATP7A gene mutations, whereas autosomal recessive Wilson disease results from ATP7B gene mutations on chromosome 13, leading to impaired binding of copper to ceruloplasmin and copper accumulation in the liver, brain lenticular nucleus, and cornea (Kayser-Fleischer ring).
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