Copper Flashcards
Copper and iron reduced and oxidized forms
Cu+1, Fe+2 = reduced
Cu+2, Fe+3 = oxidized
Cu absorption rate
50-80%
enhancers of Cu absorption
some aa
low pH
glutathione
acids
inhibitors of cu absorption
high pH
phytic acid
zinc
7 steps of Cu absorption
- Cu+2 released from food
- reduce to Cu+1 by reductase
- Cu+1 cross BBM by high-affinity Ctr1 transporter and DMT1
- in cytosol, copper binds to ‘chaperone’ for transport to target enzymes. Atox1 transports Cu+1 to trans-golgi network (TGN) which ATP7A relocates to BLM where it functions to export Cu from enterocyte
- copper delivered to enzymes by chaperones to use in some cells or bind to METALLOTHIONEIN for storage
- ATP7A transports Cu+1 across BLM
- copper attaches proteins for transport in blood. after hepatic uptake of copper, most copper is found in blood as ceruloplasmin
Cu transport
Ceruloplasmin leaves liver with Cu and delivers 60-70% of the Cu to tissues
**Unlike Fe and Zn, Cu excretion is regulated to maintain Cu homeostasis (balance)
Major route: excess Cu secreted into bile (exocytosis of vesicles containing Cu)
iron oxidation
ceruloplasmin:
Cu+2 converts Fe+2->Fe+3 for import/use in cells = ceruloplasmin-Cu+1 at end
(also functions to transport Cu in plasma to deliver to tissues)
hephaestin:
Cu+2 does this at enterocyte-Fe transport
low Cu cause microcytic anemia bc can’t utilize iron stores or from enterocyte
