Copper-reducing enzyme CYBRD1
I finally found the enzyme that reduces copper (2) to Cu 1+ outside of the cell - CYBD1.
Turns out, the enzyme uses intracellular ascorbate for the reaction.
The whole story around MitoSynergy supplement is built on the idea, that Cu2+ is useless and toxic, because the body can’t use it.
Well, this enzyme seems like the candidate to solve that.
From the comments to the post
Here is a interesting excerpt from my nutrition science book— EFFECT OF DIETARY REDUCING AGENTS ON COPPER ABSORPTION
Van Campen and Gross were the first to show that dietary ascorbic acid (vitamin C) attenuates the absorption of Cu from the gut of mammals. The mechanism is probably related to the chemical reduction of Cu from +2 to +1 oxidation state by the acid, which is a strong reducing agent.
© 2006 by Taylor & Francis Group, LLC
Sports Nutrition: Vitamins and Trace Elements
However, recent studies suggest that Cu +1 is the form favored by the specific Cu transporter, Ctr1, in the duodenal enterocyte. Van den Berg’s group did extensive work on the effects of ascorbic acid on Cu absorption and showed that the acid lowered the amount of soluble Cu in the small intestine of rats, which subsequently impaired Cu absorption.
Finley and Cerklewski found that young men fed 500 mg of ascorbic acid three times/day showed a gradual decrease in plasma Cu and Cp activity over 64 days of treatment.
When the ascorbic acid supplement was removed, both parameters rebounded within 20 days.
Milne et al. demonstrated a negative effect of dietary ascorbic acid on Cu status of non-human primates, but did not find an effect on Cu status when adult women were given 1500 mg of ascorbic acid and only 0.6 mg of Cu/day for 42 days.
Another study showed that feeding 1500 mg of ascorbic acid and 0.67 mg Cu/day to women for 135 days had no effect on Cu balance; however, Cp activity was lower.
Based on these studies, it seems likely that short-term consumption of high amounts of ascorbic acid will have little effect on Cu status if the consumption of Cu is normal; however, information is not available to state conclusively that long-term consumption of the vitamin would not have a negative effect on Cu absorption, especially if dietary Cu intakes were low.