reaction needs fixing : GO:0008823 Cu+ + NAD+ + H+ = Cu2+ + NADH

[gocentral]

A metabolic modeller in my office has just pointed out that

GO:0008823 cupric reductase activity Cu+ + NAD+ + H+ = Cu2+ + NADH.

should be Cu+ + NAD+ = Cu2+ + NADH + H+

v

Reported by: ValWood

Original Ticket: geneontology/ontology-requests/11236

[gocentral]

The suggested reaction looks unbalanced but I don't know how to balance it and couldn't find any useful hints. Maybe someone at Rhea or ChEBI could sort this one out?

Original comment by: deustp01

[gocentral]

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 A metabolic modeller in my office has just pointed out that

 GO:0008823 cupric reductase activity

• assigned_to: Jane Lomax

Original comment by: tberardini

[gocentral]

Jane, I'm assigning this to you and hoping that you can walk down the hall to talk to the Rhea/ChEBI folks for advice.

Thanks,

Tanya

Original comment by: tberardini

[gocentral]

Duygu Dikicioglu who reported this to me said it was correct in Rhea. I tried to check this but I could not find this enzyme entry searching on term name or EC number.... val

Original comment by: ValWood

[gocentral]

A Google search on cupric reductase turns up this GO term and some papers describing entities with combined cupric and ferric reductase activities, e.g., PMID: 18498772. That paper provides a plausible-seeming description of what the enzyme is used for and some evidence for the double activity, but it doesn't lead to an EC number. However, a search on ferric reductase leads to http://en.wikipedia.org/wiki/Ferric-chelate_reductase, which points to EC 1.16.1.7, which even (unlike the Wikipedia entry) associates a balanced reaction with the activity: 2 Fe(II)-siderophore + NAD+ + H+ = 2 Fe(III)-siderophore + NADH (http://www.chem.qmul.ac.uk/iubmb/enzyme/EC1/16/1/7.html).

Not an answer, but perhaps a good starting point? But neither this EC entry nor any of its 1.16.1.~ siblings admits to any activity on copper ions, only iron. Don't know if that's a lethal problem.

Original comment by: deustp01

[gocentral]

I asked Duygu to clarify, does that help?

Hi Val,

I am confused because the reactions involving NAD/NADH balance usually are the other way around. A common explanation is as follows: When a pair of H atoms (2 protons + 2 electrons) are removed from organic substrates in an oxidation reaction, NAD+ accepts 2 electrons and 1 proton; the remaining proton is released as free H+ ion.

An online handout I came across is along similar lines: http://web.mit.edu/7.01x/7.014/documents/Redox.pdf

I have also included a paper in which the red-ox reaction is explicitly stated (although it is given for flavin, they comment on the next paragraph that it holds true for iron as well):

http://www.jbc.org/content/262/25/12325.full.pdf+html

Perhaps this enzyme is an exception and in that case we need to consult a biochemist before proceeding any further but this is to the best of my knowledge...

Best, Duygu

Original comment by: ValWood

[gocentral]

• status: open --> closed-works-for-me

Original comment by: ValWood

[gocentral]

It is probably OK?

Dear Val,

The Rhea entry 28795 points out the reaction the way the GO entry does. So they are consistent across EBI platforms.

Duygu

Original comment by: ValWood