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This question already has an answer here:

I have gone through various sites and some say there is NADPH2 and some say there is no NADPH2 there's only NADP+ ...WHich is the correct view....Please dont mark this answer as duplicates since I have asked a similar question related to photosynthesis in the past but there too I have not received any satisfactory answer bythe community .

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marked as duplicate by rg255, AliceD, James, WYSIWYG May 1 '16 at 6:54

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

  • $\begingroup$ If you didn't got satisfactory answers, you should work on your question. You can always edit them (unless you totally change the question after you got an answer). $\endgroup$ – Chris Apr 29 '16 at 14:07
  • $\begingroup$ Might be useful if you could give links to sites that use NAPH2. $\endgroup$ – David Apr 29 '16 at 17:11
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I answered this implicitly in a comment to my answer to: Light and Dark Reaction of photosynthesis?. Anyway:

There is no such thing as NADPH2. There is only NADP+ and NADPH. Consult Wikipedia or a reputable text such as Berg.

The nicotinamide portion of NADP that undergoes oxidation and reduction is exactly the same as in NAD. The changes undergone are:

NAD(P) redox

The error either comes from confusion with the other redox cofactor, FAD / FADH2, or the fact that two electrons are involved in the reduction of NADP:

NADP+ + H+ + 2e → NADPH

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  • $\begingroup$ Apologies that my initial answer was just in terms of NAD, not NADP. Fixed now. $\endgroup$ – David Apr 29 '16 at 16:15
  • $\begingroup$ A factor that sometimes is confusing is that both hydrogens at the redox site in NADP(H) are equivalent. So it is possible that one hydrogen gets added in the reduction, but the other hydrogen is donated in the next oxidation, and therefore deuterium tracing studies of NAD(P)H will give both +1 and +2 deuterium isotopes. This is sometimes mistakenly interpreted as "NADPH2". $\endgroup$ – Roland Apr 29 '16 at 16:55