Editing Dehydrogenase (section)

=== FAD ===
[[File:FAD.svg|thumb|Flavin Adenine Dinucleotide]]
[[Flavin adenine dinucleotide|FAD]], or flavin adenine dinucleotide, is a prosthetic group (a non-polypeptide unit bound to a protein that is required for function) that consists of an adenine nucleotide and a flavin mononucleotide.<ref>{{Cite journal|title = Sequence-structure analysis of FAD-containing proteins|journal = Protein Science|date = 2001-09-01|issn = 1469-896X|pmc = 2253189|pmid = 11514662|pages = 1712–1728|volume = 10|issue = 9|doi = 10.1110/ps.12801|language = en|first1 = Orly|last1 = Dym|first2 = David|last2 = Eisenberg}}</ref>  FAD is a unique electron acceptor. Its fully reduced form is FADH<sub>2</sub> (known as the hydroquinone form), but FAD can also be partially oxidized as FADH by either reducing FAD or oxidizing FADH<sub>2</sub>.<ref>{{Cite journal|title = Riboflavin Metabolism|journal = New England Journal of Medicine|date = 1970-08-27|issn = 0028-4793|pmid = 4915004|pages = 463–472|volume = 283|issue = 9|doi = 10.1056/NEJM197008272830906|first = Richard S.|last = Rivlin}}</ref> Dehydrogenases typically fully reduce FAD to FADH<sub>2</sub>.  The production of FADH is rare.

The double-bonded nitrogen atoms in FAD make it a good acceptor in taking two hydrogen atoms from a substrate.  Because it takes two atoms rather than one, FAD is often involved when a double bond is formed in the newly oxidized substrate.<ref>{{Cite web|url=http://www.blobs.org/science/article.php?article=35#5|title=blobs.org - Metabolism|website=www.blobs.org|access-date=2016-03-01|archive-date=2016-02-01|archive-url=https://web.archive.org/web/20160201065212/http://www.blobs.org/science/article.php?article=35#5|url-status=dead}}</ref> FAD is unique because it is reduced by two electrons ''and'' two protons, as opposed to both NAD<sup>+</sup> and NADP, which only take one proton.