Talk:Flavin adenine dinucleotide

Nomenclature?

Yes, FAD is a dione... let me think now. c.f. Quinone

--Rolodexx (talk) 23:03, 16 December 2011 (UTC)

FADH₂ In ATP Equivalents

Someone needs to cite a source for the ATP equivalents because I'm 99% sure it's wrong. I'm looking at a Figure 17-7 for those who have Voet-Voet's Biochemistry (2e). If I'm reading it right, the electrons are passed from one FADH₂ in Complex II to CoQ. 1.0 ATP is generated from the transfer to Cytochrome C via Complex III, and 1.0 more following the transfer to water, via Complex IV for a total of 2.0 ATP equivalents. --Michael (talk) 19:28, 9 March 2009 (UTC)

There are two schools of thought regarding the ATP equivalence of NADH and FADH2. Orthodox biochemists believe that transfer of an electron pair from NADH to ½ O2 generates 3 ATP, and an electron pair from FADH2 generates 2 ATP. On the other hand reformed biochemists accept 2.5 ATP from NADH and 1.5 from FADH2. The orthodox version springs from the idea that the number of ATPs related to three distinct sites that coupled electron transfer to ATP synthesis, and therefore the final total had to be an integer, even though almost all orthodox now accept the chemiosmotic model as the mechanism of oxidative phosphorylation. In the chemiosmotic model, the electron transport chain pumps H+ across the inner mitochondrial membrane (eukaryotes) or cytoplasmic membrane (prokaryotes) creating an H+ gradient across the membrane. The H+ gradient then drives the ATP synthase. In this two step process, there is no requirement for the number of ATP generated per NADH or FADH2 to be an integer. Experimental measurements of oxidative phosphorylation typically max out at 2.5 ATP per NADH and 1.5 per FADH2, and this was conveniently rounded up to the next higher integer by those of orthodox faith. The consensus is that 6 H+ are pumped out per FADH2 oxidized in mitochondria (10 per NADH) (bacterial systems are a little different) and 3 H+ are required for the synthesis of one ATP from ADP and phosphate. However, the ATP is generated in the mitochondrial matrix, and for the most part, is used in the cytoplasm. It turns out that there is a cost to deliver ATP to the cytoplasm. The entry of phosphate and ADP3- to the mitochondrion in exchange for ATP4- leaving dissipates one more H+. As a result, the overall cost of one ATP synthesized and delivered is 4 H+. 6 H+ per FADH2 can therefore make and deliver 1.5 ATP. See L.Stryer, Principles of Biochemistry 5th Ed., W H Freeman 2008, or Nelson and Cox, Lehninger's Principles of Biochemistry 5th Ed. WH Freeman 2008.96.54.32.44 (talk) 06:23, 5 December 2010 (UTC)

Perhaps someone could add a section about the 'ability' of this molecule to accept one electron so that it becomes a half-reduced (relatively stable) radical. This way it connects metal electron transfer with organic electron transfer. —Preceding unsigned comment added by 80.126.164.111 (talk) 22:48, 27 October 2009 (UTC)

Move?

The following discussion is an archived discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a move review. No further edits should be made to this section.

The result of the move request was: page moved. Rifleman 82 (talk) 14:29, 22 August 2012 (UTC)

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Moved per lack of opposition and in conformance with Wikipedia:Article_titles (abbreviations). --Rifleman 82 (talk) 14:29, 22 August 2012 (UTC)

FAD → Flavin adenine dinucleotide –

• FAD is too generic and should be a redir to Fad. -- Alan Liefting (talk - contribs) 22:17, 15 August 2012 (UTC)
• Needs a full discussion, IMO. I don't think it's obvious that someone typing in the all caps "FAD" is looking for our article on fads. Jenks24 (talk) 02:32, 16 August 2012 (UTC)
• Comment, if FAD doesn't go to this article or to some similar article, then it should go to FAD (disambiguation). It should not be a redirect to Fad. — P.T. Aufrette (talk) 17:29, 16 August 2012 (UTC)
• Support "FAD" should be disambiguated. -- 76.65.128.252 (talk) 06:39, 17 August 2012 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

Winter 2015 Class Project Page Expansion

We are working on expanding the coverage of this page as part of a class from January to February 2015. This is a rough outline of our planned additions:

• Basic Physical and Chemical Properties
  • structure description
  • basic redox equation and description
  • physical appearance
  • UV spectrum information/fluorescence
• Mechanism
  • mechanism figure/electron movement
• Cellular Roles/Functions of FAD/Biological Importance
  • estimated concentration in cells
• Glycolysis/TCA
  • include information about FAD to ATP equivalents (as per talk page)
• Biosynthesis of FAD
  • including riboflavin family members and vitamin B importance
• Flavoprotein Examples/Biological Significance
• Role in Medicine/Therapeutics
  • ex. http://www.ncbi.nlm.nih.gov/pubmed/20210484
• History
  • link to page about Vincent Massey

Thanks! Gk2015 (talk) 00:09, 19 January 2015 (UTC)

As of 2/25/15, we just uploaded our additions to the page. Gk2015 (talk) 01:43, 26 February 2015 (UTC)

Picture size: pictures are too big to be helpful and obscure much of the page — Preceding unsigned comment added by SireWonton (talk • contribs) 16:53, 27 October 2015 (UTC)

Assessment comment

The comment(s) below were originally left at Talk:Flavin adenine dinucleotide/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

Rated "high" as high school/SAT biology content - tameeria 19:53, 22 February 2007 (UTC)

Substituted at 05:10, 13 May 2016 (UTC)

Electron transfer reactions: confusing CPR with CP-450

This section seems to imply that CPR and CP-450 are the same protein, and contain two flavins and a heme. It is my understanding that CP-450 contains only heme, and CPR (Cyt P450 Reductase) contains FMN and FAD which are involved in transferring electrons from NAD(P)H to CP-450. Could someone verify this and update the section? Eaberry (talk) 17:57, 21 January 2017 (UTC)

Is FADH2 aromatic?

In the section Properties, it states

> FAD is an aromatic ring system, whereas FADH2 is not.

I've been able to trace this to a book quote, Bioprocess Engineering, which states

> FAD is an aromatic ring (flavin group) system, whereas FADH2 is not.

The image

FAD FADH2 equlibrium

clearly shows an "aromatic" benzene group on the left hand side of both molecules, and the right hand side of FADH2 is Uracil, which although the article on uracil doesn't suggest it is aromatic, there are citations that support uracil's aromaticity, e.g.

I haven't been able to uncover the truth of the assertion one way or the other elsewhere in primary literature, and think this should be a "citation needed" or some other qualifier until this can be verified in a conclusive matter. I have blogged about this question elsewhere, e.g. https://www.quora.com/Is-FADH2-aromatic/answer/Matt-Harbowy

MatthewEHarbowy (talk) 22:08, 25 June 2020 (UTC)

References