Talk:Flavin adenine dinucleotide

message: Yes, FAD is a dione... let me think now. c.f. Quinone
--Rolodexx (talk) 23:03, 16 December 2011 (UTC)
thread_title:  Nomenclature? 

message: 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)
replies: text: 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)
thread_title:  FADH<sub>2</sub> In ATP Equivalents 

message: :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)
thread_title:  Move? 

message: 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)
thread_title: Winter 2015 Class Project Page Expansion

message: Substituted at 05:10, 13 May 2016 (UTC)
thread_title: Assessment comment

message: 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)
thread_title: Electron transfer reactions: confusing CPR with CP-450

message: 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
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. https://pubs.acs.org/doi/10.1021/jp404938u#:~:text=The%20enthalpy%20of%20hydrogenation%20of,order%20to%20analyze%20its%20aromaticity.&text=It%20was%20found%20that%20uracil,character%20in%20the%20gaseous%20phase.https://en.wikibooks.org/wiki/Structural_Biochemistry/Nucleic_Acid/Nitrogenous_Bases#:~:text=Of%20the%20nitrogenous%20bases%2C%20adenine,are%20one%20ring%2Daromatic%20compounds.
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)
thread_title:  Is FADH2 aromatic?