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What vitamin is NAD made from?
The structure that has been given is incomplete. The hydroxyl groups on the ribose moiety are missing.
Plants surely do not produce ADP through photosynthesis, but instead like animals through respiration. Plants produce sugars through photosynthesis that can then be metabolised to produce ATP->ADP etc? -- Murphyen 20:14, 14 May 2006 (UTC)
few questions how is it formed? how is it transported? how is it cycled? how is it equivalent to ATP formation? -- M siterman 09:18, 17 May 2006 (UTC)
I go this mail today. Tim Vickers 23:58, 11 September 2007 (UTC)
This is a reasonably good article, and critically important for biochemistry, but there are problems significant enough in the article that I have failed it at this time.
This article is very well written and informative. The use of illustrations is also very good, and greatly helps the reader to understand the topic. I believe all of the issues raised by EncycloPetey above have been addressed (though I did find a few minor copyediting things to fix, but nothing major). One minor suggestion; I wonder if the biosynthesis section should be moved to immediately after the properties section, as it might help to order it by starting a discussion of the properties, then talk about how it's made, then discuss it's function? Overall, though, this article is in excellent shape, and meets the Good Article criteria. Good work! Dr. Cash ( talk) 15:31, 6 December 2007 (UTC)
I changed the wording, hoping that the first two are not so closely linked that they required the previous wording. Tony (talk) 23:33, 8 December 2007 (UTC)
Here is a picture, but I have no idea where to fit it into the article.
Narayanese (
talk) 08:19, 23 December 2007 (UTC)Found a spot for it.
Narayanese (
talk) 08:38, 23 December 2007 (UTC)Aw, I realised there are no hydrogens on the carbons
Narayanese (
talk)
08:43, 23 December 2007 (UTC)
I've created another 3D model of NAD+, based on PDB 2FM3. It's a stick model, which looks the cleanest, and even has hydrogens.
If anyone wants to put it in the article (is there space?), it's here!
Ben ( talk) 14:53, 10 January 2008 (UTC)
It might be a good idea to mention that when reduced, there are two possible forms of NADH: A form and the B form. I just read it on Lehninger's biochemistry textbook that says different enzymes add the hydrogen to different locations on the nucleotide ring. Keith Galveston ( talk) 12:57, 7 March 2008 (UTC)
Counting the charges (2 phosphate -ve charges, 1 quat N+), the structure is not neutral, making it an ion rather than a substance. On the other hand, SMILES gives 1 neutral phosphate (OH), making it charge zero. Formula and MW are for the neutral compound as well.
The consensus at wikiproject chemistry is that we prefer neutral species as far as possible, and that chemboxes should be for substances, not ions. That means that the image in the box should be updated. I can do it quite easily, but I want to check if there are any violent objections here first.
I can generate the image easily too, but I need to know which phosphate is to be protonated. I do believe that it should be an equilibrium, but the image is a depiction of reality rather than reality itself). -- Rifleman 82 ( talk) 19:14, 7 March 2008 (UTC)
They look like an advertisement for some book of his in alternative medicine, and don't belong the the article Narayanese ( talk) 14:23, 28 June 2008 (UTC)
What is the proper way to pronounce "NADH" or "NAD+"? Do you spell out the abbreviation or do it in some other way? Do you say "En-Ay-Dee Plus" for NAD+ or something else?- 132.239.5.102 ( talk) 20:01, 3 June 2009 (UTC)
Hi there. A while back I came across the sup template, and I think it could be pretty useful here given the number of instances of "NAD+". Compare:
The template takes up far less space in the text while editing. I just wanted to make sure there isn't some drawback to using it here that I'm not aware of; otherwise I'll go ahead and make the switch. — tk tk tk 02:22, 26 November 2009 (UTC)
The article has again appeared on the front page. Has it been greatly upgraded recently? (I'm planning to translate). -- CopperKettle 08:57, 26 November 2009 (UTC)
The discussions of NAD+/NADH ratios in "Concentration and state in cells" and "Role in redox metabolism" seem to contradict each other. Which is it? Weighted towards NAD+ or roughly equal? (And, yes, it's somewhat different in the mitochondrion... I added the word 'cytoplasmic' to the first of these sections to clarify its quoted 700x figure.)
The article lists the redox couple of NADH/NAD+ as –0.34V, but I think you are going to have to be more specific about conditions before this fact has any meaning. While most potentials are measured against the Standard hydrogen electrode there are many other alternatives which things are commonly measured against each of which has a very different definition of 0.0 V. By just assuming something is referenced to the standard hydrogen electrode I have been burned before. Also solvent and temperature are important for potentials. This is especially true for the NADH/NAD+ couple which has been shown to very by more then a full volt just based on whether it is in acidic or basic media, see: Karyakin, A. A.; Ivanova, Y. N.; Karyakina, E. E. Electrochemistry Communications, 2003, 5, 667-680.
As a side note can –0.34V really be considered a strong reductant? In aqueous media strong reductants are usually considered to be things like Li/Li+ which is < –3.0 V, almost a full order of magnitude stronger then NADH/NAD+. Obviously, NADH being a terminal reductant in most organisms means that it is just about the strongest reductant commonly found in biology. However, being a strong reductant by biological standards or perhaps under biophysical conditions (which one, or is it both?) is an important distinction from the more general label "a strong reductant" that is found in this article.
131.215.32.217 ( talk) 21:41, 17 June 2010 (UTC) Nat
131.215.32.217 ( talk) 00:24, 18 June 2010 (UTC) Nat
131.215.32.217 ( talk) 22:30, 21 June 2010 (UTC)Nat
Anyhow a reported value for reduction potential should be at Standard State, which for biochemistry is defined as aqueous state, 1 M concentrations of reactants and products, 25 C, 1 atm pressure, and pH 7.0 (which means that [H+] is 10e-7 M rather than 1 M) (ref Tinoco, Sauer and Wang, Physical Chemistry Principles and Applications in Biological Sciences pp.139-140, Prentice Hall, New Jersey 1995). Of course, it's usually not possible to do biochemical reaction with 1 M concentrations, so realistic concentrations are used and the standard reduction potential is calculated by means of the Nernst Equation. The consensus value for the standard reduction potential of NADH is -0.32 V and for NADPH -0.324 V. In an oxygenated eukaryotic cell, cytoplasmic [NADH]/[NAD+] is about 0.002, effective E' = -0.24 V, whereas mitochondrial [NADH]/[NAD+] is about 0.1, effective E' = -0.29 V (Biochemistry, A.H. Lehninger, Worth, NY 1975). In metabolism, NAD+ typically participates as the oxidant, the resulting NADH being passed to the oxidative phosphorylation system for generation of ATP. [NADPH]/[NADP+] is about 100, effective E' = -0.38 V, and in metabolism, NADPH is used primarily as a reductant in biosynthetic reactions. Because of the different ratios and reduction potentials NADPH and NADH are not used interchangeably, and it costs the energy equivalent of one ATP to get NADH to reduce NADP+. For comparison with other metabolic reactions, the standard reduction potential for the acetic acid/acetaldehyde couple is -0.581 V, for acetaldehyde/ethanol is -0.197 V, for pyruvate/lactate (ketone/secondary alcohol) is -0.18 V and for fumarate/succinate (reduction of C=C bond) +0.031 V. 96.54.32.44 ( talk) 07:53, 4 December 2010 (UTC)
The physical and chemical properties paragraph starts with the sentence 'Nicotinamide adenine dinucleotide, like all dinucleotides, consists of two nucleotides joined by a pair of bridging phosphate groups.' Actually dinucleotides from DNA and RNA would only have a single bridging phosphodiester group linking 3'- of one ribose to the 5'- of the other ribose. The second phosphate would be a phosphomonoester attached to one of the other 3'- or 5'- hydroxyls. NAD+ also differs in that the linkage is 5'- to 5'-, and contains a high energy phosphoanhydride bond. 96.54.32.44 ( talk) 01:33, 4 December 2010 (UTC)
The lede wording is presently unclear whether the title "Nicotinamide adenine dinucleotide" refers to NAD+, to NADH, or to both. The normal form is to give the full name (ABBR) before any further use of the abbreviation.
http://www.sciencedaily.com/releases/2013/12/131219130738.htm — Preceding unsigned comment added by 76.176.108.8 ( talk) 03:36, 20 December 2013 (UTC)
In addition to addressing my own concerns, the following proposed set of edits also addresses the concerns of two previous editors, here [1] ("Description...") and here [2] ("Title"), as well as others; see above.
The title refers to one molecule, but by virtue of redirects and content, the article aims to be about two structurally, chemically distinct molecules. Hence the structure and information given in the infobox is either incomplete or incorrect (and so inherently confusing). To present one structure to cover both molecules, and give beneath it two CAS numbers—clearly we are not putting ourselves in the shoes of a nonspecialist coming to this page. Having both NAD+ and NADH searches come to this same page, with its opening and lede and superficial features (including the single inbox and single structure) is tremendously confusing to any but those already knowing the structures and subject.
To address this:
"The term nicotinamide adenine dinucleotide refers to either a reduced or oxidized form or a pair of molecules, abbreviated NAD+ and NADH, respectively. As a pair, they serve as coenzymes—small organic molecules bound to enzymes, and assisting in their catalyses—and so are found in all living cells. Each is a "dinucleotide", consisting of two nucleotides joined through a unique pyrophosphate (phosphoanhydride) diester linkage between the 5'-hydroxyl group of the ribose ring of each nucleotide. One nucleotide is an adenine-type, and the second an unusual ribofuranosyl nicotinamide (derived from dietary niacin, a vitamin).
In metabolism, NAD+ and NADH are involved in redox reactions, the reduced form (NADH) being generated when an enzyme's substrate is oxidized, the oxidized form (NAD+) being generated when a substrate is reduced. In this way, NAD+ is an oxidizing agent (accepting electrons from other molecules) and NADH is a reducing agent (donating electrons to other molecules); because they are molecules, and can diffuse away from the original enzyme and site of reaction, they can serve to shuttle electrons between pathways in biosynthesis. The "business end" (see ( [3]) of the NAD+ oxidant is the substituted pyridinium cation of its nicotinamide moiety, which can be reduced under biological conditions to the corresponding 1,4- dihydropyridine; the midpoint potential of the NAD+/NADH redox pair is −0.32 volts (STP), making NADH a potent biological reducing agent that can be used, after it is generated, to accomplish many other reactions in metabolism. Hence, a central aim of primary metabolism (e.g., the citric acid cycle and other pathways), besides the production of particular metabolic intermediates, is the generation of NADH, as well as ATP, for use in other chemical reactions."
An additional minor point well addressed by many of our inorganic brethren (editors) but missed often by the organic and biochem of the flock: 3D representations of molecules are only rigourous, and so meaningful, if they include details in the legend as to how they were derived. If the 3D ball-and-stick form of the NAD+ molecule shown in the infobox is a representative of an ensemble of low energy structures derived by MM2 or MD computations, say so, and give some detail (summarizing more complete information on the image page at Wikimidia Commons). Complete the legend by saying why the given pose was chosen and presented. A computed structure, if good, is WP:OR at best, and at worst is simply nonsense. Make clear that the 3D images you post are not nonsense; see [4] and [5] by way of example.
Finally, conceptually, an opinion: to elevate NAD+ over NADH, in any way—choosing it, of the two molecules, to make preeminent (via structure, direction reactions written, etc.)—is also worth review. From an utterly unbiased perspective, considering extremophiles surviving in environments at the limits of oxidizing and reducing, neither of the pair can be given primacy. But, given the fact that the overall thrust of metabolism—and a very critical chemical milestone that the origin of life demanded—is the need for a mobile form of reducing equivalents to perform the work of biosynthesis (accomplished as this was, in NADH), says which I would emphasize. In an iron-rich oxidizing environment, the lessor problem is how to get things oxidized; the hard problem is gettng them reduced, and reversibly, via a mobile, quasistable organic agent. In this sense, the NAD+/NADH couple, and its uses, constitute a chemical miracle (RD, forgive my loose use of language).
Sorry to rain on the parade; I am sure relative to many WP articles this is in very good shape, and worth the given accolades. But, it is not yet clear with regard to the aspects indicated above. Anytime a chemical infobox has to present two CAS numbers, and an article shows one structure at its top, after being referred via two molecule searches... any real chemist is going to say Danger, Will Robinson ( [6]). Le Prof Leprof 7272 ( talk) 08:50, 28 June 2014 (UTC)
The article distinguishes two classes of enzymes depending on whether the hydride is delivered "above or below the plane" of C4 on NAD+. That directional terminology seems completely dependent on the perspective from which one considers NAD+. There is either some "standard" (but unexplained in this area of the article) orientation, or else it is in reference to how NAD+ is bound to some other entity. But none of this is explained in this area of the article.
At minimum, I think there should be a diagram of NAD+ with identified "above"/"below" (or front/back, or whatever is appropriate) or else a diagram NADH with two H identified as to which would come from class-A vs class-B. I assume the reaction occurs with a "stack" of enzyme/NAD+/substrate (or enzyme/substrate/NAD+?) and that the different classes lead to binding of opposite faces of the nicotinamide ring as the "reason" for the facial distinction. A clear illustration of this could be 3D side perspectives of an example of each, with highlighting of the nicotinamide ring and the hydride to be transferred from the other substrate. DMacks ( talk) 05:59, 28 November 2014 (UTC)
The comment(s) below were originally left at Talk:Nicotinamide 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.
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Last edited at 18:27, 23 December 2007 (UTC). Substituted at 01:14, 30 April 2016 (UTC)
The diagram for De Novo production has the following caption: "Some metabolic pathways that synthesize and consume NAD+ in vertebrates. The abbreviations are defined in the text."
Please correct me if I'm wrong, but it appears as if "NMN", or Nicotinamide mononucleotide, has not been defined within the text. Otherwise, all other abbreviations appear to have been defined within the text.
Thank you for your kind attention. Zyvov 06:29, 31 December 2016 (UTC) — Preceding unsigned comment added by Zyvov ( talk • contribs)
The following was added here, and edit warred back in here:
Human aging is characterized by a gradual deterioration of physiological and biochemical function. [1] Limited research data suggests that NAD+ levels decreases with increasing age. [2] Preliminary results suggests that supplementing key NAD+ intermediates, such as nicotinamide mononucleotide (NMN) and nicotinamide riboside (NR), might rise NAD+ levels in both mice and humans. [3]
References
Moved here for discussion. More comments anon. Jytdog ( talk) 00:48, 9 February 2017 (UTC)
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NAD is called Factor V in bacteriology as mentioned in the article. Factor V should have a disambiguation page containing NAD. Ddhelmet ( talk) 15:17, 19 December 2017 (UTC)
The characterization of the substance as a dinucleotide, nicotinamide adenine dinucleotide, implies that nicotinamide is a nucleotide, yet definitions of a nucleotide universally refer to a role in nucleic acids where nicotinamide does not play. Wikipedia's article on nucleotides includes "nicotinamide" nowhere.
This calls for some explanation.
Charlie McKeon ( talk) 15:32, 27 December 2018 (UTC)
It says, "In appearance, all forms of this coenzyme are white amorphous powders that are hygroscopic and highly water-soluble" This makes me wonder about the taste. It is sweet like ribose or bitter like niacin? I wondered because supplements like NMN are molecularly similar and might be suitable for use in food or drink. — Preceding unsigned comment added by 2600:6C55:7001:400:3526:88A0:5723:F775 ( talk) 22:29, 27 January 2019 (UTC)