Talk:Phosphocreatine

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Mistake in phosphocreatine 3d balls file[edit]

I have removed file because there lacks 1 hydrogenium that should be connected to nitrogenium. —Preceding unsigned comment added by 89.77.213.20 (talk) 23:36, 18 January 2008 (UTC)[reply]

Where? The 3D model does not match the skeletal structure exactly—they look like different tautomers—but I don't see any missing hydrogens. Fvasconcellos (t·c) 23:44, 18 January 2008 (UTC)[reply]

→Sorry! There is no such a thing called "hydrogenium" and "nitrogenium" Dossge (talk) 15:15, 3 July 2015 (UTC)[reply]

Chemical structure[edit]

There are several errors in the structure of creatine phosphate. First, at pH 7 the carboxylic acid is in its deprotonated -COO:(-) state; likewise, the phosphate group is, for the most part, fully deprotonated at pH 7, OPO3(2-). Second, the phosphorous should be attached to the single-bonded amine group (-NHPi-), and not the double-bonded imine group. Finally, at pH 7 the imine is in its protonated =NH2(+) state. 86.40.100.222 (talk) 09:22, 28 May 2010 (UTC)Todd Silverstein, Willamette Univ., Salem, OR, USA[reply]

It is conventional to draw amino acids this way with neutral functional groups, rather than the zwitterionic form. See for example the PubChem page for this this compound: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=587 As for the location of the phosphate group, either of the two representations is fine - they are simply tautomers of each other. ChemNerd (talk) 11:21, 28 May 2010 (UTC)[reply]

Hello, The first guy who commented was right about the phosphonate group connected to the amino group instead of imino. And absolutely no - there is no tautomery - that is actually why the molecule is energetically high - because it is not a resonance structure. that is where the Gibbs energy is hidden and why hydrolysis yields so much energy. Therefore the structure is incorrect. — Preceding unsigned comment added by 94.112.1.118 (talk) 13:27, 26 May 2011 (UTC)[reply]

The two structures are tautomers. It seems that some databases such as PubChem (link) depict it as one tautomer, and others such as Chemical Abstracts (link) depict it as the other. I think CA tends to be a more reliable source, and this tautomer also matches the 3D structure image, so I have switched File:Phosphocreatine.png as you suggest. -- Ed (Edgar181) 13:39, 26 May 2011 (UTC)[reply]

Hello again, thank you for correcting the structure edgar. I have to ask though. you claim the two structure are tautomers, however from my point of view these two structures cannot change to each other under normal physiological conditions. The reason why this molecule can be used to create a ATP molecule from ADP is because it "contains" high energy, which is "hidden" in the inability of the Phosphocreatine to resonate. at least that is how i have always been taught and how i read it. thank you very much for answer George.

This is how guanidinium groups resonate:

What you've been taught appears to be wrong.

Ben (talk) 22:57, 29 May 2011 (UTC)[reply]

The crystal structure of the disodium salt shows the connectivity is correct. The PO(OH)₂ group is fully deprotonated to PO₃⁻ and the CO₂H group is likewise deprotonated to CO₂⁻. The guanidine group is protonated, so we have a zwitterionic structure (guanidinium + "phosphate" + carboxylate). Obviously, this doesn't tell us the equilibrium structure in solution at pH 7, but it suggests the guanidine part is protonated. With a guanidinium group, there is resonance between three possible iminium structures. --Ben (talk) 18:08, 26 May 2011 (UTC)[reply]

According to the pubchem and in John Elks book, a different chemical structure is provided for Fosfocreatinine: https://pubchem.ncbi.nlm.nih.gov/compound/71214#section=Top There has been a cyclization (-H2O) between the carboxylic acid and the imine nitrogen. --79.74.10.238 (talk) 12:23, 14 May 2016 (UTC)[reply]

I believe the two forms are in equilibrium, as for creatine and creatinine. --Ben (talk) 10:51, 17 May 2016 (UTC)[reply]

Possible mistake in the article[edit]

In the second sentence it says that phosphocreatine donates a phosphate group to ADP to make ATP. In the third sentence it says that this process is catalyzed by creatine kinase. This sounds like a mistake to me; I would expect an enzyme named creatine kinase to phoshorylate creatine, not remove a phosphate from phosphocreatine. When I clicked on the link to creatine kinase it confirmed my suspicion that creatine kinase phoshporylates creatine. If this is what the author meant I do not think it is clear in the article. Jasonbholden (talk) 04:26, 7 April 2008 (UTC) As I understand it: catalysts don't affect the position of a equilibrium reaction, only the time it takes to get there. As such, they affect the forward and reverse reactions equally. There's no such thing as a catalyst which works for A > B and not B > A. 86.178.126.150 (talk) 23:23, 29 March 2013 (UTC)[reply]

Assessment comment[edit]

The comment(s) below were originally left at Talk:Phosphocreatine/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.

How much ATP is produced per creatine phosphate molecule? —The preceding unsigned comment was added by 148.61.13.4 (talk • contribs) 23:12, 19 February 2007.

Last edited at 19:28, 13 March 2007 (UTC). Substituted at 02:53, 30 April 2016 (UTC)