Talk:Heme A

Is this the right structure??

PubChem has a different structure listed as [heme a http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=5489981]

Is the one on Wikipedia the right one? Notice the saturated versus unsaturated chain. I believe the SATURATED chain is [the correct one since it is marked with the MESH Annotation http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=5288529 ] but the unsaturated one isn’t. --ChemSpiderMan (talk) 04:34, 13 January 2008 (UTC)[reply]

I think you`re right with the saturated chain. I also think, that both carboxylic chains should be one -CH2- group longer. Efka.cz (talk) 16:21, 13 January 2008 (UTC)[reply]

I agree with you regarding the length of the chains too. See my report online regarding this compound here: http://www.chemspider.com/docs/wikipedia/Wikpiedia_Review_project_011208.pdf--ChemSpiderMan (talk) 16:58, 13 January 2008 (UTC)[reply]

Both of the structures in PubMed are incorrect; the structure in Wikipedia is correct. This might be due to a reference, by whoever placed the PubMed structures, to earlier work done in the 1960s by a German group, that proposed an incorrect structure with a fully saturated alkyl "chain" at position 2 of Pyrrole I. Perhaps the incorrect structures were also used in PubMed by analogy to the many chlorophylls? One of the structures listed in PubMed also presents iron as Fe4+ which is just weird. In 1979 I ran the C13 NMR of heme A where the unsaturated carbons of the long alkyl side chain are very easily detected. Wikipedia is correct.