Talk:Heme

Oxygen, binds to 1 atom or molecule?

Does each heme group bind one oxygen atom or one oxygen molecule (O₂)? AxelBoldt 21:09, 24 November 2005 (UTC)

Oxygen remains in the molecular form. It's one molecule of O2 for each haem molecule. JFW | T@lk 23:05, 24 November 2005 (UTC)

In many of the catalytic hemoproteins (P450 and peroxidases)during the chemical reaction a single oxgyen atom can be bound to a ferryl heme. For example in the peroxidase catalytic cycle compound I and compound II. --Bjsamelsonjones 19:33, 21 July 2006 (UTC)

Vinyl?

I'm not happy with the 'vinyl's in this article, and similar - god invented systematic naming for a reason, as there can be a fair degree of confusion. Will improve/edit later.

"Can I ask Lennert B to please place Roman numerals "I, II, III,IV" into the 5-membered pyrrole rings? Please begin with the top-left ring and continue clockwise. The "IV" will then appear within the bottom-left pyrrole. Designation of these pyrroles will allow much easier editing/additional information. There are two other hemes which should be presented, heme S and heme L. Heme L, of lactoperoxidase and eosinophil peroxidase (and also a related heme in myeloperoxidase) are extremely important in mammalian immunology. I am the Smith of - Caughey, Smythe, O'Keefe, Maskasky and Smith, (1975) J. Biol. Chem. "Heme A of Cytochrome c Oxidase" 250:7602-7622 and also a student of KG Paul who first published the correct structure of Heme C in Acta Chem. Scand.", (ML Smith, only this paragraph of request/comments).

Heme Degradation: Can you please replace the sheme for biliverdin to bilirubin with that from the article of biliverdin reductase-because the position of the vinyl groups is not matching (technically correct, but confusing). ->rotate bilirubin 180° — Preceding unsigned comment added by 134.169.45.80 (talk) 12:28, 7 October 2016 (UTC)

Apoprotein

Writing that the heme b is not covalently bonded to the apoprotein may be misleading, since most apoproteins are axially coordinated with the heme through a chemical bond (sometimes called a coordination bond).--Bjsamelsonjones 21:56, 21 July 2006 (UTC)

Only Heme c is covalently bonded (SS disufide bond) to the apoprotein. The other hemes and also heme c are bonded via coordination to the apoprotein, as you mentioned above. --Hoffmeier 10:37, 1 August 2006 (UTC)

Actually heme C is not bonded by disulfide bonds but with thioether bonds. I corrected the confusion in the table. The image also needs correction as the S atoms appear as if they belong to the heme. --kupirijo (talk) 12:50, 14 May 2011 (UTC)

Function

Writing that the main function of heme is to bind oxygen is incorrect. Hemes cage iron and allow the iron to bind ligands including oxygen, but also NO, peroxides, CO, etc. Hemes are also responsible for electron transport, which may be their original evolutionary role. --Bjsamelsonjones 21:56, 21 July 2006 (UTC)

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I'm thinking that someone who knows more about the topic than me about the dietary significance of heme/haem groups should add something about it here? I remember reading that vegetable sources only contain non-haem iron, making it harder for the human body to utilise (especially in the absence of vitamin C?) - is that right? --Oolong 02:46, 22 October 2007 (UTC)

What type of bond is N-Fe?

What type of bonds exist between the iron ion and the neighbouring nitrogen atoms? Are they covalent bonds involving electrons from the iron's lower shells?Dan Gluck 13:46, 22 July 2007 (UTC)

They are coordinate bonds from the nitrogen atoms. See Coordination complex. Ephemeronium (talk) 14:15, 8 April 2010 (UTC)

I think ALA dehydorgenase is wrong!

according to references it is ALA dehydratase... please change it from image that shows its biosynthesis. —Preceding unsigned comment added by PhysicalBiochemistry (talk • contribs) 13:51, 17 April 2008 (UTC)

ALA synthetase and ALA dehydrogenase

The picture has those 2 mistakes. I believe it is ALA synthase and ALA dehydratase. Someone mentioned ALA dehydratase.

Please check. —Preceding unsigned comment added by 197.224.0.187 (talk) 09:25, 14 November 2010 (UTC)

OI!

Could some kind soul please tell me, in the spirit of education, does it matter which sides of the haem group the globin or oxygen attatch to? For exmaple, in haem b, 3D structure here, does it go:

Globin |_> Oxygen

or

Oxygen |_> Globin

Where the subscript arrow indicates the direction the carboxylic acid groups are pointing. Clearly these two structures are different, but is it biologically significant which structure occurs? Which one appears most commonly, at least? — Preceding unsigned comment added by 82.44.98.35 (talk) 20:34, 20 March 2016 (UTC)

Heme as a meat replacement?

I can't say i know the science behind it, but I saw an article today mentioning the use of heme in new types of "meat alternatives." Looked like there was quite a bit money being put behind the idea, so I thought maybe it'd be worth adding a sentence or two to the health section of the article? Let me know what you think. Comatmebro User talk:Comatmebro 03:14, 20 July 2016 (UTC)

Heme= more than Fe(porphyrin)

It would be nice to cite definitions of heme outside of IUPAC, which indicates that one or more axial ligand is required. I get the feeling that others see things differently. Another issue is that some editors seem to think that square planar Fe(porphyrin) centers exist, which they do not in the condensed phase.--Smokefoot (talk) 14:28, 1 November 2017 (UTC)