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I came across an article about flavodiiron proteins that are responsible for reducing ${\rm O}_2$ to ${\rm H}_2{\rm O}$ thereby protecting the anaerobic prokaryotes and some eukaryotes from oxidative stress. However, I am confused about the structure of that protein and its relation to heme proteins. Is this a heme protein?

The article I am reading is:

Di Matteo et al., The O2-scavenging flavodiiron protein in the human parasite Giardia intestinalis. J Biol Chem. 2008 Feb 15;283(7):4061-8. Epub 2007 Dec 12.

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No flavodiiron proteins are not haem proteins. See here for a simple depiction. Basically there is a flavin, and there are two iron atoms which go through a FeII/FeIII cycle during catalytic activity. These iron atoms are not held in haem, but rather via carboxylate ligands.

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No, Hemes are not proteins. They are porphyrins (large organic molecules) which are composed of four pyrrolic groups linked together. In the middle the coordinate the iron atom which is responsible for the activity. The combination of heme and iron is called a prosthetic group or co-factor. They are bound by the protein.

enter image description here

The image shows the Heme B from the Wikipedia.

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  • $\begingroup$ Right, thank you. However I meant heme proteins in the sense of en.wikipedia.org/wiki/Hemeprotein In other words, is flavodiiron protein a heme protein? $\endgroup$ – user9317 Sep 15 '14 at 20:24

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