Sandbox Reserved 335: Difference between revisions
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[http://en.wikipedia.org/wiki/Cytochrome Cytochromes] are a class of heme-containing proteins found in bacteria and the mitochondria of eukaryotes.<ref name=main /> These proteins are generally membrane-bound and are known as respiratory pigments because they are involved in various electron transport systems in oxidative phosphorylation.<ref name="heme">PMID:14871137</ref> Cytochromes can be categorized into several different types, three of which are based on the type of heme group the cytochrome contains: cytochromes ''a'' and ''b'' contain heme ''a'' and ''b'', respectively, and cyt ''d'' contains a tetrapyrrolic chelate of iron.<ref name="cytd">MeSH http://www.nlm.nih.gov/cgi/mesh/2011/MB_cgi?mode=&term=Cytochrome+d</ref> Cytochrome ''c'' is named such because it contains the heme ''c'', but is mainly distinguished from cytochromes ''a'', ''b'' and ''d'' due to the heme being coordinated with the protein scaffold by cysteinyl residues covalently bound to either one or both of the heme's vinyl side chains.<ref name=heme /> | [http://en.wikipedia.org/wiki/Cytochrome Cytochromes] are a class of heme-containing proteins found in bacteria and the mitochondria of eukaryotes.<ref name=main /> These proteins are generally membrane-bound and are known as respiratory pigments because they are involved in various electron transport systems in oxidative phosphorylation.<ref name="heme">PMID:14871137</ref> Cytochromes can be categorized into several different types, three of which are based on the type of heme group the cytochrome contains: cytochromes ''a'' and ''b'' contain heme ''a'' and ''b'', respectively, and cyt ''d'' contains a tetrapyrrolic chelate of iron.<ref name="cytd">MeSH http://www.nlm.nih.gov/cgi/mesh/2011/MB_cgi?mode=&term=Cytochrome+d</ref> Cytochrome ''c'' is named such because it contains the heme ''c'', but is mainly distinguished from cytochromes ''a'', ''b'' and ''d'' due to the heme being coordinated with the protein scaffold by cysteinyl residues covalently bound to either one or both of the heme's vinyl side chains.<ref name=heme /> | ||
Cyt ''c'' has been split into four classes.<ref name=amb>PMID:1646017</ref> Class I contains soluble, low spin<ref name=main /> single domain C-type cytochromes, of which there has been at least six subclasses found in prokaryotes including [http://en.wikipedia.org/wiki/Desulfovibrio ''Desulfovibrio desulfuricans''], [http://en.wikipedia.org/wiki/Rhodospirillum_rubrum ''Rhodospirillum rubrum''], and ''Rhodothermus marinus''. Cyt ''c'' in this class have a single heme attached close to the N-terminus of the polypeptide, with a methionine residue being the sixth iron coordination site. Class II contains higher spin-state cytochromes ''c'', such as cyt ''c''', with the heme being attached closer to the C-terminus. Class III contains cytochromes with multiple heme groups; these proteins have lower redox potentials compared to the other three classes<ref name=amb />. Finally, Class IV is comprised of more complex proteins with higher molecular weights containing heme ''c'' as well as other prosthetic groups.<ref name=class> | Cyt ''c'' has been split into four classes.<ref name=amb>PMID:1646017</ref> Class I contains soluble, low spin<ref name=main /> single domain C-type cytochromes, of which there has been at least six subclasses found in prokaryotes including [http://en.wikipedia.org/wiki/Desulfovibrio ''Desulfovibrio desulfuricans''], [http://en.wikipedia.org/wiki/Rhodospirillum_rubrum ''Rhodospirillum rubrum''], and ''Rhodothermus marinus''. Cyt ''c'' in this class have a single heme attached close to the N-terminus of the polypeptide, with a methionine residue being the sixth iron coordination site. Class II contains higher spin-state cytochromes ''c'', such as cyt ''c''', with the heme being attached closer to the C-terminus. Class III contains cytochromes with multiple heme groups; these proteins have lower redox potentials compared to the other three classes<ref name=amb />. Finally, Class IV is comprised of more complex proteins with higher molecular weights containing heme ''c'' as well as other prosthetic groups.<ref name=class>Cookson DJ, Moore GR, Pitt RC, Williams RJP, Campbell ID, Ambler RP, Bruschi M, Le Gall J. Structural homology of cytochromes c. Eur J Biochem. 1978 Feb;83(1):261-75.</ref> | ||
=== ''Rhodothermus marinus'' === | === ''Rhodothermus marinus'' === | ||
