Cytochrome c: Difference between revisions

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<scene name='Sandbox_Reserved_335/Heme/1'>'Figure 1. The heme group of monoheme cytochrome ''c'' purified from ''Rhodothermus marinus''</scene>
<scene name='Sandbox_Reserved_335/Heme/1'>'Figure 1. The heme group of monoheme cytochrome ''c'' purified from ''Rhodothermus marinus''</scene>


All members in the C-type cytochrome superfamily contain a heme prosthetic group that is covalently attached to the protein via two thioether bonds to cysteine residues. Most cytochromes ''c'' occur in a <scene name='Sandbox_Reserved_335/Motif/1'>CXXCH motif</scene> where the histidine residue is one of the two axial ligands of the heme iron.<ref name=main>PMID:18855424</ref><ref name=heme /> In monoheme cytochromes ''c'', the other axial position may be left vacant or be occupied by histidine or methionine residues; however, it can sometimes be occupied by cysteine or lysine residues.<ref name=main />. In ''Rm''cyt''c'', XX represents a threonine (Thr46) and an alanine residue (Ala47) that help form the loop 2 structure.
All members in the C-type cytochrome superfamily contain a heme prosthetic group that is covalently attached to the protein via two thioether bonds to cysteine residues. Most cytochromes ''c'' occur in a where the histidine residue is one of the two axial ligands of the heme iron.<ref name=main>PMID:18855424</ref><ref name=heme /> In monoheme cytochromes ''c'', the other axial position may be left vacant or be occupied by histidine or methionine residues; however, it can sometimes be occupied by cysteine or lysine residues.<ref name=main />. In ''Rm''cyt''c'', XX represents a threonine (Thr46) and an alanine residue (Ala47) that help form the loop 2 structure.


[[Image:heme.gif |frame|left| Figure 2. The tetrapyrrolic heme prosthetic group that can either be covalently attached to or closely associated with various proteins, such as cytochromes and other globin proteins. In ''Rm''cyt''c'', R2 is an ethyl group covalently attached to Cys 45, and R3 is a methyl group covalently attached to Cys48.]]
[[Image:heme.gif |frame|left| Figure 2. The tetrapyrrolic heme prosthetic group that can either be covalently attached to or closely associated with various proteins, such as cytochromes and other globin proteins. In ''Rm''cyt''c'', R2 is an ethyl group covalently attached to Cys 45, and R3 is a methyl group covalently attached to Cys48.]]