Sandbox Reserved 335: Difference between revisions
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'''Cytochrome ''c''''' (cyt ''c'') is a superfamily of proteins belonging to the class of [http://en.wikipedia.org/wiki/All-α_proteins all-α proteins] with a core of helices and a covalently-bound [http://en.wikipedia.org/wiki/Heme heme prosthetic group].<ref>PMID:11697912</ref><ref name=main /> The cytochrome ''c'' superfamily contains many different families including monodomain and multi-domain C-type cytochromes (ex. [http://proteopedia.org/wiki/index.php/1etp cyt c4], a | '''Cytochrome ''c''''' (cyt ''c'') is a superfamily of proteins belonging to the class of [http://en.wikipedia.org/wiki/All-α_proteins all-α proteins] with a core of helices and a covalently-bound [http://en.wikipedia.org/wiki/Heme heme prosthetic group].<ref>PMID:11697912</ref><ref name=main /> The cytochrome ''c'' superfamily contains many different families including monodomain and multi-domain C-type cytochromes (ex. [http://proteopedia.org/wiki/index.php/1etp cyt c4], a diheme C-type cytochrome, and [http://proteopedia.org/wiki/index.php/2ozy NrfB], a pentaheme C-type cytochrome). This page focuses mainly on the cytochrome ''c'' superfamily, briefly discussing various types within the superfamily. The monoheme cytochrome ''c'' purified from ''Rhodothermus marinus'' will be discussed in greater detail than other C-type cytochromes. | ||
== Introduction == | == Introduction == | ||
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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 '''CXXCH motif''', where a histidine residue is one of the two axial ligands of the heme iron.<ref name=main>PMID:18855424</ref><ref name=heme /> The other axial position, in monoheme cytochromes ''c'', may be left vacant or be occupied by histidine or methionine residues, but can sometimes be occupied by cysteine or leucine residues.<ref name=main />. The typical monoheme cyt ''c'' fold is formed by helices <scene name='Sandbox_Reserved_335/Helices/1'>A, C, and E</scene>. In ''Rm''cyt''c'' there are seven α-helices that are folded around the porphyrin ring, all connected by random coils.<ref name=main /> | 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 '''CXXCH motif''', where a histidine residue is one of the two axial ligands of the heme iron.<ref name=main>PMID:18855424</ref><ref name=heme /> The other axial position, in monoheme cytochromes ''c'', may be left vacant or be occupied by histidine or methionine residues, but can sometimes be occupied by cysteine or leucine residues.<ref name=main />. The typical monoheme cyt ''c'' fold is formed by helices <scene name='Sandbox_Reserved_335/Helices/1'>A, C, and E</scene>. In ''Rm''cyt''c'' there are seven α-helices that are folded around the porphyrin ring, all connected by random coils.<ref name=main /> | ||
In ''Rm''cyt''c'', the porphyrin ring is axially coordinated by <scene name='Sandbox_Reserved_335/Axial/ | In ''Rm''cyt''c'', the porphyrin ring is axially coordinated by <scene name='Sandbox_Reserved_335/Axial/2'>His49 and Met100</scene> | ||
Monoheme cytochromes ''c'' are involved in electron transport chains in both prokaryotes and eukaryotic mitochondria.<ref name=main /> They mediate the transfer of electrons mainly from the ''bc''<sub>1</sub> complexes, or their analogs, in the [http://en.wikipedia.org/wiki/Electron_transport_chain electron transport chain] to heme-copper oxygen reductases (HCOs) during [http://en.wikipedia.org/wiki/Oxidative_phosphorylation oxidative phosphorylation]. Heme ''c'' containing domains are often found fused to other protein domains such as these HCOs, including the ''caa''<sub>3</sub> oxygen reductases<ref name=main /><ref>PMID:14691678</ref>; these enzymes are membrane-bound and catalyze the reduction of O<sub>2</sub> to water.<ref>PMID:11334784</ref> In addition to being involved in the electron transport systems in oxidative phosphorylation, monoheme cyt ''c'' has also been seen to participate in the electron transport chain of [http://en.wikipedia.org/wiki/Photosynthesis photosynthesis].<ref name=main /> | Monoheme cytochromes ''c'' are involved in electron transport chains in both prokaryotes and eukaryotic mitochondria.<ref name=main /> They mediate the transfer of electrons mainly from the ''bc''<sub>1</sub> complexes, or their analogs, in the [http://en.wikipedia.org/wiki/Electron_transport_chain electron transport chain] to heme-copper oxygen reductases (HCOs) during [http://en.wikipedia.org/wiki/Oxidative_phosphorylation oxidative phosphorylation]. Heme ''c'' containing domains are often found fused to other protein domains such as these HCOs, including the ''caa''<sub>3</sub> oxygen reductases<ref name=main /><ref>PMID:14691678</ref>; these enzymes are membrane-bound and catalyze the reduction of O<sub>2</sub> to water.<ref>PMID:11334784</ref> In addition to being involved in the electron transport systems in oxidative phosphorylation, monoheme cyt ''c'' has also been seen to participate in the electron transport chain of [http://en.wikipedia.org/wiki/Photosynthesis photosynthesis].<ref name=main /> | ||
