Iron–sulfur cluster

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Structure of [Fe4S4(SMe)4]2−, a synthetic analogue of 4Fe-4S cofactors.[1]

Iron–sulfur clusters are molecular ensembles of iron and sulfide. They are most often discussed in the context of the biological role for iron-sulfur proteins, which are pervasive.[2] Many Fe-S clusters are known in the area of organometallic chemistry and as precursors to synthetic analogues of the biological clusters (see Figure).

Biological Fe-S clusters[edit]

Fe-S clusters can be classified according to their Fe:S stoichiometry [2Fe-2S], [4Fe-3S], [3Fe-4S], and [4Fe-4S].[3]. The [4Fe-S] clusters occur in two forms: normal ferredoxins and high potential iron proteins (HiPIP). Both are cuboidal in shape but differ in terms of the relevant oxidation states. They are found in all forms of life.[4].

The relevant redox couple in all Fe-S proteins is Fe(II)/Fe(III).[5]

Many clusters have been synthesized in the laboratory with the formula [Fe4S4(SR)4]2−, which are known for many R substituents, and with many cations. Variations have been prepared including the incomplete cubanes [Fe3S4(SR)3]3−.[6]

Organometallic clusters[edit]

Organometallic Fe-S clusters include the sulfido carbonyls with the formula Fe2S2(CO)6, H2Fe3S(CO)9, and Fe3S2(CO)9. Compounds are also known that incorporate cyclopentadienyl ligands, such as (C5H5)4Fe4S4.[7]

Figure. Illustrative synthetic Fe-S clusters. From left to right: Fe3S2(CO)9, [Fe3S(CO)9]2−, (C5H5)4Fe4S4, and [Fe4S4Cl4]2−.

Fe-S Clusters in biology[edit]

Iron-sulfur clusters occur in many biological systems, often as components of electron transfer proteins. The ferredoxin proteins are the most common Fe-S clusters in nature. They feature either 2Fe-2S or 4Fe-4S centers. They occur in all branches of life.[8]

The Rieske proteins contain Fe-S clusters that coordinate as a 2Fe-2S structure and can be found in the membrane bound cytochrome bc1 complex III in the mitochondria of animals and bacteria (eukaryotic cells). They are also a part of the proteins of the chloroplast such as the cytochrome b6f complex in photosynthetic organisms. These photosynthetic organisms include plants, cyanobacteria, and green algae (prokaryotic cells). Both are part of the electron transport chain of their respective organisms which is a crucial step in the energy harvesting for many organisms.[9]

In some instances Fe-S clusters are redox-inactive, but are proposed have structural roles. Examples include endonuclease III and MutY.[8][10]

See also[edit]

References[edit]

  1. ^ Axel Kern, Christian Näther, Felix Studt, Felix Tuczek (2004). "Application of a Universal Force Field to Mixed Fe/Mo−S/Se Cubane and Heterocubane Clusters. 1. Substitution of Sulfur by Selenium in the Series [Fe4X4(YCH3)4]2-; X = S/Se and Y = S/Se". Inorg. Chem. 43: 5003–5010. doi:10.1021/ic030347d.
  2. ^ S. J. Lippard, J. M. Berg “Principles of Bioinorganic Chemistry” University Science Books: Mill Valley, CA; 1994. ISBN 0-935702-73-3.
  3. ^ Lill, Roland. "Issue of iron-sulfur protein". Biochim Biophys Acta. Retrieved 2017. Check date values in: |accessdate= (help)
  4. ^ Fisher, N (1998). "Intramolecular electron transfer in [4Fe-4S)]". The EMBO journal: 849-858.
  5. ^ Fisher, N (1998). "Intramolecular electron transfer in [4Fe-4S)]". The EMBO journal: 849-858.
  6. ^ Rao, P. V.; Holm, R. H. (2004). "Synthetic Analogues of the Active Sites of Iron-Sulfur Proteins". Chem. Rev. 104: 527─559. doi:10.1021/Cr020615+.
  7. ^ Ogino, H., Inomata, S., Tobita, H. (1998). "Abiological Iron-Sulfur Clusters". Chem. Rev. 98: 2093. doi:10.1021/cr940081f.
  8. ^ a b Johnson, D. C., Dean, D. R., Smith, A. D., Johnson, M. K. (2005). "Structure, function, and formation of biological iron-sulfur clusters". Annual Review of Biochemistry. 74: 247–281. doi:10.1146/annurev.biochem.74.082803.133518.
  9. ^ BIOLOGICAL INORGANIC CHEMISTRY : structure and reactivity. [S.l.]: UNIVERSITY SCIENCE BOOKS. 2018. ISBN 193878796X. OCLC 1048090793.
  10. ^ Guan, Y.; Manuel, R. C.; Arvai, A. S.; Parikh, S. S.; Mol, C. D.; Miller, J. H.; Lloyd, S.; Tainer, J. A. (1998-12). "MutY catalytic core, mutant and bound adenine structures define specificity for DNA repair enzyme superfamily". Nature Structural Biology. 5 (12): 1058–1064. doi:10.1038/4168. ISSN 1072-8368. PMID 9846876. Check date values in: |date= (help)

External links[edit]