鉄‐硫黄タンパク

WordNet

press and smooth with a heated iron; "press your shirts"; "she stood there ironing" (同)iron_out, press
a heavy ductile magnetic metallic element; is silver-white in pure form but readily rusts; used in construction and tools and armament; plays a role in the transport of oxygen by the blood (同)Fe, atomic number 26
implement used to brand live stock (同)branding iron
home appliance consisting of a flat metal base that is heated and used to smooth cloth (同)smoothing iron
a golf club that has a relatively narrow metal head
any of a large group of nitrogenous organic compounds that are essential constituents of living cells; consist of polymers of amino acids; essential in the diet of animals for growth and for repair of tissues; can be obtained from meat and eggs and milk and legumes; "a diet high in protein"
garments (clothes or linens) that are to be (or have been) ironed; "there was a basketful of ironing to do"
the work of using heat to smooth washed clothes in order to remove any wrinkles
an abundant tasteless odorless multivalent nonmetallic element; best known in yellow crystals; occurs in many sulphide and sulphate minerals and even in native form (especially in volcanic regions) (同)S, sulphur, atomic number 16
(of linens or clothes) smoothed with a hot iron

PrepTutorEJDIC

〈U〉『鉄』 / 〈U〉鉄のように堅い(強い,冷たい)こと / 〈C〉鉄製の器具 / 〈C〉[電気]『アイロン』 / 〈C〉アイアン(球を打つ部分が金属のゴルフクラブ) / 〈C〉《複数形で》手かせ,足かせ / 《名詞の前にのみ用いて》『鉄の』,鉄製の / 鉄のように堅い(強い,冷たい) / …‘に'アイロンをかける / 〈人が〉アイロンをかける
蛋白(たんばく)質
アイロンかけ / アイロンかけをした(をする)衣類

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/02/21 03:47:38」(JST)

wiki en

Iron-sulfur proteins are proteins characterized by the presence of iron-sulfur clusters containing sulfide-linked di-, tri-, and tetrairon centers in variable oxidation states. Iron-sulfur clusters are found in a variety of metalloproteins, such as the ferredoxins, as well as NADH dehydrogenase, hydrogenases, Coenzyme Q - cytochrome c reductase, Succinate - coenzyme Q reductase and nitrogenase.^[1] Iron-sulfur clusters are best known for their role in the oxidation-reduction reactions of mitochondrial electron transport. Both Complex I and Complex II of oxidative phosphorylation have multiple Fe-S clusters. They have many other functions including catalysis as illustrated by aconitase, generation of radicals as illustrated by SAM-dependent enzymes, and as sulfur donors in the biosynthesis of lipoic acid and biotin. Additionally some Fe-S proteins regulate gene expression. Fe-S proteins are vulnerable to attack by biogenic nitric oxide.

The prevalence of these proteins on the metabolic pathways of most organisms leads some scientists to theorize that iron-sulfur compounds had a significant role in the origin of life in the Iron-sulfur world theory.

Structural motifs

In almost all Fe-S proteins, the Fe centers are tetrahedral and the terminal ligands are thiolato sulfur centers from cysteinyl residues. The sulfide groups are either two- or three-coordinated. Three distinct kinds of Fe-S clusters with these features are most common.

2Fe-2S clusters

The simplest polymetallic system, the [Fe₂S₂] cluster, is constituted by two iron ions bridged by two sulfide ions and coordinated by four cysteinyl ligands (in Fe₂S₂ ferredoxins) or by two cysteines and two histidines (in Rieske proteins). The oxidized proteins contain two Fe³⁺ ions, whereas the reduced proteins contain one Fe³⁺ and one Fe²⁺ ion. These species exist in two oxidation states, (Fe^III)₂ and Fe^IIIFe^II.

4Fe-4S clusters

A common motif features a four iron ions and four sulfide ions placed at the vertices of a cubane-type structure. The Fe centers are typically further coordinated by cysteinyl ligands. The [Fe₄S₄] electron-transfer proteins ([Fe₄S₄] ferredoxins) may be further subdivided into low-potential (bacterial-type) and high-potential (HiPIP) ferredoxins. Low- and high-potential ferredoxins are related by the following redox scheme:

In HiPIP, the cluster shuttles between [2Fe³⁺, 2Fe²⁺] (Fe₄S₄²⁺) and [3Fe³⁺, Fe²⁺] (Fe₄S₄³⁺). The potentials for this redox couple range from 0.4 to 0.1 V. In the bacterial ferredoxins, the pair of oxidation states are [Fe³⁺, 3Fe²⁺] (Fe₄S₄⁺) and [2Fe³⁺, 2Fe²⁺] (Fe₄S₄²⁺). The potentials for this redox couple range from -0.3 to -0.7 V. The two families of 4Fe-4S clusters share the Fe₄S₄²⁺ oxidation state. The difference in the redox couples is attributed to the degree of hydrogen bonding, which strongly modifies the basicity of the cysteinyl thiolate ligands^{[citation needed]}. A further redox couple, which is still more reducing than the bacterial ferredoxins is implicated in the nitrogenase.

Some 4Fe-4S clusters bind substrates and are thus classified as enzyme cofactors. In aconitase, the Fe-S cluster binds aconitate at the one Fe centre that lacks a thiolate ligand. The cluster does not undergo redox, but serves as a Lewis acid catalyst to convert aconitate to isocitrate. In radical SAM enzymes, the cluster binds and reduces S-adenosylmethionine to generate a radical, which is involved in many biosyntheses.^[2]

3Fe-4S clusters

Proteins are also known to contain [Fe₃S₄] centres, which feature one iron less than the more common [Fe₄S₄] cores. Three sulfide ions bridge two iron ions each, while the fourth sulfide bridges three iron ions. Their formal oxidation states may vary from [Fe₃S₄]⁺ (all-Fe³⁺ form) to [Fe₃S₄]²⁻ (all-Fe²⁺ form). In a number of iron-sulfur proteins, the [Fe₄S₄] cluster can be reversibly converted by oxidation and loss of one iron ion to a [Fe₃S₄] cluster. E.g., the inactive form of aconitase possesses an [Fe₃S₄] and is activated by addition of Fe²⁺ and reductant.

Other Fe-S clusters

More complex polymetallic systems are common. Examples include both the 8Fe and the 7Fe clusters in nitrogenase. Carbon monooxide dehydrogenase and the [FeFe]-hydrogenase also feature unusual Fe-S clusters. A special 6 cysteine-coordinated [Fe₄S₃] cluster was found in oxygen-tolerant membrane-bound [NiFe] hydrogenases.^[3]^[4]

Structure of the FeMoco cluster in nitrogenase. The cluster is linked to the protein by the amino acid residues cysteine and histidine.

Biosynthesis

The biosynthesis of the Fe-S clusters has been well studied.^[5]^[6]^[7] The biogenesis of iron sulfur clusters has been studied most extensively in the bacteria E. coli and A. vinelandii and yeast S. cerevisiae. At least three different biosynthetic systems have been identified so far, namely nif, suf, and isc systems, which were first identified in bacteria. The nif system is responsible for the clusters in the enzyme nitrogenase. The suf and isc systems are more general. The yeast isc system is the best described. Several proteins constitute the biosynthetic machinery via the isc pathway. The process occurs in two major steps: (1) the Fe/S cluster is assembled on a scaffold protein followed by (2) transfer of the preformed cluster to the recipient proteins. The first step of this process occurs in the cytoplasm of prokaryotic organisms or in the mitochondria of eukaryotic organisms. In the higher organisms the clusters are therefore transported out of the mitochondrion to be incorporated into the extramitochondrial enzymes. These organisms also possess a set of proteins involved in the Fe/S clusters transport and incorporation processes that are not homologous to proteins found in prokaryotic systems.

Synthetic analogues

Synthetic analogues of the naturally occurring Fe-S clusters were first reported by Holm and coworkers.^[8] Treatment of iron salts with a mixture of thiolates and sulfide affords derivatives such as (Et₄N)₂Fe₄S₄(SCH₂Ph)₄].

Notes

^ S. J. Lippard, J. M. Berg “Principles of Bioinorganic Chemistry” University Science Books: Mill Valley, CA; 1994. ISBN 0-935702-73-3.
^ Susan C. Wang and Perry A. Frey (2007). "S-adenosylmethionine as an oxidant: the radical SAM superfamily". Trends in Biochemical Sciences 32 (3): 101–10. doi:10.1016/j.tibs.2007.01.002. PMID 17291766.
^ Fritsch, J; Scheerer, P; Frielingsdorf, S; Kroschinsky, S; Friedrich, B; Lenz, O; Spahn, CMT (2011-10-16). "The crystal structure of an oxygen-tolerant hydrogenase uncovers a novel iron-sulphur centre". Nature 479 (7372): 249–252. doi:10.1038/nature10505.
^ Shomura, Y; Yoon, KS; Nishihara, H; Higuchi, Y (2011-10-16). "Structural basis for a [4Fe-3S] cluster in the oxygen-tolerant membrane-bound [NiFe]-hydrogenase". Nature 479 (7372): 253–256. doi:10.1038/nature10504.
^ Johnson D, Dean DR, Smith AD, Johnson MK (2005). "Structure, function and formation of biological iron–sulfur clusters". Annual Review of Biochemistry 74 (1): 247–281. doi:10.1146/annurev.biochem.74.082803.133518. PMID 15952888.
^ Johnson, M.K. and Smith, A.D. (2005) Iron–sulfur proteins in: Encyclopedia of Inorganic Chemistry (King, R.B., Ed.), 2nd edn, John Wiley & Sons, Chichester.
^ Lill R, Mühlenhoff U (2005). "Iron–sulfur-protein biogenesis in eukaryotes". Trends in Biochemical Sciences 30 (3): 133–141. doi:10.1016/j.tibs.2005.01.006. PMID 15752985.
^ T. Herskovitz, B. A. Averill, R. H. Holm, J. A. Ibers, W. D. Phillips and J. F. Weiher (1972). "Structure and Properties of a Synthetic Analogue of Bacterial Iron-Sulfur Proteins". Proceedings of the National Academy of Sciences 69 (9): 2437–2441. doi:10.1073/pnas.69.9.2437. PMC 426959. PMID 4506765.

External links

Iron-Sulfur Proteins at the US National Library of Medicine Medical Subject Headings (MeSH)
Examples of iron-sulfur clusters

UpToDate Contents

全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.

1. 鉄のバランス調節 regulation of iron balance
2. 急性鉄中毒 acute iron poisoning
3. 乳幼児における鉄欠乏：スクリーニング、予防、臨床症状、および診断 iron deficiency in infants and young children screening prevention clinical manifestations and diagnosis
4. 鉄欠乏性貧血を有する成人の治療 treatment of the adult with iron deficiency anemia
5. 幼児および若齢小児における鉄欠乏：治療 iron deficiency in infants and young children treatment

English Journal

Iron-sulfur cluster synthesis, iron homeostasis and oxidative stress in Friedreich ataxia.

Vaubel RA, Isaya G.SourceDepartments of Pediatric & Adolescent Medicine and Biochemistry & Molecular Biology and the Mayo Clinic Children's Center, Mayo Clinic, Rochester, MN 55905, USA.
Molecular and cellular neurosciences.Mol Cell Neurosci.2013 Jul;55:50-61. doi: 10.1016/j.mcn.2012.08.003. Epub 2012 Aug 11.
Friedreich ataxia (FRDA) is an autosomal recessive, multi-systemic degenerative disease that results from reduced synthesis of the mitochondrial protein frataxin. Frataxin has been intensely studied since its deficiency was linked to FRDA in 1996. The defining properties of frataxin - (i) the abilit
PMID 22917739

Ferrous iron oxidation by sulfur-oxidizing Acidithiobacillus ferrooxidans and analysis of the process at the levels of transcription and protein synthesis.

Kucera J, Bouchal P, Lochman J, Potesil D, Janiczek O, Zdrahal Z, Mandl M.SourceDepartment of Biochemistry, Faculty of Science, Masaryk University, Kotlarska 2, 61137, Brno, Czech Republic.
Antonie van Leeuwenhoek.Antonie Van Leeuwenhoek.2013 Apr;103(4):905-19. doi: 10.1007/s10482-012-9872-2. Epub 2013 Jan 5.
In contrast to iron-oxidizing Acidithiobacillus ferrooxidans, A. ferrooxidans from a stationary phase elemental sulfur-oxidizing culture exhibited a lag phase in pyrite oxidation, which is similar to its behaviour during ferrous iron oxidation. The ability of elemental sulfur-oxidizing A. ferrooxida
PMID 23291738

Anaerobic Sulfur Metabolism Coupled to Dissimilatory Iron Reduction in the Extremophile Acidithiobacillus ferrooxidans.

Osorio H, Mangold S, Denis Y, Nancucheo I, Esparza M, Johnson DB, Bonnefoy V, Dopson M, Holmes DS.SourceCenter for Bioinformatics and Genome Biology, Fundacion Ciencia y Vida, Santiago, and Departamento Ciencias Biologicas, Facultad de Ciencias Biologicas, Universidad Andres Bello, Santiago, Chile.
Applied and environmental microbiology.Appl Environ Microbiol.2013 Apr;79(7):2172-81. doi: 10.1128/AEM.03057-12. Epub 2013 Jan 25.
Gene transcription (microarrays) and protein levels (proteomics) were compared in cultures of the acidophilic chemolithotroph Acidithiobacillus ferrooxidans grown on elemental sulfur as the electron donor under aerobic and anaerobic conditions, using either molecular oxygen or ferric iron as the ele
PMID 23354702

Japanese Journal

Mechanistic studies on formation of the dinitrosyl iron complex of the [2Fe-2S] cluster of SoxR protein

Fujikawa Mayu,Kobayashi Kazuo,Kozawa Takahiro
The journal of biochemistry 156(3), 163-172, 2014-09
NAID 40020192577

Studies on hydrogenase

YAGI Tatsuhiko,HIGUCHI Yoshiki
Proceedings of the Japan Academy, Series B 89(1), 16-33, 2013
… The simplest [NiFe]-hydrogenase is a heterodimer, in which the large subunit bears the Ni-Fe center buried deep in the protein, and the small subunit bears iron-sulfur clusters, which mediate electron transfer between the Ni-Fe center and the protein surface. …
NAID 130003365103

Indolepyruvate ferredoxin oxidoreductase : An oxygen-sensitive iron–sulfur enzyme from the hyperthermophilic archaeon Thermococcus profundus

Ozawa Yukiko,Siddiqui Masood Ahmed,Takahashi Yasufumi [他],Urushiyama Akio,Ohmori Daijiro,Yamakura Fumiyuki,Arisaka Fumio,Imai Takeo
Journal of bioscience and bioengineering 114(1), 23-27, 2012-07
Department of Chemistry, Juntendo University
NAID 110009479359