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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.
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 ...
The iron sulfur proteins contain iron–sulfur clusters, some with elaborate structures, that feature iron and sulfide centers. One broad biosynthetic task is producing sulfide (S 2-), which requires various families of enzymes. Another broad task is affixing the sulfide to iron, which is achieved on scaffolds, which are nonfunctional.
In 1979, Trumpower's team isolated the "oxidation factor" from bovine mitochondria and showed it was a reconstitutively-active form of the Rieske iron-sulfur protein. [2] It is a unique [2Fe-2S] cluster in that one of the two Fe atoms is coordinated by two histidine residues rather than two cysteine residues.
They participate in electron-transfer sequences. The core structure for the [Fe 4 S 4] cluster is a cube with alternating Fe and S vertices. These clusters exist in two oxidation states with a small structural change. Two families of [Fe 4 S 4] clusters are known: the ferredoxin (Fd) family and the high-potential iron–suflur protein (HiPIP ...
The high reduction potential of the N2 cluster and the relative proximity of the other clusters in the chain enable efficient electron transfer over long distance in the protein (with transfer rates from NADH to N2 iron-sulfur cluster of about 100 μs). [12] [13] The equilibrium dynamics of Complex I are primarily driven by the quinone redox cycle.
Electrons from FADH 2 are transferred to the SDHB subunit iron clusters [2Fe-2S],[4Fe-4S],[3Fe-4S] and tunnel along the [Fe-S] relay until they reach the [3Fe-4S] iron sulfur cluster. The electrons are then transferred to an awaiting ubiquinone molecule at the Q pool active site in the SDHC/SDHD dimer.
Ferredoxins (from Latin ferrum: iron + redox, often abbreviated "fd") are iron–sulfur proteins that mediate electron transfer in a range of metabolic reactions. The term "ferredoxin" was coined by D.C. Wharton of the DuPont Co. and applied to the "iron protein" first purified in 1962 by Mortenson, Valentine, and Carnahan from the anaerobic bacterium Clostridium pasteurianum.