Escherichia coli sulfite reductase

Although electron transfers in biological systems are generally expected to be non-adiabatic, it is possible for some intramolecular transfers to be close to the adiabatic limit, particularly in proteins where several redox centers are held in a very compact arrangement. This situation is found for example in cytochromes C3 of sulfate-reducing bacteria which contain four hemes in a 13 kDa molecule [10, 11], or in Escherichia coli sulfite reductase where the distance between the siroheme iron and the closest iron of a 4Fe-4S cluster is only 4.4 A [12]. It is interesting to note that a very fast intramolecular transfer rate of about 10 s was inferred from resonance Raman experiments performed in Desulfovibrio vulgaris Miyazaki cytochrome Cj [13]. 

Belinsky MI. 1996. Hyperfine evidence of strong double exchange in multimetallic [Fe4S4]-Fe) active center of Escherichia coli sulfite reductase. J Biol Inorg Chem 1 186-8. 

McRee, D. E., Richardson, D. C., Richardson, J. S., and Siegel, L. M. (1986). The heme and Fe4S4 cluster in the crystallographic structure of Escherichia coli sulfite reductase. J. Biol. Chem. 261, 10277-10281. 

Christner JA, Janick PA et al (1983) Mossbauer studies of Escherichia coli sulfite reductase complexes with carbon monoxide and cyanide. Exchange coupling and intrinsic properties of the [4Fe-4S] cluster. J Biol Chem 258 11157-11164... 

In 1973, the first naturally occurring isobacteriochlorin, iron-containing siroheme, was isolated1 from a sulfite reductase of Escherichia coli. Later it was also discovered in sulfite and nitrite reductases of numerous bacteria and plants.2 Iron-free sirohydrochlorins (also called factor II) were discovered in vitamin B12 producing bacteria.3-4 Together with factor III. a sirohydrochlorin methylated in the 20-position, the reduced forms of factor II and factor III were identified as biosynthetic intermediates in the biosynthesis of vitamin B12.5... 

Eschenbrenner M, E Coves, M Fontecave (1995) The flavin reductase activity of the flavoprotein component of sulfite reductase bom Escherichia coli. J Biol Chem 270 20550-20555. 

There are a number of more complex Fe-S clusters whose structures are known and some of them are illustrated in Figure 2.10 (Beinert, 2000 Holm et al., 1996). In the sulfite reductase of Escherichia coli a 4Fe-4S cluster is linked via a cysteine to the... 

Figure 2.10 Schematic structures of (a) sulfite reductase of Escherichia coli in which a 4Fe-4S cluster is linked via a cysteine to the iron in a sirohaem (b) P cluster of nitrogenase (c) FeMoCo cluster of nitrogenase (d) the binuclear site in Desulforibrio gigas hydrogenase.

Crane BR, Siegel LM, Getzoff ED. Probing the catalytic mechanism of sulfite reductase by X-ray crystallography Structures of the Escherichia coli hemoprotein in complex with substrates, inhibitors, intermediates, and products. Biochemistry 1997 36 12120-37. 

Ostrowski, J., M.J. Barber, D.C. Rueger, B.E. Miller, L.M. Siegel, and N.M. Kredich (1989). Characterization of the flavoprotein moieties of NADPH-sulfite reductase from Salmonella typhimurium and Escherichia coli. Physicochemical and catalytic properties, amino acid sequence deduced from DNA sequence of cysJ, and comparison with NADPH-cytochrome P-450 reductase. J. Biol. Chem. 264, 15796-15808. 

In 1973, the iron complex of sirohydrochlorin (92) was isolated from Escherichia coli, where it serves as a cofactor for sulfite reductase, Siroheme (93) also catalyzes the six electron reduction of nitrite to ammonia in nitrite reductase systems. Perhaps most remarkably of all, not only has sirohydrochlorin (92)... 

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