Sulfite reductase explained

sulfite reductase
Ec Number:	1.8.99.1
Cas Number:	37256-51-2
Go Code:	0016002
Pdb:	1AOP, 8GEP

Sulfite reductases are enzymes that participate in sulfur metabolism.^[1] They catalyze the reduction of sulfite to hydrogen sulfide and water.^{[1] [2]} Electrons for the reaction are provided by a dissociable molecule of either NADPH, bound flavins, or ferredoxins.^[3]

SO₃²⁻ (sulfite) + electron donor

\rightleftharpoons H₂S (hydrogen sulfide) + oxidized donor + 3 H₂O

Sulfite reductases, which belong to the oxidoreductase family, are found in the archaea, bacteria, fungi, and plants.^{[4] [5] [6]} They are grouped as either the assimilatory or the dissimilatory sulfite reductases depending on their function, their spectroscopic properties, and their catalytic properties. This enzyme participates in selenoamino acid metabolism and sulfur assimilation. It employs two covalently coupled cofactors - an iron sulfur cluster and a siroheme - which the deliver electrons to the substrate via this coupling.^[7]

The systematic name of this enzyme class is hydrogen-sulfide:acceptor oxidoreductase. Other names in common use include assimilatory sulfite reductase, assimilatory-type sulfite reductase, and hydrogen-sulfide:(acceptor) oxidoreductase.

Further reading

• Asada K . Purification and properties of a sulfite reductase from leaf tissue . The Journal of Biological Chemistry . 242 . 16 . 3646–54 . August 1967 . 10.1016/S0021-9258(18)95858-8 . 6038492 . free .
• Asada K, Tamura G, Bandurski RS . Methyl viologen-linked sulfite reductase from spinach leaves . The Journal of Biological Chemistry . 244 . 18 . 4904–15 . September 1969 . 10.1016/S0021-9258(18)94289-4 . 5824566 . free .
• Yoshimoto A, Nakamura T, Sato R . Isolation from Aspergillus nidulans, of a protein catalyzing the reduction of sulfite by reduced viologen dyes . Journal of Biochemistry . 62 . 6 . 756–66 . December 1967 . 5589532 . 10.1093/oxfordjournals.jbchem.a128732.

Notes and References

1. Parey K, Warkentin E, Kroneck PM, Ermler U . Reaction cycle of the dissimilatory sulfite reductase from Archaeoglobus fulgidus . Biochemistry . 49 . 41 . 8912–21 . October 2010 . 20822098 . 10.1021/bi100781f .
2. Pinto R, Harrison JS, Hsu T, Jacobs WR, Leyh TS . Sulfite reduction in mycobacteria . Journal of Bacteriology . 189 . 18 . 6714–22 . September 2007 . 17644602 . 2045171 . 10.1128/JB.00487-07 .
3. Siegel LM, Murphy MJ, Kamin H . Reduced nicotinamide adenine dinucleotide phosphate-sulfite reductase of enterobacteria. I. The Escherichia coli hemoflavoprotein: molecular parameters and prosthetic groups . The Journal of Biological Chemistry . 248 . 1 . 251–64 . January 1973 . 10.1016/S0021-9258(19)44469-4 . 4144254 . free .
4. Brychkova G, Yarmolinsky D, Ventura Y, Sagi M . A novel in-gel assay and an improved kinetic assay for determining in vitro sulfite reductase activity in plants . Plant & Cell Physiology . 53 . 8 . 1507–16 . August 2012 . 22685081 . 10.1093/pcp/pcs084 . free .
5. Yarmolinsky D, Brychkova G, Kurmanbayeva A, Bekturova A, Ventura Y, Khozin-Goldberg I, Eppel A, Fluhr R, Sagi M . Impairment in Sulfite Reductase Leads to Early Leaf Senescence in Tomato Plants . Plant Physiology . 165 . 4 . 1505–1520 . August 2014 . 24987017 . 4119034 . 10.1104/pp.114.241356 .
6. Schnell R, Sandalova T, Hellman U, Lindqvist Y, Schneider G . Siroheme- and [Fe4-S4]-dependent NirA from Mycobacterium tuberculosis is a sulfite reductase with a covalent Cys-Tyr bond in the active site . The Journal of Biological Chemistry . 280 . 29 . 27319–28 . July 2005 . 15917234 . 10.1074/jbc.M502560200 . free .
7. Crane BR, Getzoff ED . The relationship between structure and function for the sulfite reductases . Current Opinion in Structural Biology . 6 . 6 . 744–56 . December 1996 . 8994874 . 10.1016/S0959-440X(96)80003-0 .