Enzyme family
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Sulfite reductases (EC 1.8.99.1 ) are enzymes that participate in sulfur metabolism .[ 2] They catalyze the reduction of sulfite to hydrogen sulfide and water.[ 2] [ 3] Electrons for the reaction are provided by a dissociable molecule of either NADPH , bound flavins , or ferredoxins .[ 4]
SO3 2− (sulfite) + electron donor
⇌
{\displaystyle \rightleftharpoons }
H2 S (hydrogen sulfide) + oxidized donor + 3 H2 O
Sulfite reductases, which belong to the oxidoreductase family, are found in the archaea , bacteria , fungi , and plants .[ 5] [ 6] [ 7] 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.[ 8]
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.
^ PDB : 1AOP ; Crane BR, Siegel LM, Getzoff ED (October 1995). "Sulfite reductase structure at 1.6 A: evolution and catalysis for reduction of inorganic anions". Science . 270 (5233): 59–67. Bibcode :1995Sci...270...59C . doi :10.1126/science.270.5233.59 . PMID 7569952 . S2CID 31246227 .
^ a b Parey K, Warkentin E, Kroneck PM, Ermler U (October 2010). "Reaction cycle of the dissimilatory sulfite reductase from Archaeoglobus fulgidus". Biochemistry . 49 (41): 8912–21. doi :10.1021/bi100781f . PMID 20822098 .
^ Pinto R, Harrison JS, Hsu T, Jacobs WR, Leyh TS (September 2007). "Sulfite reduction in mycobacteria" . Journal of Bacteriology . 189 (18): 6714–22. doi :10.1128/JB.00487-07 . PMC 2045171 . PMID 17644602 .
^ Siegel LM, Murphy MJ, Kamin H (January 1973). "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. doi :10.1016/S0021-9258(19)44469-4 . PMID 4144254 .
^ Brychkova G, Yarmolinsky D, Ventura Y, Sagi M (August 2012). "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. doi :10.1093/pcp/pcs084 . PMID 22685081 .
^ Yarmolinsky D, Brychkova G, Kurmanbayeva A, Bekturova A, Ventura Y, Khozin-Goldberg I, Eppel A, Fluhr R, Sagi M (August 2014). "Impairment in Sulfite Reductase Leads to Early Leaf Senescence in Tomato Plants" . Plant Physiology . 165 (4): 1505–1520. doi :10.1104/pp.114.241356 . PMC 4119034 . PMID 24987017 .
^ Schnell R, Sandalova T, Hellman U, Lindqvist Y, Schneider G (July 2005). "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. doi :10.1074/jbc.M502560200 . PMID 15917234 .
^ Crane BR, Getzoff ED (December 1996). "The relationship between structure and function for the sulfite reductases". Current Opinion in Structural Biology . 6 (6): 744–56. doi :10.1016/S0959-440X(96)80003-0 . PMID 8994874 .