Sulfite dehydrogenase

SULFITE DEHYDROGENASE SULFITE OXIDASE SULFITE REDUCTASE SULFONIUM SALTS SULFOTRANSFERASES SULFUR-35 f=S)... 

Sulfite Sulfite oxidase, sulfite dehydrogenase Wines Antioxidant agent... 

Wodara, C., Bardischewsky, F., and Friedrich, C. G., 1997, Cloning and characterization of sulfite dehydrogenase, two c-type cytochromes, and a flavoprotein of Paracoccus denitri-ficans GB17 essential role of sulfite dehydrogenase in lithotrophic sulfur oxidation. J. Bacterial. 179 501495023. 

Sulfite dehydrogenase Starkeya novella afi, 50 Mo02(SCys)(MPT) heme c S03 " — S04 " ... 

Similar enzymes are known to occur in Paracoccus (Thiobacillus) versutus (Lu and Kelly, 1984a,b) and T. thioparus (Lyric and Suzuki, 1970b). The P. versutus enzyme has a molecular mass of 44 kDa and contains cytochrome c-551. The T. thioparus enzyme has one atom each of nonheme iron and molybdenum (Kessler and Rajagopalan, 1972). A membrane-bound type sulfite dehydrogenase has been obtained from Thiobacillus (Acidithiobacillus) thiooxidans JCM 7814. The enzyme has the molecular mass of 400 kDa and catalyzes the reduction of horse ferricytochrome c with sulfite (Nakamura et al., 1995, 2001). Also from Paracoccus (Thio-sphaera) pantotrophus GB17, sulfite dehydrogenase has been obtained. Its molecular mass is 190 kDa (2 x 47 kDa + 2 x 50 kDa) and it has 4 heme C molecules and 1-2 atoms of molybdenum (Quentmeier et al., 2000). Furthermore,... 

Nakamura K, Yoshikawa H, Okubo S, Kurosawa H, Amano Y (1995) Purification and properties of membrane-bound sulfite dehydrogenase from Thiobacillus thiooxidans JCM 7814. Biosci Biotechnol Biochem 59 11-15... 

Quentmeier A, Kraft R, Kostka S, Klockenkamper R, Friedrich CG (2000) Characterization of a new type of sulfite dehydrogenase from Paracoccus pantotrophus GB17. Arch Microbiol 175 117-125... 

Enzymes of the sulfite oxidase family coordinate a single equivalent of the pterin cofactor with an MPT-Mo 02 core in its oxidized state (54, Figure 16), and usually an additional cysteine ligand, which is provided by the polypeptide. Members of this family catalyze the transfer of an oxygen atom either to or from the substrate. Among the members of this family are sulfite oxidase, sulfite dehydrogenase, assimilatory nitrate reductases, and the YedY protein, the catalytic subunit of a sulfite oxidase homologue in E. coli So far, all members of this family contain the MPT-form of Moco without an additional dinucleotide. 

The active site geometries (Figure 2.14) of the sulfite oxidizing enzymes are quite similar and examples of high-resolution X-ray crystal structures can be found for the S. novella sulfite dehydrogenase (bacterial)/ A. thaliana sulfite oxidase (plant)/ bacterial YedY/ and vertebrate sulfite oxidase. ... 

The sulfite oxidase enzymes are widespread in Nature, and are found in plants, bacteria (the sulfite dehydrogenases) and in birds and mammals. In addition, this family also includes the assimilatory plant nitrate reductases, which have essentially similar molybdenum coordination and differ structurally in lacking an active site arginine that is present in sulfite oxidase, and in showing somewhat different active site structures on turnover. We will focus here on the animal sulfite oxidase enzymes, of which chicken and human are the best studied. In animals the enzyme is responsible for the physiologically essential oxidation of sulfite to sulfate. It is a dimer of 52 kDa subunits and resides in the mitochondrial inner-membrane space. Each monomer contains Mo associated with one molybdopterin, plus a cytochrome heme. The enzymes catalyze the following reaction, which occurs at the Mo site which is reduced from Mo(vi) to Mo(iv) in the process ... 

The sulfite-oxidizing enzymes can be separated into two elasses, the eukaryotic sulfite oxidases (SO), found in animals and plants, and the sulfite dehydrogenases (SDH), found in bacteria. Plant [Arabidopsis thaliana) SO is the simplest Mo enzyme from this family bearing only a Mo eofaetor. This enzyme is found in peroxisomes and donates electrons directly to dioxygen. Vertebrate SO is a mitochondrial enzyme also containing a heme cofactor, which acts as an electron relay between the Mo active site and its physiological electron acceptor cytochrome c. The two most studied vertebrate sulfite oxidizing enzymes are chicken SO and human SO. ... 

Crystal structure of S. novella sulfite dehydrogenase showing the proximity of the Mo active site and the heme cofactor (PDB 2BLF). 

Sulfite oxidase (sulfite dehydrogenase) (EC 1.8.3.1). Urinary excretion of S-sulfo-L-cysteine, sulfite and thiosulfate, and virtual absence of urinary sulfate. Progressive neurological abnormalities, mental retardation, lens dislocatioiL Treatment with diet low in sulfur amino acids. Death in postnatal period possi-... 

Beef heart preparations allow sulfite to accumulate. In bacterial and liver systems sulfate is the product. (8-Sulfonylpyruvate has been found to be inert in both systems, indicating that the sulfate is formed by oxidation of inorganic sulfite. A partially purified sulfite dehydrogenase has been obtained from liver. This enzyme catalyzes the reduction of methylene blue by sulfite. Similar activities have been found in some bacteria. 

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