Disease relevance of Suox

• Molecular cloning of rat liver sulfite oxidase. Expression of a eukaryotic Mo-pterin-containing enzyme in Escherichia coli [1].
• Sulfite oxidase (SOX), a heme- and molybdenum containing mitochondrial enzyme, prevents mammalian cells from adverse effects of sulfite toxicity by metabolizing sulfite to sulfate [2].

High impact information on Suox

• Site-directed mutagenesis of recombinant sulfite oxidase: identification of cysteine 207 as a ligand of molybdenum [3].
• Each of the four cysteines in rat sulfite oxidase was altered by site-directed mutagenesis to serine, and the mutant proteins were expressed in Escherichia coli [3].
• The amino acid sequence deduced from the cDNA shows significant similarity to those of sulfite oxidase from chicken liver and nitrate reductases from algal, fungal, and plant sources [1].
• The cDNA encoding sulfite oxidase has been cloned from a rat liver cDNA library [1].
• Oxidation of molybdopterin in sulfite oxidase by ferricyanide. Effect on electron transfer activities [4].

Biological context of Suox

• The amino acid sequences of peptides derived from rat hepatic sulfite oxidase have been determined by a combination of amino acid analysis and Edman degradation of the purified protein [5].
• This included up-regulation of pyruvate dehydrogenase, phenylalanine hydroxylase, and 2-oxoisovalerate dehydrogenase, which are involved in acetyl-CoA production, and down-regulation of sulfite oxidase, which could play a role in triglyceride accumulation [6].
• The properties of sulfite oxidation in perfused rat liver; interaction of sulfite oxidase with the mitochondrial respiratory chain [7].
• In conclusion, sulfite has neurotoxic effects in sulfite oxidase deficient rats, but this effect may not depend on oxidative stress [8].
• Some of these rats were simultaneously exposed either to SO2 by inhalation or to sulfite/bisulfite anions that accumulated systemically from endogenous generation in rats with induced sulfite oxidase deficiency [9].

Anatomical context of Suox

• Rat liver L-glutamate dehydrogenase, malate dehydrogenase, D-beta-hydroxybutyrate dehydrogenase, and sulfite oxidase are each synthesized as larger precursors by cytoplasmic free polysomes [10].
• Sulfite oxidase activity in the intestinal mucosa was only 5% of that seen in liver and did not change in response to dietary protein or methionine [11].
• Loss of sulfite oxidase activity and outer membrane damage in rat hepatic mitochondria during CC14 poisoning [12].
• Evidence for participation of the inner membrane in the import of sulfite oxidase into the intermembrane space of liver mitochondria [13].
• Biosynthesis of sulfite oxidase in rat liver - presence of a large precursor form of the enzyme in cytosol [14].

Associations of Suox with chemical compounds

• Treatment of rat liver sulfite oxidase with trypsin leads to loss of ability to oxidize sulfite in the presence of cytochrome c as electron acceptor [15].
• Tryptic cleavage of rat liver sulfite oxidase. Isolation and characterization of molybdenum and heme domains [15].
• It appears that the tungsten center in sulfite oxidase is incapable of oxidizing sulfite [16].
• The state of reduction of molybdopterin in xanthine oxidase and sulfite oxidase [17].
• The attenuation of the sulfite:cytochrome c activity of sulfite oxidase upon treatment with ferricyanide was demonstrated to be the result of oxidation of the pterin ring of the molybdenum cofactor in the enzyme [4].

Other interactions of Suox

• Studies on the reoxidation of W(V) and reduced heme by O2 and by cytochrome c suggest that the cytochrome b5 of sulfite oxidase is the site of electron transfer to cytochrome c, whereas oxidase activity is the property of the molybdenum center [16].
• The testes of grossly sulfite oxidase-deficient rats were severely atrophied and devoid of spermatogenic cells [18].
• Studies were made of photodamage (photolysis) caused by Rose Bengal + light of peroxisomes, mitochondria, and lysosomes, as well as inhibition of the respective marker enzymes: catalase, sulfite oxidase, and acid phosphatase [19].
• Furthermore, antibodies to 29 kDa outer membrane protein, a component of the import machinery in contact sites for precursors of ornithine aminotransferase and sulfite oxidase, inhibited the integration of porin, suggesting that the 29 kDa protein is involved in the imports of most mitochondrial precursor proteins [20].

Analytical, diagnostic and therapeutic context of Suox

• Gel filtration of the proteolytic products has led to the isolation of two major fragments of dissimilar size derived from sulfite oxidase [15].
• The specificity of the immunoprecipitation of sulfite oxidase nascent peptides was confirmed by examination of the size distribution of immunoprecipitated peptides and by the competition with purified enzyme in the immunoprecipitation [21].

References