Sulfite metabolism

Molybdenum deficiency is manifest by alterations in the uric acid and sulfite metabolism, often noted by the development of mouth and gum abnormalities, hypouricemia, hyperoxypurinemia, and eventually coma. 

C. uti/is yeast is produced by either fed-batch or continuous processes. Aerated-agitated fermentors range up to 300 m total capacity and ate operated in the same manner as described for S. cerevisiae (2,5). C. utilis is capable of metabolizing both hexose and pentose sugars. Consequendy, papermiU wastes such as sulfite waste Hquot that contain these sugars often ate used as substrates. 

IGTS8 or simply IGTS8. The metabolic pathway in Rhodococcus sp. IGTS8 was delineated in the early 1990s [62], The pathway consists of four enzymes. DBT is converted to 2-hydroxybiphenyl (HBP) and sulfite via a 4-step pathway and the following intermediates DBT sulfoxide (dibenzothiophene-5-oxide, DBTO), DBT sulfone (dibenzothiophene-5,5-dioxide, DBT02) and hydroxyphenyl benzene sulfonate (phenol-phenyl sulfinate, HBPSi). 

Microsomes are capable of oxidizing not only organic substrates but also inorganic ones. An interesting example is the metabolism of bisulfite (aqueous sulfur dioxide) in microsomes. Although mitochondrial sulfite oxidase is responsible for the in vivo oxidation of bisulfite by a two-electron mechanism, cytochrome P-450 is also able to reduce bisulfite to the sulfur dioxide radical anion [56] ... 

Marques, I.A. and L.E. Anderson. 1986. Effects of arsenite, sulfite, and sulfate on photosynthetic carbon metabolism in isolated pea (Pisum sativum L., cv Little Marvel) chloroplasts. Plant Physiol. 82 488-493. 

The ability to catalyse the evolution or oxidation of H2 may have been exploited by the earliest life forms as H2 would have been present in the early prebiotic environments. The origins of the proton-dependent chemiosmotic mechanism for ATP synthesis may also reflect the formation of proton gradients created by hydrogenases on either side of the cytoplasmic membrane. In addition, it has been speculated that the coupling of H2 and S metabolisms was also of fundamental importance in the origin of life. These two processes seem intimately coupled in the bifunctional sulfhydrogenase found in Pyrococcus furiosus (a combination of subunits for hydrogenase and sulfite reductase) which can dispose of excess reductant either by the reduction of protons to H2 or S° to H2S (Ma et al. 1993 Pedroni et al. 1995). 

Aranda, A. Jimenez-Marti, E. Orozco, H. Matallana, E. del Olmo, M. Sulfur and Adenine Metabolisms Are Linked, and Both Modulate Sulfite Resistance in Wine Yeast. J. Agric. Food Chem. 2006, 54, 5839-5846. 

Johnson JL, Duran M (2001) Molybdenum cofactor deficiency and isolated sulfite oxidase deficiency. In Scriver CR, Beaudet AL, Sly WS, Valle D (eds) The Metabolic and Molecular Bases of Inherited Disease, 8th edn. McGraw-Hill, New York, NY, pp 3163-3177... 

The first hint of an essential role of molybdenum in metabolism came from the discovery that animals raised on a diet deficient in molybdenum had decreased liver xanthine oxidase activity. There is no evidence that xanthine oxidase is essential for all life, but a human genetic deficiency of sulfite oxidase or of its molybdopterin coenzyme can be lethal.646,646a,b The conversion of molybdate into the molybdopterin cofactor in E. coli depends upon at least five genes.677 In Drosophila the addition of the cyanolyzable sulfur (Eq. 16-64) is the final step in formation of xanthine dehydrogenase.678 It is of interest that sulfur (S°) can be transferred from rhodanese (see Eq. 24-45), or from a related mercaptopyruvate sulfurtransferase679 into the desulfo form of xanthine oxidase to generate an active enzyme.680... 

Cysteine not only is an essential constituent of proteins but also lies on the major route of incorporation of inorganic sulfur into organic compounds.443 Autotrophic organisms carry out the stepwise reduction of sulfate to sulfite and sulfide (H2S). These reduced sulfur compounds are the ones that are incorporated into organic substances. Animals make use of the organic sulfur compounds formed by the autotrophs and have an active oxidative metabolism by which the compounds can be decomposed and the sulfur reoxidized to sulfate. Several aspects of cysteine metabolism are summarized in Fig. 24-25. Some of the chemistry of inorganic sulfur metabolism has been discussed in earlier chapters. Sulfate is reduced to H2S by sulfate-reducing bacteria (Chapter 18). The initial step in assimilative sulfate reduction, used by... 

Another route of metabolism for cysteine sulfinic acid is transamination to 3-sulfinylpyruvate, a compound that undergoes ready loss of S02 in a reaction analogous to the decarboxylation of oxaloacetate (reaction o, Fig. 24-25). This probably represents one of the major routes by which sulfur is removed from organic compounds in the animal body. However, before being excreted the sulfite must be oxidized to sulfate by the Mo-containing sulfite oxidase. The essentiality of sulfite oxidase is evidenced by the severe neurological defect observed in its absence (Chapter 16). 

Molybdenum deliciency in humans results in deranged metabolism of sulfur and purines und symptoms ol mental disturbances. Toxic levels produce elevated uric acid in blood, gout, anemia, and growth depression. Faulty utilization results in sulfite oxidase deliciency. a lethal inhom error. 

Molybdenum 10 mg 150- 500 pig In metalloenzymes xanthine, aldehyde, sulfite oxidases Faulty metabolism of xanthine, sulfur Gout-like syndrome in parts of Soviet Union... 

Figure 5. The metabolism of 3S-S radiolabeled sulfide by boiled and intact isolated Solemya reidi mitochondria. Time zero is prior to addition of mitochondria. When mitochondria are added there is a rapid decrease in sulfide concentration caused partially by dilution of the total volume and partially by binding of sulfide to protein. In the boiled preparation there is very little oxidation of sulfide and no appearance of oxidized products. In the healthy mitochondria the sulfide is rapidly oxidized to thiosulfate. Sulfite and sulfate did not appear as oxidation products. The health of the isolated mitochondria was monitored by oxygen consumption rate in the chamber with succinate as substrate and by the ability to inhibit succinate stimulated respiration with respiratory inhibitors such as cyanide. Error bars represent plus and minus one standard deviation of the mean of three runs.

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