Biotin sulfoxide

The formal transfer of an oxygen atom is one way of describing the function of the Mo site in molybdoenzymes.5 The formation of dinuclear reduction products is a complication that causes difficulty in trying to model the mononuclear site.5,165 This difficulty can be overcome by the use of sterically demanding ligands that prevent the formation of the dinuclear complex,73 79,125 176 177 For example, the cycle shown in Scheme 3 can be effected without dimerization. Further, in this case DMSO and the enzyme substrate biotin sulfoxide, can serve as the oxo donor to form the Movl dioxo complex during the catalytic cycle.79,177 The Movl complex involved is discussed structurally above (Figure 7). 

Alicyclic thioether sulfoxidation is also a route of biotransformation in bacteria and plants. For example, biotin (95), the most important naturally occurring tetrahydrothiophene derivative so far recognized, has been found to exist in bacteria as biotin sulfoxide (96)... 

A molybdenum cofactor has been isolated from Proteus mirabilis 047, and has a molecular weight greater than 1000. The molybdoenzymes of E. coli, in addition to the formate dehydrogenases described above and the nitrate reductase (Section 62.1.9.6), also include the membrane-bound trimethylamine oxidase1044 and the soluble biotin sulfoxide reductase.1045... 

Aldehyde ferredoxin oxidoreductase Benzene-1,2-dithiolate Biotin sulfoxide reductase Density functional theory... 

Biotin deficiency in experimental animals is teratogenic, and a number of the resultant birth defects resemble human birth defects. Up to half of pregnant women have elevated excretion of 3-hydroxy-isovaleric acid (Section 11.4), which responds to supplements of biotin, in the first trimester, suggesting that marginal stams may be common in early pregnancy and may be a factor in the etiology of some birth defects. This may be the result of increased catabolism of biotin as a result of steroid induction of biotin catabolic enzymes there is increased excretion of bisnorbiotin and biotin sulfoxide (Zempleni and Mock, 2000a Mock et al., 2002). 

Figure 11.2. Biotin metabolites. Relative molecular masses (Mr) biotin, 244.3 biotin sulfoxide, 260.3 biotin sulfone, 276.3 bisnorbiotin, 212.3 tetranorbiotin, 180.3 and bisnorbiotin sulfoxide, 228.3.

Pierson, D. E., and Campbell, A., 1990, Cloning and nucleotide sequence of bisC, the structural gene for biotin sulfoxide reductase in Escherichia coli, J. Bacterial. 172 219492198. 

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