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Flavins sulfides

Walsh and coworkers oxidized ethyl p-tolyl sulfide on an analytical scale to the S-sulfoxide of 64% enantiomeric purity using a bacterial flavoenzyme cyclohexanone monooxygenase derived from Adnetobacter . Using a flavin adenine dinucleotide containing monooxygenase purified from hog liver microsomes yielded the R-sulfoxide of 90% enantiomeric purity. HPLC on a column containing a 3,5-dinitrobenzoyl-D-phenylglycine chiral stationary phase was used to determine the optical purity of the sulfoxides. [Pg.78]

A class of enzymes capable of removing sulfur from alkane sulfonates exists, which may have relevance in microbial desulfurization of alkyl sulfides. A gene cluster ssuEADCB was identified in E. coli. The enzyme SsuD was capable of conversion of pentane sulfonic acid to pentaldehyde and sulfite. It was reported to be capable of conversion of alkyl sulfonates from C2 to CIO, as well as substituted ethanesulfonates and sulfonated buffers. The SsuE was a flavin-reducing enzyme that provided FMNH2 to the SsuD. [Pg.103]

A still more complicated reaction is the chemiluminescent oxidation of sodium hydrogen sulfide, cysteine, and gluthathione by oxygen in the presence of heavy metal catalysts, especially copper ions 60>. When copper is used in the form of the tetrammin complex Cu(NH3) +, the chemiluminescence is due to excited-singlet oxygen when the catalyst is copper flavin mononucleotide (Cu—FMN), additional emission occurs from excited flavin mononucleotide. From absorption spectroscopic measurements J. Stauff and F. Nimmerfall60> concluded that the first reaction step consists in the addition of oxygen to the copper complex ... [Pg.79]

Hamman MA, Haehner-Daniels BD, Wrighton SA, et al. Stereoselective sulfoxidation of sulin-dac sulfide by flavin-containing monooxygenases. Comparison of human liver and kidney microsomes and mammalian enzymes. Biochem Pharmacol 2000 60(1) 7-17. [Pg.104]

Rettie, A., Bogucki, B., Lim, I. and Meier, P. (1990). Steroselective sulfadioxidation of a series of alkyl P-tolyl sulfides hy microsomal and purified flavin-containing monooxygenases. Mol. Pharmacol. 37 643-651. [Pg.633]

JBC(244)2590,76JBC(251)6994>. The compounds monooxygenated by flavin-dependent enzymes include both electrophilic and nucleophilic species. These compounds can be divided into three groups for the convenience of discussion (i) amines and sulfides, (ii) aromatic compounds with electron releasing substituents, and (iii) aldehydes and ketones (Table 3). [Pg.255]

A second group of electron carriers in mitochondrial membranes are the iron-sulfur [Fe-S] clusters which are also bound to proteins. Iron-sulfur proteins release Fe3+ or Fe2+ plus H2S when acidified. The "inorganic clusters" bound into the proteins have characteristic compositions such as Fe2S2 and Fe4S4. The sulfur atoms of the clusters can be regarded as sulfide ions bound to the iron ions. The iron atoms are also attached to other sulfur atoms from cysteine side chains from the proteins. The Fe-S proteins are often tightly associated with other components of the electron transport chain. For example, the flavoproteins Flavin 1, Flavin 2, and Flavin 3 shown in Fig. 10-5 all contain Fe-S clusters as does the Q-cytochrome b complex. All of these Fe-S clusters seem to be one-electron carriers. [Pg.514]

Components of the electron transport chain in bacteria have been shown to include b- and c-type cytochromes, ubiquinone (fat-soluble substitute quinone, also found in mitochondria), ferredox (an enzyme containing nonheme iron, bound to sulfide, and having the lowest potential of any known electron-canying enzyme) and one or more flavin enzymes. Of these a cytochrome (in some bacteria, with absorption maximum at 423.5 micrometers, probably Cj) has been shown to be closely associated with the initial photoact. Some investigators were able to demonstrate, in chromatium, the oxidation of the cytochrome at liquid nitrogen temperatures, due to illumination of the chlorophyll. At the very least this implies that the two are bound very closely and no collisions are needed for electron transfers to occur. [Pg.1284]

Biological oxidation of sulfides involves cytochromes P-450 or flavin-dependent oxygenases. A chiral flavin model was prepared by Shinkai etal. and used as the catalyst in the oxidation of aryl methyl sulfides [87]. Flavinophane 30 (Scheme 6C.10) is a compound with planar chirality. It catalyzes the oxidation of sulfides with 35% H202 in aqueous methanol at -20°C in the dark. [Pg.345]

Protein Iron Inorganic sulfide Flavin EPR signal g = 1.94 oxidized reduced Molecular weight Absorption maxima of oxidized form, mp... [Pg.132]

The third structure of labile sulfur is a persulfide linkage which has been proposed by Massey and his coworkers (39) for dihydroorotate dehydrogenase. This enzyme has 2 atoms of iron, and 2 moles of labile sulfur besides its flavin moiety. They suggested that in catalysis the iron sulfide functions as an iron-sulfur radical, and the iron is not reduced by substrate. [Pg.27]

DerVartanian et al. (4 ) have examined the EPR properties of the dehydrogenase of Baugh and King (43), which has a flavin iron labile sulfide ratio of 1 28 28. They have concluded that quantitation of the four reduced iron-sulfur centers by double integration accounts for only 36% of the iron content of the preparation. They felt that in this preparation the behavior of the EPR resonances suggests the presence of unidentified iron complexes in addition to iron-sulfur centers. Ohnishi et al. (50) have examined a preparation of complex I made by Ragan and Racker... [Pg.187]

The resolved complex is composed of two fractions, a soluble part, which comprises about 15% of complex I proteins, and a water-insoluble part consisting of the rest of the protein and the bulk of complex I lipids. The soluble fraction is easily separated from the insoluble material by centrifugation. Upon fractionation with ammonium sulfate, it yields a soluble flavoprotein containing iron and labile sulfide and a dark brown protein, which contains large amounts of iron and labile sulfide but no flavin. The latter appears to be an iron-sulfur protein and exhibits an EPR signal which is characteristic of iron-sulfur center 2 of intact complex I (46). Its absorption spectrum is shown in Fig. 8. The insoluble fraction also contains equimolar amounts of iron and labile sulfide and little or no flavin. [Pg.193]

The dehydrogenase preparations obtained by acid-ethanol extraction of particles at elevated temperatures vary considerably in their content of flavin, iron, and labile sulfide, and in their activities. These differences appear to be largely a consequence of destruction of the iron-sulfur chromophore at acid pH. As seen in Fig. 10, incubation of the low molecular weight dehydrogenase preparation of Hatefl and Stempel at pH 4.8 and 38° resulted after 1 hr in nearly complete loss of labile sulfide (Fig. IOC) and reductase activity with respect to menadione, cytochrome c. [Pg.194]


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See also in sourсe #XX -- [ Pg.763 ]

See also in sourсe #XX -- [ Pg.763 ]

See also in sourсe #XX -- [ Pg.763 ]




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