Extracts of representative bacterial strains from the various families of photosynthetic prokaryotes are demonstrated to possess significant levels of sulfite reductase [EC 1.8.99.1; hydrogen-sulfide: (acceptor)oxidoreductase] activity with reduced methyl viologen as electron donor, but not NADPH(2). The enzyme is localized primarily in the soluble fraction of the extracts, in contrast to adeny...

Previous papers in this series have reported the hypoxanthinedependent oxidation of sulfite by cyanide-inhibited xanthine oxidase (1) and experiments which permitted postulation of the structure of the active site of this enzyme (2). In the present study, xanthine oxidase acting on its substrates has been found to initiate the aerobic oxidation of sulfite by free radical chains of great length ...

We studied the kinetics of reactions of cob(I)alamin and cob(I)inamide with thiosulfate, sulfite, and dithionite by UV-Visible (UV-Vis) and stopped-flow spectroscopy. We found that the two Co(I) species were oxidized by these sulfur-containing compounds to Co(II) forms: oxidation by excess thiosulfate leads to penta-coordinate complexes and oxidation by excess sulfite or dithionite leads to hex...

Sulfur K-edge X-ray absorption spectroscopy (XAS) and density functional theory (DFT) calculations have been used to determine the electronic structures of two complexes [Mo(IV)O(bdt)2](2-) and [Mo(VI)O2(bdt)2](2-) (bdt = benzene-1,2-dithiolate(2-)) that relate to the reduced and oxidized forms of sulfite oxidase (SO). These are compared with those of previously studied dimethyl sulfoxide reduc...

A reduced nicotinamide adenine dinucleotide phosphate (NADPH)-specific enzyme from Escherichiu wti, isolated as a nitrite reductase, catalyzed the reductions of both nitrite and hydroxylamine to ammonia, and the ratio of the two activities remained constant during partial purification (1). The demonstration in the same species of an NADPH-specific enzyme catalyzing the reductions of hydroxylami...

Members of the enolase mechanistically diverse superfamily catalyze a wide variety of chemical reactions that are related by a common mechanistic feature, the abstraction of a proton adjacent to a carboxylate group. Recent investigations into the function and mechanism of the phosphosulfolactate synthase encoded by the ComA gene in Methanococcus jannaschii have suggested that ComA, which cataly...

Sulfurous compounds: sodium sulfite Na2SO3 (E 221), sodium bisulfite NaHSO, (E 222), and sodium metabisulfite Na2S2O5 (E 223) are largely used as antioxidants in many pharmaceutical formulations. A method for determination of sodium metabisulfite in parenteral formulations containing tartrate ions was developed. High-performance ion chromatography (HPIC) method with suppressed conductivity dete...

Transposon Tn5 insertions causing anaerobic cysteine auxotrophy were isolated from a Salmonella typhimurium cysI parent (auxotrophic under aerobic but not anaerobic conditions). Insertions in one mutant group appeared to be in cysG. A second group of insertions, designated asr (anaerobic sulfite reduction), were located near map unit 53 on the S. typhimurium chromosome. They did not cause aerob...

Abstract Surface functional groups have a strong influence on the deposition and final state of nanoparticles adsorbed to surface, role discussed by Professor Spencer in his work. This tribute explores formation hydroxyls, thiosulfates, sulfites sulfur atoms carbon (HOPG) surfaces their effect gold palladium from aqueous solutions. Hydroxyls formed ammonium hydroxide treatment identical behavio...