Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P47989 (xanthine oxidase)
 8,633 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The reaction of superoxide with reduced glutathione (GSH) was studied with two O-.2-producing systems: xanthine oxidase using xanthine or acetaldehyde as substrates, and secondly, quinol autoxidation. The capability of GSH to quench superoxide radicals was detected by lowered O-.2-mediated cytochrome c3+ reduction. The formation of the oxidation products, glutathione disulfide (GSSG) and glutathione sulfonate (the latter at levels of about 6-15% compared to GSSG), was dependent on the O-.2 production and was inhibited by superoxide dismutase. The presence of GSH together with an O-.2-producing system led to an extra uptake of oxygen, which was also depressed by superoxide dismutase. The observed O2 uptake was accounted for by the formation of GSSG and GSO-3 from GSH; the data are in accordance with a mechanism involving thiyl radicals. Low-level chemiluminescence measurement indicated the formation of excited oxygen species. The intensity of photoemission was dependent on the GSH concentration and on the O-.2 production rate. Chemiluminescence was inhibited by superoxide dismutase and also by glutathione peroxidase, but not by catalase or OH. quenchers. Spectral analysis and the effects of 1,4-diazabicyclo[2.2.2]octane and sodium azide indicated the contribution of singlet molecular oxygen to the light emission. It is suggested that singlet oxygen results from an intermediate oxygen addition product such as a glutathione peroxysulphenyl radical.
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PMID:Oxidation of glutathione by the superoxide radical to the disulfide and the sulfonate yielding singlet oxygen. 631 88

1,4,8,11-tetraazacyclotetradecane (cyclam), which is one of the most extensively investigated ligands in coordination chemistry, in its protonated forms, can play the role of host toward cyanide metal complexes. We have investigated the acid-driven adducts formed in acetonitrile-dichloromethane (1:1 v/v) solution by [Ru(bpy)(CN)4](2-) with 1,4,8,11-tetrakis(naphthylmethyl)cyclam (1) and a dendrimer consisting of a cyclam core appended with 12 dimethoxybenzene and 16 naphthyl units (2). [Ru(bpy)(CN)4](2-), 1, and 2 exhibit characteristic absorption and emission bands, in distinct spectral regions, that are strongly affected by addition of acid. When a solution containing equimolar amounts of [Ru(bpy)(CN)4](2-) and 1 or 2 is titrated by trifluoroacetic acid, or when [Ru(bpy)(CN)4](2-) is titrated with (1.2H)2+ or (2.2H)2+, [[Ru(bpy)(CN)4](2-).(2H+).1] or [[Ru(bpy)(CN)4](2-).(2H+).2] adducts are formed in which the fluorescence of the naphthyl units is strongly quenched by very efficient energy transfer to the metal complex, as shown by the sensitized luminescence of the latter. The [[Ru(bpy)(CN)4]2-.(2H+).1] and [[Ru(bpy)(CN)4](2-).(2H+).2] adducts can be disrupted (i) by addition of a base (1,4-diazabicyclo[2.2.2]octane), yielding the starting species [Ru(bpy)(CN)4](2-) and 1 or 2, or (ii) by further addition of triflic acid, with formation of (1.2H)2+ or (2.2H)2+ and protonated forms of [Ru(bpy)(CN)4](2-). It is shown that upon stimulation with two chemical inputs (acid and base) both [[Ru(bpy)(CN)4](2-).(2H+).1] and [[Ru(bpy)(CN)4](2-).(2H+).2] exhibit two distinct optical outputs (a naphthalene-based and a Ru(bpy)-based emission) that behave according to an XOR and an XNOR logic, respectively.
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PMID:Proton-driven self-assembled systems based on cyclam-cored dendrimers and [Ru(bpy)(CN)4]2-. 1560 Mar 49