Two-electron reduction of benzoquinone ansamycin (BA) heat shock protein (Hsp) 90 inhibitors by NAD(P)H:quinone oxidoreductase 1 (NQO1) to hydroquinone ansamycins (BAH2s) leads to greater Hsp90 inhibitory activity. BAs can also be metabolized by one-electron reductases and can interact with glutathione, reactions that have been associated with toxicity. Using a series of BAs, we investigated th...

Introduction Quinones are ubiquitous dietary compounds. Reduction of quinones by one-electron reduction systems (cytochrome P450 reductases) results in the formation of reactive semiquinones that can be re-oxidized to quinones by molecular oxygen with the formation of superoxide radical (02-*). Superoxide can lead to the formation of other reactive oxygen species, including the highly mutagenic...

The mechanisms by which microbial species exchange electrons are of interest because interspecies electron transfer can expand the metabolic capabilities of microbial communities. Previous studies with the humic substance analog anthraquinone-2,6-disulfonate (AQDS) suggested that quinone-mediated interspecies electron transfer (QUIET) is feasible, but it was not determined if sufficient energy ...

NAD(P)H:quinone oxidoreductase 1 (NQO1) catalyses the reduction of quinoid compounds to hydroquinones, preventing the generation of free radicals and reactive oxygen. A "C" to "T" transversion at position 609 of NQO1, leading to a nonsynonymous amino acid change (Pro187Ser, P187S), results in an altered enzyme activity. No NQO1 protein activity was detected in NQO1(609)TT genotype, and low to i...

Previous work has shown that the white rot fungus Coriolopsis rigida degraded wheat straw lignin and both the aliphatic and aromatic fractions of crude oil from contaminated soils. To better understand these processes, we studied the enzymatic composition of the ligninolytic system of this fungus. Since laccase was the sole ligninolytic enzyme found, we paid attention to the oxidative capabilit...

UNLABELLED NAD(P)H:quinone oxidoreductase 1 (NQO1) is a cytosolic enzyme that catalyzes the two-electron reduction of quinoid compounds into hydroquinones, their less toxic form. A sequence variant at position 609 (C --> T) in the NQO1 gene encodes an enzyme with reduced quinone reductase activity in vitro and thus was hypothesized to affect cancer susceptibility. We conducted meta-analyses foc...

The inhibition of the spreading effect of hyaluronidase by the previous administration of sodium salicylate was reported by Guerra and Robles Gil (1). Subsequent investigations indicated that this phenomenon could not be explained on the basis of the direct inhibition of hyaluronidase by salicylates, since such inhibition could only be demonstrated in vitro at high salicylate concentrations (2-...

NAD(P)H:quinone oxidoreductase 1 (NQO1) is an FAD containing quinone reductase that catalyzes the 2-electron reduction of a broad range of quinones. The 2-electron reduction of quinones to hydroquinones by NQO1 is believed to be a detoxification process since this reaction bypasses the formation of the highly reactive semiquinone. NQO1 is expressed at high levels in normal epithelium, endotheli...

Experiments using purified recombinant human NAD(P)H:quinone oxidoreductase 1 (NQO1) revealed that the auto-oxidation of fully reduced protein resulted in a 1:1 stoichiometry of oxygen consumption to NADH oxidation with the production of hydrogen peroxide. The rate of auto-oxidation of fully reduced NQO1 was markedly accelerated in the presence of superoxide (O(2)(*)(-)), whereas the addition o...

ENOX (ECTO-NOX) proteins are proteins of the external surface of the plasma membrane that catalyze oxidation of both NADH and hydroquinones as well as carry out protein disulfide-thiol interchange. They exhibit both prion-like and time-keeping (clock) properties. The oxidative and interchange activities alternate to generate a regular period of 24 min in length. Here we report the cloning, expr...