The flavin adenine dinucleotide-dependent glucose dehydrogenase (FAD-GDH) from Aspergillus species require suitable redox mediators to transfer electrons from the enzyme to the electrode surface for the application of bioelectrical devices. Although several mediators for FAD-GDH are already in use, they are still far from optimum in view of potential, kinetics, sustainability, and cost-effectiv...

In order to clarify the poorly understood mechanisms of two-electron reduction of quinones by flavoenzymes, we examined the quinone reductase reactions of a member of a structurally distinct old yellow enzyme family, Enterobacter cloacae PB2 pentaerythritol tetranitrate reductase (PETNR). PETNR catalyzes two-electron reduction of quinones according to a 'ping-pong' scheme. A multiparameter anal...

A sensitive and selective chemiluminescence assay for the determination of quinones was developed. The method was based on generation of reactive oxygen species through the redox reaction between quinone and dithiothreitol as reductant, and then the generated reactive oxygen was detected by luminol chemiluminescence. The chemiluminescence was intense, long-lived, and proportional to quinone con...

To search for possible anti-tumor agents or anti-tumor promoters among natural or synthetic products, we used cyclic voltammetry to determine the reduction-oxidation potentials of heterocyclic quinones in phosphate buffer at pH 7.2. We determined the growth inhibitory- and cytotoxic activities of 12 heterocyclic quinone anti-tumor agent candidates against a panel of 39 human cancer cell lines (...

Among all the chemical and biotechnological strategies implemented to extract energy from oxygenic photosynthesis, several concern use of intact photosynthetic organisms (algae, cyanobacteria…). This means rerouting (fully or partially) electron flow chain an outer collecting electrode thus generating a photocurrent. While diverting electrons living biological systems is encouraging approach, t...

The one-electron reduction of quinones to semiquinones and the subsequent autooxldatlon of the semlqulnone back to the quinone can generate large quantities of superoxide (0~) (1,2). This reductlon-oxldation process, known as redox cycling, is anion radical catalyzed by a variety of cellular flavoproteins and is thought to be responsible for many of the therapeutic and toxic effects of quinonoi...