Quinone oxidoreductases are a class of membrane enzymes that catalyse the oxidation or reduction of membrane-bound quinols/quinones. The conversion of quinone/quinol by these enzymes is difficult to study because of the hydrophobic nature of the enzymes and their substrates. We describe some biochemical properties of quinones and quinone oxidoreductases and then look in more detail at two model...

A generally applicable direct synthesis of cyanoarenes from quinones is presented. Particular emphasis is placed on the preparation of precursors and target molecules relevant for organic materials, including halogenated cyanoarenes and larger cyanated acenes. The reaction and work-up protocols are adjusted for the challenges presented by the different substrates and products. Screening results...

This review considers the interaction of Complex I with different redox acceptors, mainly homologs and analogs of the physiological acceptor, hydrophobic Coenzyme Q. After examining the physical properties of the different quinones and their efficacy in restoring mitochondrial respiration, a survey ensues of the advantages and drawbacks of the quinones commonly used in Complex I activity determ...

We have developed the first example of hypervalent iodine(V)-catalyzed regioselective oxidation of phenols to o-quinones. Various phenols could be oxidized to the corresponding o-quinones in good to excellent yields using catalytic amounts of sodium salts of 2-iodobenzenesulfonic acids (pre-IBSes) and stoichiometric amounts of Oxone® as a co-oxidant under mild conditions. The reaction rate of I...

The synthesis of 3-amino-2-methoxycarbonyl-4,7-dimethoxybenzo[b]thiophene (5) and benzothieno[3,2-d][1,3]oxazin 15 from 3,6-dimethoxy-2-nitrobenzaldehyde (1) is reported. Benzo[b]thiophene-4,7-quinones 9 and 10 were prepared in good yields by oxidative deprotection of the corresponding dimethoxybenzothiophenes 8 and 7. Cycloaddition reaction of quinone 8 with 1-(E)-trimethylsilyloxy-1,3-butadie...

NAD(P)H/quinone acceptor oxidoreductase type 1 (QR1) protects cells from cytotoxic and neoplastic effects of quinones though two-electron reduction. Kinetic experiments, docking, and binding affinity calculations were performed on a series of structurally varied quinone substrates. A good correlation between calculated and measured binding affinities from kinetic determinations was obtained. Th...

Representative strains of each of the named species of Legionella were examined for isoprenoid quinones by reverse-phase thin-layer chromatography. All strains contained three or more ubiquinones (Q9, Q10, Q11, Q12, Q13) which were useful for placing the species into one of three distinct groups. Group 1 contained L. longbeachae, L. bozemanii, L. dumoffi, and L. gormanii; group 2 contained only...

An amperometric biosensor based on the enzyme polyphenoloxidase (PPO), which makes the bioelectrocatalysis of phenolic compounds, was developed and optimized using cathecol as substrate. Polyethersulphone membranes were used for enzyme immobilization. Polyphenoloxidase oxidizes monophenols (cresolase activity) and diphenols (catecholase activity) into the corresponding o-quinones; the o-quinone...