Disease relevance of duroquinol

• Kinetics of membrane-bound nitrate reductase A from Escherichia coli with analogues of physiological electron donors--different reaction sites for menadiol and duroquinol [1].
• This chromophore is reduced by NADPH or duroquinol and is missing in cell lysates derived from a patient with chronic granulomatous disease [2].

High impact information on duroquinol

• In broken mitochondria, inhibition of oxidative metabolism was found for NADH or duroquinol as substrate in the presence of 100 mumol/L lithocholate (0.2 mumol/mg protein) and for duroquinol in the presence of 100 mumol/L chenodeoxycholate [3].
• Their effect on thermogenin was monitored as the capacity of the cells for reverse electron transport from durohydroquinone [4].
• Glucagon caused no increase in mitochondrial respiration in situ either in the presence of the physiological substrates or in the presence of durohydroquinone [5].
• The granule cytochrome was compared to mitochondrial cytochrome b and, in spite of similar molecular weights and optical spectra, these two proteins were found to be different by the following criteria: 1) amino acid composition, 2) NH2-terminal analysis, 3) interaction with antimycin, and 4) reduction with durohydroquinone [6].
• Finally, in our hands, both the purified pMMO-detergent complex and pMMO-enriched membranes exhibit high NADH-sensitive as well as duroquinol-sensitive specific activity [7].

Biological context of duroquinol

• Aging decreased the rate of oxidative phosphorylation using durohydroquinone, an electron donor to complex III, in IFM only [8].
• Modulation of electron flow by addition of methyl viologen with or without duroquinol, or in a NAD(P)H dehydrogenase-deficient mutant, affects the phosphorylation level of PII [9].
• To examine whether electron transfer from menadiol and duroquinol for nitrate reduction requires the presence of all of the Fe-S centres, we have studied the steady-state kinetics of mutants with beta subunits that lack an Fe-S centre [1].
• 4. We found that oxygen consumption using succinate or durohydroquinone + FCCP as substrates, as well as ATP production were not affected by cold exposure [10].

Anatomical context of duroquinol

• Oxidative metabolism of L-glutamate, succinate and duroquinol was decreased in liver mitochondria from bile duct ligated rats [11].
• The reduction of cyctochromes c + c1 by durohydroquinone and ferrocyanide in electron transport particles (ETP) and intact cytochrome c-depleted beef heart mitochondria has been studied [12].
• The pre-steady-state kinetics of the reduction of the prosthetic groups of QH2:cytochrome c oxidoreductase in bovine heart submitochondrial particles were studied in relation to the kinetics of the Q-10 reduction, using duroquinol as substrate [13].

Associations of duroquinol with other chemical compounds

• In intact mitochondria, succinate and duroquinol-driven reduction of endogenous cytochrome c is greater than 95% at all ionic strengths, indicating that cytochrome c functions as a common pool irrespective of its diffusion mode [14].
• The NDH and NADH were added to maintain a high duroquinol/duroquinone ratio [15].
• NAD(P)H:quinone oxidoreductase 1 (NQO1) plays a dominant role in the reduction of the quinone compound 2,3,5,6-tetramethyl-1,4-benzoquinone (duroquinone, DQ) to durohydroquinone (DQH2) on passage through the rat lung [16].
• Stopped-flow kinetics of heme oxidation by potassium nitrate indicates that there are two distinct reactions, depending on whether the hemes were previously reduced by menadiol or by duroquinol [17].
• Experiments on specific segments of the respiratory chain showed that cadmium does not inhibit electron flow through cytochrome oxidase, whereas the inhibition of duroquinol oxidation clearly demonstrates an impairment of electron flow through site 2, the ubiquinone-b-cytochrome c1 complex [18].

Gene context of duroquinol

• C. reinhardtii and S. obliquus complexes contain the Rieske iron-sulfur protein (present in approx 1:1 molar ratio to cytochrome f) and each catalyzes a DBMIB- and DNP-INT-sensitive electron transfer from duroquinol to spinach plastocyanin [19].
• Under such circumstances, the addition of a limited amount of either succinate or duroquinol leads to a multiphasic reduction and oxidation of cytochrome b [20].
• Assays of partial electron transport activities indicate a site of inhibition in the region between the site of duroquinol oxidation and cytochrome c reduction [21].
• Finally, the addition of the type 2 NADH:quinone oxidoreductase complex (NADH dehydrogenase [NDH]) from M. capsulatus Bath, along with NADH and duroquinol, to enzyme assays increased the activity of purified preparations [15].
• Duroquinol was a suitable reducing agent, and pMMO was stabilized by bovine serum albumin (BSA) [22].

Analytical, diagnostic and therapeutic context of duroquinol

• The effects of glucagon treatment on duroquinol oxidation and the inhibitor titrations could not be mimicked by increasing the matrix volume, nor totally reversed by aging of mitochondria [23].

References