DT-diaphorase catalysed the reduction of 1,4-naphthoquinones with hydroxy, methyl, methoxy and glutathionyl substituents at the expense of reducing equivalents from NADPH. The initial rates of quinone reduction did not correlate with either the half-wave reduction potential (E1/2) value (determined by h.p.l.c. with electrochemical detection against an Ag/AgCl reference electrode) or the partiti...

Knudsen flow experiments and its interpretation in terms of adsorption/desorption kinetics as well quantitative uptake on substrates interest is presented together with the description critical design parameters Flow Reactor (KFR). Hitherto focused almost exclusively phase exposing a virgin substrate to interacting gases, we now extend experiment desorption at ambient temperature. We present an...

NAD(P)H:quinone oxidoreductase (NQO1) and dihydronicotinamide riboside:quinone oxidoreductases (NQO2) are cytosolic flavoproteins that catalyze the two-electron reduction of quinones and quinoid compounds to hydroquinones, thereby promoting detoxification and preventing the formation of highly reactive oxygen species, which lead to DNA and cell damage. Two NQO isoforms, designated NQO1 and NQO2...

Quinones represent a class of toxicological intermediates, which can create a variety of hazardous effects in vivo including, acute cytotoxicity, immunotoxicity, and carcinogenesis. In contrast, quinones can induce cytoprotection through the induction of detoxification enzymes, anti-inflammatory activities, and modification of redox status. The mechanisms by which quinones cause these effects c...

The membrane-bound heterotrimeric nitrate reductase A (NarGHI) catalyzes the oxidation of quinols in the cytoplasmic membrane of Escherichia coli and reduces nitrate to nitrite in the cytoplasm. The enzyme strongly stabilizes a menasemiquinone intermediate at a quinol oxidation site (Q(D)) located in the vicinity of the distal heme b(D). Here molecular details of the interaction between the sem...

Padi merupakan komoditas pangan yang memiliki peranan terpenting dalam memenuhi kebutuhan pokok masyarakat Indonesia. Ekstensifikasi produksi padi dapat dilakukan dengan memanfaatkan lahan marjinal seperti salin. Lahan salin kadar garam tinggi akibat intrusi air laut maupun tingginya laju evaporasi. Pengembangan budidaya di kendala berupa serangan patogen busuk pelepah (Rhizoctonia solani). Alt...

External NADH and succinate were oxidized at similar rates by soybean (Glycine max) cotyledon and leaf mitochondria when the cytochrome chain was operating, but the rate of NADH oxidation via the alternative oxidase was only half that of succinate. However, measurements of the redox poise of the endogenous quinone pool and reduction of added quinones revealed that external NADH reduced them to ...

Levodopa and dopamine are naturally occurring catecholamines with antitumor activity in several experimental tumor systems. Previous studies suggested that their cytotoxic effect was related in part to their inhibitory effect upon DNA polymerase. We have examined the effects of levodopa, dopamine, levodopa methyl ester, norepinephrine, and the analog 3,4dihydroxybenzylamine upon human and murin...

Levodopa and dopamine are naturally occurring catecholamines with antitumor activity in several experimental tumor systems. Previous studies suggested that their cytotoxic effect was related in part to their inhibitory effect upon DNA polymerase. We have examined the effects of levodopa, dopamine, levodopa methyl ester, norepinephrine, and the analog 3,4-dihydroxybenzylamine upon human and muri...

Most bacteria contain soluble quinone-reducing flavoenzymes. However, no biological benefit for this activity has previously been demonstrated. ChrR of Pseudomonas putida is one such enzyme that has also been characterized as a chromate reductase; yet we propose that it is the quinone-reducing activity of ChrR that has the greatest biological significance. ChrR reduces quinones by simultaneous ...