NADH-dependent

Whereas ATP made in glycolysis and the TCA cycle is the result of substrate-level phosphorylation, NADH-dependent ATP synthesis is the result of oxidative phosphorylation. Electrons stored in the form of the reduced coenzymes, NADH or [FADHa], are passed through an elaborate and highly orga-... 

Methemoglobinemia Intake of excess oxidants (various chemicals and drugs) Genetic deficiency in the NADH-dependent methemoglobin reductase system (MIM 250800) Inheritance of HbM (MIM 141800)... 

The iron of Hb must be maintained in the ferrous state ferric iron is reduced to the ferrous state by the action of an NADH-dependent methemoglobin reductase system involving cytochrome reductase and cytochrome b. ... 

Inoue, K., Makino, Y. and Itoh, N. (2005) Production of (A l-chiral alcohols by a hydrogen-transfer bioreduction with NADH-dependent Leifsonia alcohol dehydrogenase (LSADH). Tetrahedron Asymmetry, 16 (15), 2539-2549. 

Fig. 1. The metabolic cycle for the synthesis and degradation of poly(3HB). (1) 3-ketothiolase (2) NADPH-dependent acetoacetyl-CoA reductase (3) poly(3HB) synthase (4) NADH-dependent acetoacetyl-CoA reductase (5), (6) enolases (7) depolymerase (8) d-(-)-3-hydroxybutyrate dehydrogenase (9) acetoacetyl-CoA synthetase (10) succinyl-CoA transferase (11) citrate synthase (12) see Sect. 3...

The kind of enantiomer [d-(-)- or l-(+)-] synthesized in the formation of the C4 intermediate varies. The acetoacetyl-CoA reductase (EC 1.1.1.36), which is NADPH-dependent, stereoselectively reduces acetoacetyl-CoA to d-(-)-3-hydroxybutyryl-CoA (R. eutropha [15]). The NADH-dependent reductase catalyzes the reduction of acetoacetyl-CoA to L-(+)-3-hydroxybutyryl-CoA. Afterwards two stereospecific crotonyl-CoA hydratases, l-(+)- and D-(-)-speci-fic, convert the L-(+)-3-hydroxybutyryl-CoA into the D-(-)-isomer (Rhodo-spirillum rubrum [16]). 

The NADPH-dependent reductase is active with C4 to C6 D-(-)-3-hy-droxyacyl-CoAs, it has no activity with L-(+)-substrates, and the reduction of acetoacetyl-CoA yields only D-(-)-3-hydroxybutyryl-CoA. The NADH-de-pendent reductase can use the L-(+)-enantiomers of these compounds and, in addition, C7, C8, and C10 L-(+)-3-hydroxyacyl-CoAs as substrates. From aceto-acetyl-CoA the NADH-dependent reductase produces only L-(+)-3-hydro-xybutyryl-CoA, but in the reverse direction it is active with both substrates [15]. 

The preference of many NADH-dependent enzymes for either re or si face of their respective substrates is known => some of these enzymes become exceptionally useful stereoselective reagents for synthesis. 

Rhin(bpy)3]3+ and its derivatives are able to reduce selectively NAD+ to 1,4-NADH in aqueous buffer.48-50 It is likely that a rhodium-hydride intermediate, e.g., [Rhni(bpy)2(H20)(H)]2+, acts as a hydride transfer agent in this catalytic process. This system has been coupled internally to the enzymatic reduction of carbonyl compounds using an alcohol dehydrogenase (HLADH) as an NADH-dependent enzyme (Scheme 4). The [Rhin(bpy)3]3+ derivative containing 2,2 -bipyridine-5-sulfonic acid as ligand gave the best results in terms of turnover number (46 turnovers for the metal catalyst, 101 for the cofactor), but was handicapped by slow reaction kinetics, with a maximum of five turnovers per day.50... 

The yeast-mediated enzymatic biodegradation of azo dyes can be accomplished either by reductive reactions or by oxidative reactions. In general, reductive reactions led to cleavage of azo dyes into aromatic amines, which are further mineralized by yeasts. Enzymes putatively involved in this process are NADH-dependent reductases [24] and an azoreductase [16], which is dependent on the extracellular activity of a component of the plasma membrane redox system, identified as a ferric reductase [19]. Recently, significant increase in the activities of NADH-dependent reductase and azoreductase was observed in the cells of Trichosporon beigelii obtained at the end of the decolorization process [25]. 

This mechanism is now considered to be of importance for the protection of LDL against oxidation stress, Chapter 25.) The antioxidant effect of ubiquinones on lipid peroxidation was first shown in 1980 [237]. In 1987 Solaini et al. [238] showed that the depletion of beef heart mitochondria from ubiquinone enhanced the iron adriamycin-initiated lipid peroxidation whereas the reincorporation of ubiquinone in mitochondria depressed lipid peroxidation. It was concluded that ubiquinone is able to protect mitochondria against the prooxidant effect of adriamycin. Inhibition of in vitro and in vivo liposomal, microsomal, and mitochondrial lipid peroxidation has also been shown in studies by Beyer [239] and Frei et al. [240]. Later on, it was suggested that ubihydroquinones inhibit lipid peroxidation only in cooperation with vitamin E [241]. However, simultaneous presence of ubihydroquinone and vitamin E apparently is not always necessary [242], although the synergistic interaction of these antioxidants may take place (see below). It has been shown that the enzymatic reduction of ubiquinones to ubihydroquinones is catalyzed by NADH-dependent plasma membrane reductase and NADPH-dependent cytosolic ubiquinone reductase [243,244]. 

Rarely, phenylketonuria results from a defect in the metabolism of biopterin, a cofactor for the phenylalanine hydroxylase pathway. The electron donor for phenylalanine hydroxylase is tetrahydrobiopterin (BH4), which transfers electrons to molecular oxygen to form tyrosine and dihydrobiopterin (QH2 Fig. 40-2 reaction 2). BH4 is regenerated from QH2 in an NADH-dependent reaction that is catalyzed by dihydropteridine reductase (DHPR), which is widely distributed. In the brain, this... 

SHEPPARD, C., TRIMMER, E., MATTHEWS, R.G., Purification and properties of NADH-dependent 5, 10-methylenetetrahydrofolate reductase (MetF) from Escherichia coli,J. Bacteriol., 1999,181, 718-725. 

ROJE, S., WANG, H., MCNEIL, S.D., RAYMOND, R.K., APPLING, D.R., SHACHAR-HILL, Y., BOHNERT, H.J., HANSON, A.D., Isolation, characterization, and functional expression of cDNAs encoding NADH-dependent methylenetetrahydrofolate reductase from higher plants, J. Biol. Chem., 1999, 274, 36089-36096. 

The successful synthetic application of this electroenzymatic system has first been shown for the in-situ electroenzymatic reduction of pyruvate to D-lactate using the NADH-dependent D-lactate dehydrogenase. Electrolysis at — 0.6 V vs a Ag/AgCl-reference electrode of 50 mL of a 0.1 M tris-HCL buffer of pH 7.5 containing pentamethylcyclopentadienyl-2,2 -bipyridinechloro-rhodium(III) (1 x 10 3 M), NAD+ (2 x 10 3 M), pyruvate (2 x 10 2 M), 1300 units D-lactate dehydrogenase (divided cell, carbon foil electrode) after 3 h resulted in the formation of D-lactate (1.4 x 10 2 M) with an enantiomeric excess of 93.5%. This means that the reaction occurred at a rate of 5 turnovers per hour with respect to the mediator with a 70% turnover of the starting material. The current efficiency was 67% [67],... 

Recently, we adopted the same system for the reduction of 4-phenyl-2-butanone to (S)-4-phenyl-2-butanol using the NADH-dependent horse liver alcohol dehydrogenase (HLADH) and S-ADH from Rhodococcus sp [68] with high enantioselectivity (Fig. 17) [69]. As mediator, we applied the low-molecular... 

Magnuson TS, Hodges-Myerson AL, Lovley DR (2000) Characterization of a membrane-bound NADH-dependent Fe + reductase from the dissimilatory Fe -reducing bacterium Geobacter sulfurreducens. FEMS Microbio Lett 185 205-211... 

To facilitate its application in organic synthesis, we developed a lyophilized cell powder of Sphingomonas sp. HXN-200 as a biohydroxylation catalyst. Hydro-xylation of A-benzyl-piperidine with such catalyst powder showed 85% of the activity of a similar hydroxylation with frozen/thawed cells, shown in Figure 15.6. The fact that rehydrated lyophilized cells are able to carry out such a reduced nicotinamide adenine dinucleotide (NADH)-dependent hydroxylation indicates that these cells are capable of retaining and regenerating NADH at rates equal to or exceeding the rate of hydroxylation. To our knowledge, this is the first example of the use of lyophilized cells for a cofactor-dependent hydroxylation. 

Kometani et al. [71] reported that baker s yeast catalyzed the asymmetric reduction of acetol to (i )-1,2-propanediol with ethanol as the energy source. The enzyme involved in the reaction was an NADH-dependent reductase, and NADH required for the reduction was supplied by ethanol oxidizing enzyme(s) in the yeast. When washed cells of baker s yeast were incubated with 10 mg ml of acetol in an ethanol solution with aeration, (k)-1,2-propanediol was formed almost stoichiometrically with an optical purity of 98.2% e. e. 

Glyoxylate reductase [EC 1.1.1.26] catalyzes the reversible reaction of glycolate with NAD+ to produce glyoxylate and NADH. The enzyme will also catalyze the NADH-dependent interconversion of hydroxypyruvate to D-glycerate. Glyoxylate reductase (NADPH) [EC... 

Examination of one real-life case may benefit the reader s understanding. Strittmatter studied the primary kinetic isotope effects arising in the NADH-dependent cytochrome bs reductase (EC 1.6.2.2). The oxidation of NADH and subsequent reduction of cytochrome bs is facilitated by the enzyme-bound FAD group, and the kinetics of the direct transfer of a hydrogen from the A-face (or pro-R) of NADH to the flavin can be monitored by the loss of the 340 run absorbance of the NADH s dihydropyridine ring. Using deuterated isotopic isomers of NADH and several related compounds, Strittmatter obtained the primary kinetic isotope effect data compiled in the table below. 

NICOTINAMIDE COENZYMES (SREC-TRAL PROPERTIES) NADH-dependent enzymes, AQUACOBALAMIN REDUCTASES BENZENE 1,2-DIOXYGENASE DEHYDROASCORBATE REDUCTASE GLUTAMATE SYNTHASE GLYOXYLATE REDUCTASE 3-HYDROXYBENZOATE 6-MONOOXY-GENASE... 

The NADH-dependent reductase, which contains a 2Fe 2S cluster and FAD as cofactors, converts the oxidized hydroxylase binuclear cluster to a diferrous state after each catalytic cycle. It should be emphasized that the reductase does not participate directly in the hydroxylation reaction its sole function is to regenerate the reduced enzyme in a separate reaction (Fox et al., 1988). The latter reacdon is reminiscent of the NADH-linked reducdon of inactive diferric RNRB2 (see Section III,B). 

Zabriski and colleagues 145, 46] first used culture fluorescence as an on-line estimate of viable biomass during the batch cultivation of Saccharomyces cere-visiae, a species of Streptomyces, and a species of Thermoactinomyces. They simply linearized the fluorescence to biomass data in order to find a direct function between NADH-dependent culture fluorescence and biomass concentration in the bioreactor. In the following years several other authors reported - on the basis of these results - on the estimation of biomass concentration from culture fluorescence data as shown in Table 1. 

The monitoring of viable cell mass even in technical media is possible with this technique. However, fluorescence medium components might drastically interfere with the NADH-dependent fluorescence and signal disturbances occur caused by air bubbles (lowering the sensor readings) or large amounts of scattering particles. 

While most appfications were performed in suspended cell cultures some authors showed that the application of NADH-dependent fluorescence monitoring is also possible in immobifized cell systems. Here the growth of Clostridium acetobutylicum and the Saccharomyces cerevisiae immobilized in different calcium alginate structures was studied. However, calibration of the culture fluorescence signal with the biomass concentration was not possible but qualitatively an increasing biomass also led to an increase in the fluorescence signals. 

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