Relation between reduced nicotinamide adenine dinucleotide oxidation and amino acid transport in membrane vesicles from Bacillus subtilis.

The rate of reduced nicotinamide adenine dinucleotide (NADH) oxidation by membrane vesicles from Bacillus subtilis W23 increases three- to fourfold during logarithmic growth, reaching maximal levels in early stationary phase. Initial rates of L-proline, L-alanine, and L-glutamate transport energized by NADH closely parallel the increase in NADH oxidation. In vesicles prepared at different stages of growth, a constant number of NADH molecules varying from 150 to 260 have to be oxidized to transport one molecule of amino acid. Membrane vesicles from B. subtilis aroD (strain RB163), a mutant defective in menaquinone synthesis, do not transport amino acids in the presence of NADH. Ascorbate plus phenazine methosulfate, however, energizes amino acid transport equally well as in vesicles of B. subtilis W23. NADH oxidation and NADH-driven amino acid transport can be restored instantaneously by the addition of menadione (vitamin K3).     

Coupling between reduced nicotinamide adenine dinucleotide oxidation and metabolite transport in renal brush border membrane vesicles

In a previous communication [Giménez-Gallego, G., Benavides, J., García, M.L., & Valdivieso, F. (1980) Biochemistry (preceding paper in this issue)] we have reported the occurrence of a NADH oxidase activity in the renal brush border membranes. The brush border membranes can utilize the energy from the oxidation of NADH to drive the transport of amino acids (aspartic and glutamic acids), organic acids, and the lipophilic cation tetraphenylphosphonium (TPP). The coupling between NADH oxidation seems to be due to the formation of a proton electrochemical gradient (delta-mu H+) as indicated by the effect of specific ionophores. This system may be implicated in the reabsorption process in the renal tubules and in the maintenance of the delta-mu H+ (positive and acidic in the luminal side) previously described in the renal tubules "in vivo".     

Internally generated reduced nicotinamide adenine dinucleotide as a substrate for glycine transport by membrane vesicles of Paracoccus denitrificans.

Internally generated reduced nicotinamide adenine dinucleotide was the most efficient substrate for glycine transport by membrane vesicles of Paracoccus denitrificans.     

Formation of reduced nicotinamide adenine dinucleotide peroxide

Incubation of NADH at neutral and slightly alkaline pH leads to the gradual absorption of 1 mol of H+. This uptake of acid requires oxygen and mainly yields anomerized NAD+ (NAD+), with only minimal formation od acid-modified NADH. The overall stoichiometry of the reaction is: NADH + H+ + 1/2O2 leads to H2O + NAD+, with NADH peroxide (HO2-NADH+) serving as the intermediate that anomerizes and breaks down to give NAD+ and H2O2. The final reaction reaction mixture contains less than 0.1% of the generated H2O2, which is nonenzymically reduced by NADH. The latter reaction is inhibited by catalase, leading to a decrease in the overall rate of acid absorption, and stimulated by peroxidase, leading to an increase in the overall rate of acid absorption. Although oxygen can attack NADH at either N-1 or C-5 of the dihydropyridine ring, the attack appears to occur primarily at N-1. This assignment is based on the inability of the C-5 peroxide to anomerize, whereas the N-1 peroxide, being a quaternary pyridinium compound, can anomerize via reversible dissociation of H2O2. The peroxidase-catalyzed oxidation of NADH by H2O2 does not lead to anomerization, indicating that anomerization occurs prior to the release of H2O2. Chromatography of reaction mixtures on Dowex 1 formate shows the presence of two major and several minor neutral and cationic degradation products. One of the major products is nicotinamide, which possibly arises from breakdown of nicotinamide-1-peroxide. The other products have not been identified, but may be derived from other isomeric nicotinamide peroxides.     

Effect of nicotinamide adenine dinucleotide on the membrane-associated reduced nicotinamide adenine dinucleotide oxidase of Mycobacterium phlei.

NAD+ had a biphasic effect on the NADH oxidase activity in electron transport particles from Mycobacterium phlei. The oxidase was inhibited competitively by NAD+ at concentrations above 0.05 mM. NAD+ in concentrations from 0.02 to 0.05 mM resulted in maximum stimulation of both NADH oxidation and oxygen uptake with concentrations of substrate both above and below the apparent K-M. Oxygen uptake and cyanide sensitivity indicated that the NAD+ stimulatory effect was linked to the terminal respiratory chain. The stimulatory effect was specific for NAD+. NAD+ was also specific in protecting the oxidase during heating at 50 degrees and against inactivation during storage at 0 degrees. NAD+ glycohydrolase did not affect stimulation nor heat protection of the NADH oxidase activity if the particles were previously preincubated with NAD+. Binding studies revealed that the particles bound approximately 3.6 pmol of [14C1NAD+ per mg of electron transport particle protein. Although bound NAD+ represented only a small fraction of the total added NAD+ necessary for maximal stimulation, removal of the apparently unbound NAD+ by Sephadex chromatography revealed that particles retained the stimulated state for at least 48 hours. Further addition of NAD+ to stimulated washed particles resulted in competitive inhibition of oxidase activity. Desensitization of the oxidase to the stimulatory effect of NAD+ was achieved by heating the particles at 50 degrees for 2 min without appreciable loss of enzymatic activity. Kinetic studies indicated that addition of NADH to electron transport particles prior to preincubation with NAD+ inhibited stimulation. In addition, NADH inhibited binding of [14C]NAD+. The utilization of artificial electron acceptors, which act as a shunt of the respiratory chain at or near the flavoprotein component, indicated that NAD+ acts as at the level of the NADH dehydrogenase at a site other than the catalytic one resulting in a conformational change which causes restoration as well as protection of oxidase activity.     

Stimulation of transport into Escherichia coli membrane vesicles by internally generated reduced nictotinamide adenine dinucleotide

Membrane vesicles containing internal alcohol dehydrogenase and nicotinamide adenine dinucleotide (NAD) were prepared from Escherichia coli ML308-225. Upon the addition of ethanol, these vesicles respired and transported several amino acids. Transport rates driven by internally generated reduced NAD (NADH) were about 60 to 80% of that stimulated by d-lactate. This transport was inhibited by cyanide and anaerobiosis. Ferricyanide, a nonpermeable electron acceptor, inhibited transport stimulated by external NADH, but not that stimulated by internally generated NADH.     

Ion transport and respiratory control in vesicles formed from reduced nicotinamide adenine dinucleotide coenzyme Q reductase and phospholipids.

NADH-coenzyme Q reductase from bovine heart mitochondria (complex I) was incorporated into phospholipid vesicles by the cholate dialysis procedure. Mixtures of purified phosphatidylcholine and phosphatidylethanolamine were required. Oxidation of NADH by coenzyme Q1 catalyzed by the reconstituted vesicles was coupled to proton translocation, directed inward, with an H+/2e ratio greater than 1.4. Similar experiments measuring proton translocation in submitochondrial particles gave an H+/2e ratio of 1.8. The proton translocation in both systems was not seen in the presence of uncoupling agents and was in addition to the net proton uptake from the reduction of coenzyme Q1 by NADH. Electron transfer in the reconstituted vesicles also caused the uptake of the permeant anion tetraphenylboron. The rate of electron transfer by the reconstituted vesicles was stimulated about 3-fold by uncouplers or by valinomycin plus nigericin and K+ ions. The results indicate that energy coupling can be observed with isolated NADH-coenzyme Q reductase if the enzyme complex is properly incorporated into a phospholipid vesicle.     

Bull semen nicotinamide adenine dinucleotide nucleosidase. VI. Fluorescence studies of the enzyme with reduced nicotinamide adenine dinucleotide

The binding of NADH to bull semen NAD nucleosidase was observed to be accompanied by a considerable enhancement of the fluorescence of NADH. The fluorescence enhancement observed in the binding of NADH to the enzyme was utilized to study the stoichiometry of binding of this compound to the enzyme. Results obtained from the fluorescence titration of the enzyme with NADH indicated the binding of one mole of NADH per mole of enzyme (36,000 g). The dissociation constant for the enzyme-NADH complex was determined to be 2.52 × 10^?6m. NADH was also found to be a very effective competitive inhibitor of the NADase-catalyzed hydrolysis of NAD, and the inhibitor dissociation constant (K_I) for the enzyme-NADH complex was determined to be 2.99 × 10^?6m which was in good agreement with the value obtained from the fluorescence titration experiments.     

The problem of reduced nicotinamide adenine dinucleotide oxidation in glyoxysomes

Phototransformation of phytochrome in lettuce seeds (Lactuca sativa L. var. Grand Rapids) was examined by testing germination responses of seeds irradiated at various temperatures. Temperature variations from 0 to 50 C had no influence on the germination of partially hydrated seeds (about 15% water content) irradiated with either red or far red light prior to imbibition. At −15 C far red light more effectively retarded germination than red light promoted it. No effective phototransformation was detected at −79 C or −196 C.     

Nitrite reductase of Escherichia coli specific for reduced nicotinamide adenine dinucleotide

Kemp, John D. (University of California, Los Angeles), and Daniel E. Atkinson. Nitrite reductase of Escherichia coli specific for reduced nicotinamide adenine dinucleotide. J. Bacteriol. 92:628-634. 1966.-A nitrite reductase specific for reduced nicotinamide adenine dinucleotide (NADH(2)) appears to be responsible for in vivo nitrite reduction by Escherichia coli strain Bn. In extracts, the reduction product is ammonium, and the ratio of NADH(2) oxidized to nitrite reduced or to ammonium produced is 3. The Michaelis constant for nitrite is 10 mum. The enzyme is induced by nitrite, and the ability of intact cells to reduce nitrite parallels the level of NADH(2)-specific nitrite reductase activity demonstrable in cell-free preparations. Crude extracts of strain Bn will also reduce hydroxylamine, but not nitrate or sulfite, at the expense of NADH(2). Kinetic observations indicate that hydroxylamine and nitrite may both be reduced at the same active site. The high apparent Michaelis constant for hydroxylamine (1.5 mm), however, seems to exclude hydroxylamine as an intermediate in nitrite reduction. In vitro activity is enhanced by preincubation with nitrite, and decreased by preincubation with NADH(2).     

Masking of Bacillus megaterium KM membrane reduced nicotinamide adenine dinucleotide oxidase and solubilization studies

Solubilization of a reduced nicotinamide adenine dinucleotide (NADH)-2,6 dichlorophenol indophenol (DCIP) oxidoreductase associated with the membrane NADH oxidase system of Bacillus megaterium KM was effected by treatment with 0.2% sodium deoxycholate, 8 m urea, or buffer (pH 9.0) in the presence of ethyl-enediaminetetraacetate. These treatments inactivated membrane NADH oxidase. It was found that membrane NADH oxidase and NADH-DCIP oxidoreductase were masked in membranes. Several procedures, including brief sonic oscillation, treatment with 0.05% deoxycholate, prolonged stirring at 4 C with 10% glycerol, and washing in the absence of Mg(2+), unmasked the oxidase and oxidoreductase activities. It was necessary to study the masking and unmasking of these activities to quantitate adequately the effects of solubilization procedures. Further information on the localization of oxidase and oxidoreductase in subcellular fractions and the effects of electron transport inhibitors on NADH oxidation was also obtained.     

Generation of reduced nicotinamide adenine dinucleotide for nitrate reduction in green leaves

An in vivo assay of nitrate reductase activity was developed by vacuum infiltration of leaf discs or sections with a solution of 0.2 m KNO₃ (with or without phosphate buffer, pH 7.5) and incubation of the infiltrated tissue and medium under essentially anaerobic conditions in the dark. Nitrite production, for computing enzyme activity, was determined on aliquots of the incubation media, removed at intervals.     

Mechanism of transfer of reduced nicotinamide adenine dinucleotide among dehydrogenases

The pathway for the transfer of NADH from one dehydrogenase (E1) to another dehydrogenase (E2) has been investigated by studying the E2-catalyzed reduction of S2 by NADH. The experimental conditions are that the concentration of E1 exceeds that of NADH, which in turn is very much greater than E2; hence, the concentration of free (aqueous) NADH is exceedingly low. The rate of reduction of S2 will hence be very slow if unliganded aqueous NADH is required for the E2-catalyzed reaction. Our results with eight dehydrogenases are entirely consistent with the direct transfer of NADH between E1 and E2 whenever the two enzymes transfer hydrogen via opposite faces (A and B) of the nicotinamide ring. Whenever the two enzymes are both A or both B, NADH transfer occurs only via the aqueous solvent. Some mechanistic inferences and their possible physiological significance are discussed.     

Preparation and storage of isotopically labeled reduced nicotinamide adenine dinucleotide

A method for obtaining highly purified NADH in a dry, solid, and stable form is described. The method involves improvements of the ion-exchange and reversed-phase chromatographic procedures of C. J. Newton and S. M. Faynor, and D. B. Northrop (Anal. Biochem., 1983, 132, 50-53). The necessary time to prepare pure NADH has been reduced to a few hours. The final product, obtained by drying the nucleotide from absolute ethanol, shows no detectable decomposition either during the drying procedure or during storage under nitrogen gas at -20 degrees C for several months. Using dry product prepared from fixed volumes of ethanolic solution, standardized solutions of known amounts of the highly purified and stored NADH can be obtained in a few seconds.