Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: DrugBank:EXPT02288 (NADH)
 21,914 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Addition of ubiquinone-1 to E. coli ML 308-225 membrane vesicles dramatically increases coupling between NADH oxidation and active transport such that initial rates and steady-state levels of lactose and amino-acid accumulation are comparable to those observed during D-lactate oxidation. Similar but less dramatic effects are observed with the quinone and succinate or L-lactate. In the presence of NADH and ubiquinone-1, the vesicles also generate a membrane potential (interior negative) that is similar in magnitude to that observed in the presence of D-lactate. Stimulation of NADH-dependent transport by ubiquinone-1 cannot be accounted for by increased rates of oxidation of NADH, and the effect of the quinone on NADH-dependent lactose transport is not observed in vesicles depleted of NADH dehydrogenase activity. Thus, it is apparent that ubiquinone-1 shunts electrons from NADH dehydrogenase [NADH:(acceptor)oxidoreductase; EC 1.6.99.3] to the portion of the respiratory chain containing the energy-coupling site. The findings demonstrate unequivocally that inefficient coupling of NADH oxidation to active transport cannot be due to the presence of inverted vesicles. In addition, they provide further support for specific localization of the energy-coupling site.
 ...
PMID:Ubiquinone-mediated coupling of NADH dehydrogenase to active transport in membrane vesicles from Escherichia coli. 0 Jun 72

The L-(+)-lactate dehydrogenase (L-lactate:NAD+ oxidoreductase, EC 1.1.1.27) of Streptococcus lactis C10, like that of other streptococci, was activated by fructose 1,6-diphosphate (FDP). The enzyme showed some activity in the absence of FDP, with a pH optimum of 8.2; FDP decreased the Km for both pyruvate and reduced nicotinamide adenine dinucleotide (NADH) and shifted the pH optimum to 6.9. Enzyme activity showed a hyperbolic response to both NADH and pyruvate in all the buffers tried except phosphate buffer, in which the response to increasing NADH was sigmoidal. The FDP concentration required for half-maximal velocity (FDP0.5V) was markedly influenced by the nature of the assay buffer used. Thus the FDP0.5V was 0.002 mM in 90 mM triethanolamine buffer, 0.2 mM in 90 mM tris(hydroxymethyl)aminomethanemaleate buffer, and 4.4 mM in 90 mM phosphate buffer. Phosphate inhibition of FDP binding is not a general property of streptococcal lactate dehydrogenase, since the FDP0.5V value for S. faecalis 8043 lactate dehydrogenase was not increased by phosphate. The S. faecalis and S. lactis lactate dehydrogenases also differed in that Mn2+ enhanced FDP binding in S. faecalis but had no effect on the S. lactis dehydrogenase. The FDP concentration (12 to 15 mM) found in S. lactis cells during logarithmic growth on a high-carbohydrate (3% lactose) medium would be adequate to give almost complete activation of the lactate dehydrogenase even if the high FDP0.5V value found in 90 mM phosphate were similar to the FDP requirement in vivo.
 ...
PMID:Fructose 1,6-diphosphate-activated L-lactate dehydrogenase from Streptococcus lactis: kinetic properties and factors affecting activation. 1 95

The rates of reduction of seven redox dyes by 13 bacterial strains were measured and found to vary greatly between different bacterium/dye combinations. Phenazine ethosulphate and toluidine blue were the most rapidly reduced dyes by the majority of bacteria and resorufin and 2-hydroxy-1,4-naphthoquinone were reduced slowly, if at all. There was also considerable variation in the rates of reduction with any single dye/organism combination. Glucose stimulated the rates of endogenous dye reduction in about half of the organisms. For Bacillus cereus, Pseudomonas fluorescens and Escherichia coli, dye reduction was stimulated by a range of exogenous substrates but lactose, the primary available carbon and energy source in milk, had little effect. In Lactococcus lactis, dye reduction was stimulated by sugars but not by organic acids. Oxygen successfully competed with dye reduction in organisms containing respiratory chains, but with membrane fractions, dye reduction was more rapid than oxygen consumption. All the organisms showed little cytosolic dye reduction, except L. lactis which showed substantial rates of reduction of some dyes by this fraction. With the membrane fraction of E. coli and Ps. fluorescens, cyanide inhibited NADH and succinate-dependent dye reduction, Antimycin A inhibited lactate and succinate and rotenone had no significant effect, but inhibition was not always observed with membrane from both organisms.
 ...
PMID:An investigation of dye reduction by food-borne bacteria. 164 3

Sensitive bioluminescent methods were developed to measure the metabolites glucose, glucose 6-phosphate (G6P), glucose 1-phosphate (G1P), UDP-glucose, and UDP-galactose in human milk and lactose and galactose in human plasma. The bioluminescent methods measured NADH produced by coupled enzymatic assays derived from equivalent spectrophotometric methods. We found that the long chain fatty acids in human milk (C10-C16) inhibited the bioluminescent reactions. This inhibition was overcome by adding defatted bovine serum albumin to the reaction mixture containing the bioluminescent enzymes. It also was necessary to modify methods of deproteinizing milk and blood plasma to accommodate small sample volumes. In the development of these assays emphasis was given to simplicity of reagent preparation, minimizing cost, and ease of use. The detection limit for the bioluminescent method for NADH was 0.28 nM for a 20-microliters sample. For the assays of the metabolites, recoveries ranged from 91 to 107%. For sample sizes of 2 to 5 microliters of protein free sample, the detection limits for milk were G1P, 0.09 microM; G6P, 0.05 microM; UDPhexose, 0.07 microM; UDP-Glc, 0.03 microM; glucose, 9 microM; and for plasma, lactose, 0.76 microM, galactose, 0.31 microM. The bioluminescent methods gave equivalent results to spectrophotometric methods for the measurement of blood lactose and milk glucose.
 ...
PMID:Microanalysis of the metabolic intermediates of lactose synthesis in human milk and plasma using bioluminescent methods. 274 36

The effluent from a chromatographic column was mixed with nicotinamide adenine dinucleotide coenzyme (NAD+) buffer and passed through a packed-bed reactor containing immobilized glucose dehydrogenase. Oxidation of the carbohydrates emerging from the column produced an equivalent amount of reduced coenzyme (NADH), which was detected electrochemically using an electrode modified with 7-dimethylamino-1,2-benzophenoxazine (Meldola Blue). Separation was effected in three different chromatographic systems containing a protonated ion exchanger, a calcium(II)-saturated or a lead(II)-saturated ligand exchange column. Separation, detection and k' values are reported for glucose, 2-deoxyglucose, xylose, mannose, cellobiose, lactose, ribose and glucosamine. The detection limit was 2 ng for a 20-microliter injection of glucose and the response was linear up to 6300 ng. Samples from fermentation of penicillin were analysed for lactose and glucose with the described detector. A comparison with the recordings from a refractive index detector showed that the selectivity of the enzymes and the modified electrodes are necessary for the determination of glucose and lactose.
 ...
PMID:High-performance liquid chromatographic separation of some mono- and disaccharides with detection by a post-column enzyme reactor and a chemically modified electrode. 342 19

1. The growth of the lactoperoxidase-sensitive Streptococcus cremoris 972 in a synthetic medium was inhibited by lactoperoxidase and thiocyanate. The glycolysis and oxygen uptake of suspensions of Strep. cremoris 972 in glucose or lactose were also inhibited. The lactoperoxidase-resistant Strep. cremoris 803 was not inhibited under these conditions but was inhibited in the absence of a source of energy. 2. Lactoperoxidase (EC 1.11.1.7), thiocyanate and hydrogen peroxide completely inhibited the hexokinases of non-metabolizing suspensions of both strains. The inhibition was reversible, hexokinase and glycolytic activities of Strep. cremoris 972 being restored by washing the cells free from inhibitor. The aldolase and 6-phosphogluconate-dehydrogenase activities of Strep. cremoris 972 were partially inhibited but several other enzymes were unaffected. 3. The resistance of Strep. cremoris 803 to inhibition was not due to the lack of hydrogen peroxide formation, to the destruction of peroxide, to the inactivation of lactoperoxidase or to the operation of alternative pathways of carbohydrate metabolism. 4. A ;reversal factor', which was partially purified from extracts of Strep. cremoris 803, reversed the inhibition of glycolysis of Strep. cremoris 972. The ;reversal factor' also catalysed the oxidation of NADH(2) in the presence of an intermediate oxidation product of thiocyanate and was therefore termed the NADH(2)-oxidizing enzyme. 5. The NADH(2)-oxidizing enzyme was present in lactoperoxidase-resistant streptococci but was absent from lactoperoxidase-sensitive streptococci.
 ...
PMID:The inhibition of streptococci by lactoperoxidase, thiocyanate and hydrogen peroxide. The effect of the inhibitory system on susceptible and resistant strains of group N streptococci. 429 Sep 83

Two classes of mutants isolated from E. coli and Salmonella typhimurium are altered in respiration-coupled active transport, as studied in whole cells and/or isolated membrane vesicles. Mutant cells defective in D-lactate dehydrogenase (dld) transport amino acids and lactose normally. Membrane vesicles prepared from these mutants do not exhibit D-lactate-dependent transport, D-lactate oxidation, or D-lactate: dichlorophenolindophenol reductase activity. However, succinate-dependent transport is markedly enhanced in these mutants, without a corresponding increase in succinic dehydrogenase activity. The second class of mutants is defective in the coupling of electron transfer to active transport. Whole cells and membrane vesicles prepared from these etc mutants exhibit markedly reduced ability to transport amino acids, despite the ability of the vesicles to oxidize D-lactate, succinate, and NADH. Vectorial phosphorylation of alpha-methylglucoside by these mutants is normal. Electrontransfer coupling mutants are similar phenotypically to mutants uncoupled for oxidative phosphorylation (uncA), but have normal ATPase activity. Moreover, uncA mutants catalyze active transport as well as does the wild type. These experiments indicate that the ETC component is essential for the coupling of respiratory energy to active transport, and provide further evidence that the generation or utilization of ATP is not involved in these transport mechanisms.
 ...
PMID:Mutants of Salmonella typhimurium and Escherichia coli pleiotropically defective in active transport. 434 63

A fluorometric procedure for quantitating the amount of N-acetylneuraminic acid enzymatically released by the neuraminidase activity from N-acetylneuraminyl-lactose (sialyl-lactose) has been developed. The liberated lactose is hydrolyzed with beta-galactosidase, and the released galactose is oxidized with galactose dehydrogenase and NAD+; finally, the NADH produced is measured by fluorometry (excitation at 340 nm and analysis of emitted light at 465 nm). The fluorometric assay is about 10-fold more sensitive than the spectrophotometric procedure that measures NADH at 340 nm. It readily measures amounts as little as 2 nmol of sialic acid, and does not require the use of radioactive isotopes. Interferences due to sucrose or other substances, which cause errors in some cases with the use of the periodate-thiobarbiturate method for neuraminidase activity determination, are avoided. The procedure reported here provides a sensitive, rapid, and relatively simple method (feasible with commercialized reagents) for measuring the neuraminidase activity not only in purified samples from different sources but also directly in biological materials such as viruses. The technique has been tested with some viruses recently isolated belonging to Orthomyxoviridae or Paramyxoviridae families, known to be rich in neuraminidase. Reciprocally, this method can also be employed for determining the sialic acid concentration in acylneuraminyl-lactose-containing compounds when using purified neuraminidase for hydrolysis.
 ...
PMID:A fluorometric procedure for measuring the neuraminidase activity: its application to the determination of this activity in influenza and parainfluenza viruses. 631 Oct 45

Nongrowing cells of Streptococcus lactis in a pH-stat were dosed with sugar to allow fermentation at the maximum rate or were fed a continuous supply of sugar at rates less than the maximum. Under anaerobic conditions, rapid fermentation of either glucose or lactose was essentially homolactic. However, with strain ML3, limiting the fermentation rate diverted approximately half of the pyruvate to formate, acetate, and ethanol. At limiting glucose fermentation rates, cells contained lower concentrations of lactate dehydrogenase activator (fructose 1,6-diphosphate) and pyruvate formate-lyase inhibitors (triose phosphates). As a result, pyruvate formate-lyase and pyruvate dehydrogenase play a greater role in pyruvate metabolism. In contrast to strain ML3, strain ML8 did not give the same diversion of products under anaerobic conditions, and cells retained higher concentrations of the above effector compounds. Lactose metabolism under aerobic conditions resulted in pyruvate excretion by both S. lactis ML3 and ML8. At 7% of the maximum utilization rate, pyruvate accounted for 69 and 35% of the lactose metabolized by ML3 and ML8, respectively. Acetate was also a major product, especially with ML8. The data suggest that NADH oxidase is involved in coenzyme recycling in the presence of oxygen and that pyruvate formate-lyase is inactivated, but the pyruvate dehydrogenase complex still functions.
 ...
PMID:Regulation of product formation during glucose or lactose limitation in nongrowing cells of Streptococcus lactis. 643 21

A new procedure for a sialidase assay, by bioluminescence, has been developed. The substrate, N- acetylneuraminyllactose (sialyllactose), hydrolysed by the sialidase activity, releases lactose. This lactose is hydrolysed with beta-galactosidase. The released galactose is oxidized with galactose dehydrogenase and NAD. The NADH produced in the last step is measured by a luminescence system, coupling two enzymes, NAD(P)H dehydrogenase (FMN) and luciferase. This microassay, which is specific, rapid, simple and ultra-sensitive, is a measure for amounts as little as (at least) 5 pmol of N-acetylneuraminic acid (corresponding to 0.15 ng of the released sialic acid). It uses commercialized reagents (non-radioisotopic) and avoids interferences common in other procedures. This method has been used for measuring sialidase activity directly on intact virus, avoiding inconvenient modifications produced in the extraction of the enzyme. The specific activity of sialidase of influenza virus X31 (H3N2), determined by this procedure, is 0.65 U/mg of total virus protein.
 ...
PMID:Sialidase assay by luminescence in the low picomole-range of sialic acid. Its application to the measurement of this activity in influenza virus. 673 52


1 2 3 4 5 Next >>