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At least 19 recordsLinked to original sources
PubMed1976

The regulation of rat liver tryptophan pyrrolase activity by reduced nicotinamide-adenine dinucleotide (phosphate). Experiments with glucose and nicotinamide.

1. Chronic administration of glucose or nicotinamide in drinking water inhibits the activity of rat liver tryptophan pyrrolase, and subsequent withdrawal causes an enhancement. The enzyme activity is also inhibited by administration in drinking water of sucrose, but not fructose, which is capable of preventing the glucose effect. 2. The inhibition by glucose or nictinamide is not due to a defective apoenzyme synthesis nor a decreased cofactor availability. 3. The inhibition by nicotinamide is reversed by regeneration of liver NAD+ and NADP+ in vivo by administration of fructose, pyruvate or phenazine methosulphate. Inhibition by glucose is also reversed by the above agents and by NH4Cl. Reversal of inhibition by glucose or nicotinamide is also achieved in vitro by addition of NAD+ or NADP+. 4. Glucose or nicotinamide increases liver [NADPH]. [NADP+] is also increased by nicotinamide. [NADPH] is also increased by sucrose, but not by fructose, which prevents the glucose effect. Phenazine methosulphate prevents the increase in [NADPH] caused by both glucose and nicotinamide. 5. It is suggested that the inhibition of tryptophan pyrrolase activity by glucose or nicotinamide is mediated by both NADPH and NADH.

Animals↗
PubMed1979

The fate of [14C]streptozotocin in nicotinamide-pretreated mice: observations on pancreatic islet radioactivity and urinary N1-methyl-14C]nicotinamide-excretion.

A high labelling of the pancreatic islets was found 3 and 24 h after a diabetogenic dose of [14C]streptozotocin to mice in which the acids islet injury had been prevented by nicotinamide-pretreatment. In non-pretreated [14C]streptozotocin-injected mice, a much lower radioactivity was observed in the pancreatic islets; at 3 h and at 24 h, there was no detectable radioactivity in the islets. No evidence was found to indicate that nicotinamide-pretreatment had any marked effect on the uptake or retention of radioactivity in other tissues. N1-[methyl-14C]nicotinamide was not found in the urine of non-pretreated [14C]streptozotocin-injected mice. When the animals were pretreated with nicotinamide, N1-[methyl-14C]nicotinamide was detected in the urine, but this represented only a small fraction of the injected radioactivity and of the excreted N1-methylnicotinamide. This result does not support the hypothesis that the disturbance of the NAD-metabolism, which streptozotocin causes, is due to a methylation of nicotinamide.

Animals↗
PubMed1979

Pyridine nucleotide cycle of Salmonella typhimurium: in vitro demonstration of nicotinamide mononucleotide deamidase and characterization of pnuA mutants defective in nicotinamide mononucleotide transport.

The enzyme nicotinamide mononucleotide deamidase, an integral component of the proposed four-membered pyridine nucleotide cycle (PNC IV), has been demonstrated in extracts of Salmonella typhimurium LT2. The enzyme has an optimum pH of 8.7 and deamidates nicotinamide mononucleotide, forming nicotinic acid mononucleotide. Sigmoidal kinetic data suggest that this enzyme may be allosteric and therefore an important regulatory component of pyridine nucleotide cycle metabolism. Mutants previously designated pncC in anticipation of their lacking nicotinamide mononucleotide deamidase were examined and found to have normal levels of this enzyme. [14C]nicotinamide mononucleotide uptake studies, however, revealed a defect in the transport of this compound. Accordingly, the genetic designation for this locus was changed to pnuA to reflect its involvement in pyridine nucleotide uptake. Evidence is presented for the existence of two separate nicotinamide mononucleotide transport systems.

Amidohydrolases↗
PubMedDate not supplied

[Content of nicotinamide coenzymes in rat liver under conditions of nicotinamide administration].

The content of NAD+, NADH, NADP+, NADPH in the liver of normal, fasting rats, those on the low-carbohydrate diet and suffering from alloxan diabetes was studied as affected by nictotinamide. Changes in the NAD+ content, sum of nicotinamide coenzymes, the [NAD+] + [NADP+]/[NADH] +/- [NADPH] and [NAD+] + [NADH] (sum of nicotinamide coenzymes) ratios are mainly due to nicotinamide administration. Changes in the content of reduced forms of both nucleotides depend equally on nicotinamide administration and the physiological state of animals. Response of the rat organism to nicotinamide administration consists in a sharp intensification of NAD+ synthesis and in a less pronounced intensification of NADH, NADP+ and NADPH synthesis.

Animals↗
PubMed1975

Nicotinamide 3,N4-ethenocytosine dinucleotide, an analog of nicotinamide adenine dinucleotide. Synthesis and enzyme studies.

A structural analog of NAD+, NICOTINAMIDE 3,N-4ethenocytosine dinucleotide (epsilonNCD+), has been synthesized, characterized, and compared in activity with the natural coenzyme in several enzyme systems. The Vmax and apparent Km values were determined for NAD+, epsilonNCD+, and epsilonNAD+ (nicotinamide 1, N6-ethenoadenine dinucleotide) with yeast alcohol, horse liver alcohol, pig heart malate, beef liver glutamate, and rabbit muscle lactate and glyceraldehyde-3-phosphate dehydrogenases. The Vmax for epsilonNCD+ was as great or greater than that obtained for NAD+ with three of the enzymes, 60-80 per cent with two others, and 14 percent with one. EpsilonNCD+ was found to be more active than epsilonNAD+ with all six dehydrogenases. EpsilonNCD+ served as a substrate for Neurospora crassa tnadase, but could not be phosphorylated with pigeon liver NAD+ kinase. NAD+ pyrophosphorylase from pig liver was unable to catalyze the formation of epsilonNCD+ from the triphosphate derivative of epsilon-cytidine and nicotinamide mononucleotide, but was able to slowly catalyze the pyrolytic cleavage of epsilonNCD+. The coenzyme activity of epsilonNCD+ with dehydrogenases can be discussed in terms of the close spatial homology of epsilonNCD+ and NAD+, which may allow similar accommodations within the enzyme binding regions.

Animals↗
PubMedDate not supplied

Growth of Mycoplasma synoviae in a medium supplemented with nicotinamide instead of B-nicotinamide adenine dinucleotide.

The cultivation of Mycoplasma synoviae (MS) on growth medium requires supplementation with B-nicotinamide adenine dinucleotide (NAD), an expensive and relatively unstable compound. Strains of MS were adapted (selected) to grow in a medium supplemented instead with nicotinamide, a stable and inexpensive substance that can be heat-sterilized in the medium without impairing its growth-promoting properties. MS plate agglutinating antigens grown in nicotinamide-enriched media were comparable in yield and serological reaction to antigens grown with NAD supplementation.

Antigens, Bacterial↗
PubMed1977

X-ray structures of two oxidation states of a flavin-nicotinamide biscoenzyme and models for flavin--nicotinamide interactions.

The flavin nicotinamide biscoenzymes Flox(-)--C3--Nic+ and H2Flred--C3--Nic+ assume extended conformations in the solid state. In both derivatives the nicotinamide and flavin groups associate through hydrogen bonding. The bending angle of the reduced flavin moiety is less than half that in any previously reported 1,5-dihydroflavin structure. This effect is apparently due to ring stacking interactions.

Chemical Phenomena↗
PubMed1979

Relationship between the ability of nicotinamide to maintain nicotinamide-adenine dinucleotide in rat liver cell culture and its effect on cytochrome P-450.

Rat hepatocytes cultured for 24 h lose 60% of their NAD content. Treatment with nicotinamide prevents the loss of NAD as well as the previously reported loss of cytochrome P-450, suggesting a possible causal relationship. However, isonicotinamide also prevents the loss of cytochrome P-450, but does not increase the concentration of NAD, demonstrating that the ability of nicotinamide to maintain cytochrome P-450 is not apparently related to its effect on the NAD content of cultured hepatocytes.

Animals↗
PubMed1975

Nicotinamide adenine dinucleotide levels in chick limb mesodermal cells in vitro: effects of 3-acetylpyridine and nicotinamide.

The studies reported here show that in cultures of developing mesodermal cells, chondrogenic expression is associated with a progressive decline in cellular NAD+ levels. Furthermore, reduced cellular NAD+ levels resulting from exposure to the nicotinamide analog 3-acetylpyridine are correlated with a 2- to 100-fold potentiation of chondrogenic expression. Conversely, elevated NAD+ levels resulting from exposure to nicotinamide alone are correlated with inhibition of chondrogenic expression. These data are consistent with the hypothesis that pyridine nucleotides, or some derivative thereof, play a central role in the control of muscle and cartilage development in embryonic chick limbs.

Animals↗
PubMed1977

Action of nucleotide phosphotransferase of Escherichia coli on nicotinamide riboside and nicotinamide mononucleotide.

The action of the nucleotide phosphotransferase of Escherichia coli on nicotinamide riboside and on its 5'-phosphate results in the addition of one phosphate moiety to each of the substrates. Although the proof is not conclusive, it is likely that the phosphate group is transferred to the 3'-hydroxyl of the ribose. This is in contrast to the behavior of the enzyme toward NAD in which only the adenylic acid portion is phosphorylated enzymically.

Chemical Phenomena↗
PubMed1976

Application of nicotinamide-adenine dinucleotide analogs for clinical enzymology: a spectrophotometric method for clinical analysis of lactate dehydrogenase patterns with the use of a nicotinamide-adenine dinucleotide analog.

The activities of porcine lactate dehydrogenase (LHD) isoenzymes were analyzed using nicotinamide-adenine dinucleotide (NAD) or its analogs as a cofactor, with varying concentrations of L-lactate from 13 to 530 mM. The greatest differences between H4-type and M4-type isoenzymes in reaction rates were observed when their activities were compared in a reaction mixture containing 530 mM lactate and NAD, and also in a system of 13 mM lactate with thionicotinamide-hypoxanthine dinucleotide as a cofactor. The ratio of the LDH activity exerted in the former reaction mixture to that exerted in the latter was termed the N/T value. The N/T values of porcine H4 and M4 isoenzymes were 0.49 and 9.33, respectively. The N/T values of other three isoenzymes (H3M1, H2M2 and H1M3) were calculated by assuming that the single subunits H1 and M1 contribute one-fourth of the values of 0.49 and 9.33, respectively, and a given isoenzyme which is a combination of four subunits of H and M comprises the sum of their values. The calculated values agreed fairly well with the experimental results. The N/T value method was found to be applicable to human LDH isoenzymes, and sera from various patients were analyzed in comparison with hormonal sera. The method is particularly suitable for the numerical expression of LDH isoenzyme profiles.

Animals↗
PubMed1976

Studies on the effects of coenzyme A-SH: acetyl coenzyme A, nicotinamide adenine dinucleotide: reduced nicotinamide adenine dinucleotide, and adenosine diphosphate: adenosine triphosphate ratios on the interconversion of active and inactive pyruvate dehydrogenase in isolated rat heart mitochondria.

The content of coenzyme A-SH (CoASH) and acetyl-CoA of suspensions of rat heart mitochondria was stabilized by the addition of DL-carnitine and acetyl-DL-carnitine, in the presence of the respiratory inhibitor rotenone. The mitochondrial content of NAD+ and NADH was similarly stabilized by the addition of acetoacetate and DL-3-hydroxybutyrate, and the content of ADP and ATP was imposed by the addition of these nucleotides to the mitochondrial suspension, in the presence of uncoupling agent and oligomycin, to inhibit ATPase. Under these conditions, mitochondrial CoASH/acetyl-CoA, NAD+/ NADH, and ADP/ATP ratios could be varied independently, and the effect on the interconversion of active and inactive pyruvate dehydrogenase could be studied. Decreases in both CoASH/acetyl-CoA and NAD+/NADH ratios were shown to be inhibitory to the steady state activity of pyruvate dehydrogenase, and this effect is described at three different ADP/ATP ratios and different concentrations of added MgCl2. A new steady state level of activity was achieved within 10 min of a change in either CoASH/acetyl-CoA or NAD+/NADH ratio; the rate of inactivation was much higher than the rate of reactivation under these conditions. Effects of CoASH/acetyl-CoA and NAD+/NADH may be additive but are still quantitatively lesser than the changes in activity of pyruvate dehydrogenase induced by changes in ADP/ATP ratio. The variation in activity of pyruvate dehydrogenase with ADP/ATP ratio is described in the absence of changes in the other two ratios, conditions which were not met in earlier studies which employed the oxidation of different substrates to generate changes in all three ratios.

Acetyl Coenzyme A↗
PubMedDate not supplied

Affinity chromatography of yeast nicotinamide-adenine dinucleotide-specific isocitrate dehydrogenase on immobilized nicotinamide-adenine dinucleotide. Effects of ligands.

The method of affinity chromatography has been used for studying the effects of some ligands of yeast NAD-specific isocitrate dehydrogenase on the affinity of the enzyme for NAD+ immobilized on Sepharose 4B. In absence of ligands, the enzyme is eluted from NAD+-Sepharose columns by 0.1 M phosphate buffer, pH 7.6, in a highly purified form. The elution of enzyme is accelerated by NAD+ and, more effectively, by AMP; and retarded by isocitrate and citrate. The elution patterns show a rather irregular shape, probably due to the occurrence of aggregation processes of the enzyme protein.

Adenosine Monophosphate↗
PubMedDate not supplied

[Effect of nicotinamide, adenosine and nicotinamide-adenine dinucleotide on the NAD and NAD.H2 content in the liver and brain of intact rats and in hypoxia].

Nicotine-amide (25 mg/kg) in the liver and adenosine (50 mg/kg) in the liver and brain of intact rats enhance the NAD+NAD'H2 content. These drugs when used in the same doses raise the NAD+NAD'H2 level in the organs reduced in hypoxia and their proportion only with the combined application of these drugs. NAD (30 mg/kg) increases the NAD+NAD'H2 concentration in the liver and brain of intact and in the liver of "hypoxic" rats. It appears that in the mechanism of the antihypoxic action of nicotine-amide, adenozine and NAD a definite part plays their action on the level of nicotine-amide co-enzymes.

Adenosine↗