Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.1.1.27 (lactate dehydrogenase)
29,211 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The reciprocity of effects of two ligands simultaneously bound to a protein as a ternary complex may be proven by measurements of four standard free energies of binding. Two of these are for the binding of each ligand in the absence of the other, and the other two for the binding of each ligand in the presence of saturating amounts of the other (conditional free energies). These four quantities have been measured for the complexes of oxalate and nicotinamide adenine dinucleotide with chick heart lactate dehydrogenase. The differences between conditional and unconditional free energies are: oxalate, -1.1 +/- 0.3 kcal; NADH,-1.3 +/- 0.2 kcal, thus proving the reciprocity within experimental error.
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PMID:Quantitative demonstration of the reciprocity of ligand effects in the ternary complex of chicken heart lactate dehydrogenase with nicotinamide adenine dinucleotide oxalate. 16 96

The effect of the weak polarity-reducing agent, ethylene glycol, on the binding of pig heart lactate dehydrogenase to N6-(6-aminohexyl)-AMP-Sepharose has been investigated. In the absence of the reagent and under the conditions used, a non-specific interaction of the enzyme with the adsorbent led to recoveries of enzyme activity as low as 60% when the enzyme was eluted from the columns with a linear NADH gradient. The inclusion of low concentrations of ethylene glycol in column irrigants considerably improved the recovery of enzyme activity with quantitative recoveries being obtained in the presence of 20-30%. Concentrations of ethylene glycol about 35% altered the native conformation of lactate dehydrogenase and led to a decreased affinity for the immobilised ligand. Under these conditions, the altered protein fluorescence and decreased ability to bind NADH could be correlated with the chromatographic behaviour of the enzyme on columns of N6-(6-aminohexyl)-AMP-Sepharose. These effects were exploited to elute the enzyme from a column of immobilised-AMP with a linear gradient of ethylene glycol.
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PMID:Biospecific affinity chromatography in aqueous-organic cosolvent mixtures. The effect of ethylene glycol on the binding of lactate dehydrogenase to an immobilised-AMP analogue. 17 86

Alkylation at N-1 of the NAD+ adenine ring with 3,4-epoxybutanoic acid, followed by chemical reduction to the alkali-stable NADH form and alkaline Dimroth rearrangement, gave the NADH derivative alkylated at the exocyclic adenine amino group. Enzymic reoxidation of the latter derivative gave nicotinamide-6-(2-hydroxy-3-carboxypropylamino)purine dinucleotide, a functionalized NAD+ analogue carrying an omega-carboxyalkyl side-chain at the exocyclic adenine amino group. Carbodiimide coupling of the latter derivative to high-molecular-weight water-soluble (polyethyleneimine, polylysine) and insoluble (aminohexyl-Sepharose) polymers gave the corresponding macromolecularized NAD+ analogues. These derivatives have been shown to be enzymically reducible. The polyethyleneimine and polylysine analogues showed a substantial degree of efficiency relative to free NAD+ with rabbit muscle lactate dehydrogenase (60 and 25% respectively) but a lower one with yeast alcohol dehydrogenase and Bacillus subtilis alanine dehydrogenase (2-7%). The polyethyleneimine derivative entrapped in cellulose triacetate fibres together with the lactate dehydrogenase was operationally stable during repetitive use.
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PMID:Synthesis of coenzymically active soluble and insoluble macromolecularized NAD+ derivatives. 17 91

The dicarboxylate radical -OOC--CH--CH(OH)COO- was generated in an N2O-saturated fumarate solution by high energy ionizing radiation. When NADH was present in the solution, product analysis indicated a stoichiometry of 2 molecules of the radical reacted with 1 NADH molecule to form 2 malate and 1 enzymatically active NAD+ molecules. In a similar experiment using tritium label on position A of NADH, due to an isotope effect, only 10% of the label was transferred to malate; most of the remaining tritium was found in the NAD+ formed. When lactate dehydrogenase was added, however, no la bel was detectable in NAD+, and over 80% of the tritium lost from NADH was found in malate. The stereospecific transfer of the hydrogen atom from lactate dehydrogenase-bound NADH to the dicarboxylate radical suggested that the free radical reaction must have taken place at the active site. The hydrogen atom transfer was inhibited by oxamate. Results from flow experiments in which an irradiated fumarate solution was mixed with a solutionof lactate dehydrogenase and NADH are in support of a mechanism in which the hydrogen atom transfer occurs in the first oxidation step.
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PMID:Lactate dehydrogenase-catalyzed stereospecific hydrogen atom transfer from reduced nicotinamide adenine dinucleotide to dicarboxylate radicals. 17 Feb 58

31P nuclear magnetic resonance spectra of the pyrophosphate group in NAD+ and NADH were recorded in the presence of beef heart lactate dehydrogenase and rabbit muscle glyceraldehyde-3-phosphate dehydrogenase. At high lactate dehydrogenase concentrations (60 mg/ml), two NADH resonances are observed: a slowly exchanging peak which is shifted to 1.9 ppm downfield (relative to free NADH) and a rapidly exchanging peak with a downfield shift of 0.5-0.6 ppm. At lover concentrations (15 mg/ml) only the rapidly exchanging peak is observed thus indicating that the peak observed at-1.9 ppm is due to coenzyme bound to an aggregated enzyme species. With NAD+, rapid exchange and downfield shifts are observed at both enzyme and concentrations, with shifts of about 1.5 ppm and 0.6 ppm at 60 and 15 mg/ml, respectively. In the presence of glyceraldehydephosphate dehydrogenase, the results are independent of enzyme concentration, and slow exchange and upfield shifts of 0.4-0.6 ppm occur with each coenzyme. These data indicate that the environment of the pyrophosphate group of oxidized and reduced coenzyme is the same for a given dehydrogenase, but is different in one enzyme from the other. The resonances observed with glyceraldehydephosphate dehydrogenase are broader than those observed with lactate dehydrogenase. This is indicative of either shorter relaxation times with the former enzyme, or the presence of multiple, unresolved resonances.
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PMID:31 P nuclear magnetic resonance studies of the interaction of pyridine nucleotide coenzymes with dehydrogenases. 17 Sep 65

Biopsies from vastus lateralis muscle of male patients suffering from chronic ethanol abuse were studied with regard to histochemical reactions of ATPase and NADH-diaphorase; enzymatic activities of triosephosphate dehydrogenase (TPD), lactate dehydrogenase (LD), and cytochrome c oxidase (cytox); content of ATP, creatine phosphate, and glycogen; and volume fractions of fat, mitochondria, and fibrillar and extrafibrillar space. The results were compared with those from controls without known abuse of ethanol. The relative numbers of fibers were the same in two groups, but the size of the fast-twitch-glycolytic (white) fibers was diminished in the alcoholic group. The activities of TPD and LD were diminished in skeletal muscle of the alcoholics. This is most probably caused by the reduced amount of fast-twitch-glycolytic tissue, as there was a good correlation between this amount and the activity of the two enzymes. The activity of cytox was slightly lower in muscle of the alcoholics than in that of the controls. The volume fraction of mitochondria was lower in the alcoholic group than in the control group. Volume fractions of fat and fibrillar and extrafibrillar space were equal in the two groups. No significant differences were found in the amount of glycogen and ATP in the muscle of the two groups. However, the content of creatine phosphate is higher in the alcoholic group than in the control group.
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PMID:Effects of chronic ethanol abuse on structure and enzyme activities of skeletal muscle in man. 17 13

1. A new and rapid continuous assay of rat liver microsomal UDP-glucuronyltransferase (EC 2.4.1.17) has been developed. It is based on measurement of UDP production from UDP-glucuronate during the glucuronidation reaction; UDP production was continuously measured by coupling it to the conversion of NADH into NAD+ through pyruvate kinase and lactate dehydrogenase. This assay is independent of the acceptor substrate used; several findings confirm its applicability. 2. The glucuronidation rate of a series of phenol derivatives was determined with this assay, by using a Triton X-100-activated microsomal preparation as enzyme source. Conjugation of a series of nitrophenol derivatives was also investigated by the 'classical' assay (measurement of disappearance of the yellow colour of the nitrophenol during glucuronidation). The substrate with the highest conversion rate was 3-methyl-2-nitrophenol. 3. Both electron releasing and electron withdrawing ring substituents increased the glucuronidation rate of the phenol derivatives, as compared with phenol. 4. Lipid solubility seems important for determining the conversion rate: poorly lipid-soluble substrates were glucuronidated only at a low rate and high lipid solubility seems to be a prerequisite for high conversion rate. Glucuronidation of poorly lipid-soluble compounds may be limited by diffusion. 5. The consequences of these findings for the interpretation of studies on heterogeneity of the enzyme are discussed.
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PMID:A rapid NAD+-linked assay for microsomal uridine diphosphate glucuronyltransferase of rat liver and some observations on substrate specificity of the enzyme. 17 50

Pig heart lactate dehydrogenase (L-lactate: NAD+ oxidoreductase, EC 1.1.1.27) was partially inactivated by reaction with phenylmaleimide. The resulting protein mixture was separated by affinity chromatography on a Sepharose-linked oxamate column yielding three distinct enzyme fractions with one, two and three out of four subunits being modified. The specific activities of these samples were lower than expected from the degree of modification, while the maximum binding capacity of NADH-oxamate related well to the number of catalytic centers modified. A possible cooperative effect in the native enzyme is discussed.
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PMID:The separation of partially modified lactate dehydrogenase by affinity chromatography. The specific activity of protomers? 17 37

A new NAD -isomer was prepared, in which the D-ribose of the adenosine moiety was substituted by the enantiomeric L-ribose. As compared to nicotinamide-adenine-dinucleotide (NAD) and NADH the coenzyme isomer (D,L)-NAD and its dihydroform (D,L)-NADH are far less tightly bound to lactate dehydrogenase and alcohol dehydrogenase from horse liver. In the presence of the second substrate (D,L)-NAD and (D,L)-NADH act as hydrogen acceptor and hydrogen donator, respectively, with lactate dehydrogenase and alcohol dehydrogenases from horse liver and yeast. Compared to NAD and NADH the Michaelis constants are always increased, the catalytic constants (V/Et) were found to be decreased except for the dihydroform reacting with alcohol dehydrogenase from liver.
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PMID:Interaction between dehydrogenases and a new NAD -isomer. 17 98

Dogfish M4 lactate dehydrogenase, like the corresponding pig enzyme, is inactivated by pyridoxal 5'-phosphate through modification of a single essential lysine residue. The activity is completely protected in the complexes E-NAD+-oxalate, E-NADH-oxamate and E-(NAD+-pyruvate adduct), but only partially protected in E-NAD+, E-NADH, E-NAD+-oxamate and E-NADH-oxalate.
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PMID:Dogfish M4 lactate dehydrogenase: reversible inactivation by pyridoxal 5'-phosphate and complete protection in complexes that mimic the active ternary complex. 17 80


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