Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The binding of nicotinamide adenine dinucleotide (NAD+) to yeast glyceraldehyde-3-phosphate dehydrogenase (GPDH) has been studied at pH 6.5 and 8.5, at 5,25, and 40 degrees C, by calorimetry, fluorometry, spectrophotometry, equilibrium dialysis, and flow dialysis. As reported earlier for pH 7.3 (Velick S.F., Baggott, J.P., and Sturtevant, J.M. (1971), Biochemistry 10, 779), the binding is accompanied by enthalpy changes which become rapidly more negative as the temperature increases, with delta Cp = -500 to -750 cal deg-1 (mole of NAD+ bound)-1, and by entropy changes which also, as required by the large negative delta Cp, become rapidly more negative with increasing temperature. The binding data at pH 6.5 can be fitted on the basis of either four identical noninteracting sites, or of four sites showing a small degree of negative cooperativity. The data at pH 8.5, particularly at 40 degrees C, require the introduction of positive cooperativity, as was previously shown by Kirschner et al. (Kirschner, K., Eigen, M., Bittman, R., and Voigt, B. (1966), Proc. Natl. Acad. Sci. U.S.A. 56, 1661), and can be equally well fitted on the basis of a sequential model (Adair, G.S. (1925), J. Biol. Chem. 63, 529) or a concerted model (Monod, J., Wyman, J., and Changeux, J.P. (1965), J. Mol. Biol. 12, 88). It is proposed that the observed thermodynamic changes are largely the result of a hydrophobic effect due to a decrease in the exposure of nonpolar groups to the solvent, and of a tightening of the protein structure when the coenzyme is bound with concomitant decrease in the number of easily excitable internal degrees of freedom.
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PMID:Energetics of the cooperative and noncooperative binding of nicotinamide adenine dinucleotide to yeast glyceraldehyde-3-phosphate dehydrogenase at pH 6.5 and pH 8.5. Equilibrium and calorimetric analysis over a range of temperature. 1 17

Specific activity of 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) was measured in 48 tissue specimens of human female breast cancer and, in addition, 48 nonmalignant tissue specimens obtained in each case from the same cancer-bearing breast. In all cases the nonmalignant tissue showed greater conversion of estradiol-17 beta into estrone than the neoplastic tissues. In normal human breast tissue of premenopausal women specific enzyme activity depended on the phase of the MENSTRUAL CYCLE: the highest values of 17 beta-HSD activity were found in the early secretory phase. To determine the intracellular distribution of the 17 beta-HSD, purified microsomes, mitochondria, peroxysomes, lysosomes, nuclei and cytosol fractions were prepared. The purity of each fraction was monitored by marker enzymes. It was found that the 17 beta-HSD was mainly located in mitochondria and microsomes. Furthermore it could be demonstrated that the microsomal enzyme was bound tightly to the membranes of the endoplasmic reticulum, while the mitochondrial 17 beta-HSD was mainly associated with the outer membranes of the organelle. Kinetic parameters (Km-values, coenzyme requirements and maximal velocities) of a cytoplasmic, nuclear, mitochondrial and microsomal 17 beta-HSD of normal and neoplastic human mammary tissue were compared. Maximal velocity was highest in enzyme preparations of normal mammary tissue obtained from premenopausal women in the early secretory phase. Km-values wrere nearly identical in normal and neoplastic mammary tissue preparations (approx. 1 X 10(-6) M). NAD was more efficient than NADP as a cofactor. For the conversion of estradiol to estrone the optimum temperature was approximately 40 degrees C and the optimum pH 9.5. For the reduction of estrone the optimum pH was 6.5. Sulphydryl groups were shown to be essential for catalysis.
Mol Cell Endocrinol 1977 Feb
PMID:Comparison of the in vitro conversion of estradiol-17 beta to estrone of normal and neoplastic human breast tissue. 1 41

3-Aminopyridine mononucleotide, a nicotinamide mononucleotide analog, was prepared by enzymatic cleavage of 3-aminopyridine adenine dinucleotide by a snake venom phosphodiesterase and isolated by means of ion exchange chromatography. The spectrophotometric and fluorometric properties of this analog were studied. Several anions were shown to quench the fluorescence intensity of this analog. pH was shown to have a pronounced effect on the fluorescence intensity. 3-Aminopyridine mononucleotide was shown to be a coenzyme-competitive inhibitor of yeast alcohol dehydrogenase. The 3-aminopyridine mononucleotide was diazotized with the use of nitrous acid. A time dependent irreversible inactivation of yeast alcohol dehydrogenase resulted from incubation with the diazotized 3-aminopyridine mononucleotide at pH 7.0. Incubation of the enzyme with NAD prior to the addition of the diazotized 3-aminopyridine mononucleotid protected the enzyme against inactivation.
Mol Cell Biochem 1977 Mar 21
PMID:Studies of yeast alcohol dehydrogenase with 3-aminopyridine monucleotide. 1 65

We have studied the isocitrate dehydrogenase of Tetrahymena pyriformis. This enzyme is able to utilize both NAD and NADP, but kinetic studies suggest that the enzymatic activity with NAD is not of physiological signifance. Some of the factors that might regualte the NADP-dependent isocitrate dehydrogenase were also studied. This enzyme has an absolute requirement for divalent cations; Mg,+ and Mn2+ will serve as cofactors but the latter is more effective than the former. It is known that this enzyme is subject to a concerted inhibition by oxaloacetate and glyoxylate. Either glyoxylate or oxaloacetate alone also are capable of inhibiting the enzyme although higher concentrations are required. We have found concerted inhibition also for the NAD-dependent isocitrate dehydrogenase from rat liver and yeast. The activity of the Tetrahymena pyriformis enzyme is inhibited by NADPH. This inhibition is competitive with NADP. The Ki and Km values are, respectively, 20 micrometers and 18 micrometers.
Mol Cell Biochem 1977 Oct 07
PMID:Isocitrate dehydrogenase of Tetrahymena pyriformis. 2 34

NAD(P)H: FMN oxidoreductase (flavin reductase) couples in vitro to bacterial luciferase. This reductase, which is also postulated to supply reduced flavin mononucleotide in vivo as a substrate for the bioluminescent reaction, has been partially purified and characterized from two species of luminous bacterial. From Photobacterium fischeri the enzyme has a M. W. determined by Sephadex gel filtration, of 43,000 and may have a subunit structure. The turnover number at 20 degrees C, based on a purity estimate of 20 percent, is 1.7 times 10-4 moles of NADH oxidized per min per mole of reductase. The reductase isolated from Beneckea harveyi has an apparent molecular weight of 23,000; its purity was too low to permit estimation of specific activity. Using a spectrophotometric assay at 340 nm with the P. fischeri reductase, both NADH (Km, 8 times 10-5 M) and NADPH (Km, 4 times 10-4 M) were enzymatically oxidized, the Vmax with NADH being approximately twice that of NADPH. Of the flavins tested in this assay, only FMN (Km, 7.3 times 10-5 M) and FAD (Km, 1.4 times 10-4 M) were effective, FMN having a Vmax three times that of FAD. In the coupled assay, i.e., measuring the bioluminescence intensity of the reaction with added luciferase, the optimum FMN concentration was nearly 100 times less than in the spectrophotometric assay. The studies reported suggest the existence of a functional reductase-luciferase complex.
Mol Cell Biochem 1975 Jan 31
PMID:Flavin mononucleotide reductase of luminous bacteria. 4 4

The cell-free extract from blue-green alga Anacystis nidulans contains enzymatic activities which repair in vitro transforming DNA of bacteriophage T4 damaged by UV light or X-rays. The repair effect of the extract was observed with double-stranded irradiated DNA but not with denatured irradiated DNA. The level of restoration of the transforming activity depends on the protein concentration in the reaction mixture and on the dose of irradiation. A fraction of DNA lesions induced by X-rays is repaired by a NAD-dependent polynucleotide ligase present in the extract. The repair of UV-induced lesions is the most efficient in the presence of magnesium ions, NAD, ATP and the four deoxynucleoside triphosphates. The results indicate that the repair of UV-irradiated DNA is performed with the participation of DNA polymerase and polynucleotide ligase which function in the cell-free extract of the algae on the background of a low deoxyribonuclease activity.
Mol Biol Rep 1975 Jul
PMID:In vitro repair of UV-or x-irradiated bacteriophage T4 DNA by extract from blue-green alga Anacystis nidulans. 16 64

Flounder muscle (Pseudopleuronectes americanus) glyceraldehyde-3-phosphate dehydrogenase was characterized as to its stability towards various inactivating treatments in the presence and absence of the enzyme cofactor, NAD. Incubation of a partially purified enzyme preparation at urea concentrations greater than 2 M produced a very rapid inactivation. NAD greatly reduced the rate of inactivation at all the urea concentrations tested. Incubation of each of the three major muscle enzyme forms in 0.1 percent trypsin or chymotrypsin for forty-five minutes decreased the activity of each form by 65 percent and 55 percent, respectively. NAD (5mM) afforded complete protection to each enzyme form from proteolytic digestion by these two enzymes. Exposure of each form to 50 degrees or 20 mM ATP also led to gross inactivation which could be greatly reduced if the respective incubations were performed in the presence of 5mM NAD. NAD was also found to be required for the renaturation of the unfolded urea-denatured subunits to form the active tetramer.
Mol Cell Biochem 1975 Sep 30
PMID:Effect of NAD on flounder muscle glyceraldehyde 3-phosphate dehydrogenase. 17 55

A mutation leading to partial loss of NAD-linked ("catabolic') glutamate dehydrogenase does not affect the regulation of ammonium-repressible activities in Aspergillus nidulans. This mutation has been used to show that NAD-linked glutamate dehydrogenase does not normally participate in ammonium assimilation. A mutation leading to loss of NADP-linked ("anabolic') glutamate dehydrogenase has been used to show that NADP-linked glutamate dehydrogenase is not normally involved in glutamate catabolism. Strains defective in either enzyme are useful for determining which amino acids are metabolised via transamination to yield glutamate rather than via deamination to yield ammonium.
Mol Gen Genet 1975
PMID:A mutant of Aspergillus nidulans defective in NAD-linked glutamate dehydrogenase. 17 77

An investigation was made of changes in subunit interactions in glyceraldehyde 3-phosphate dehydrogenase on binding NAD+, NADH and other substrates by using the previously developed method of measurement of rates and extent of subunit exchange between the rabbit enzyme (R4), yeast enzyme (Y4) and rabbit-yeast hybrid (R2Y2) [Osborne & Hollaway (1974) Biochem. J. 143, 651-662]. The free energy of activation for the conversion of tetramer into dimer for the rabbit enzyme (R4 leads to 2R2) is increased by at least 12kJ/mol in the presence of NAD+. This increase is interpreted in terms of an NAD+-induced 'tightening' of the tetrameric structure probably involving increased interaction at the subunit interfaces across the QR plane of the molecule [see Buehner et al. (1974) J. Mol. Biol. 82, 563-585]. This tightening of the structure only occurs on binding the third NAD+ molecule to a given enzyme molecule. Conversely, binding of NADH causes a decrease in the free energy of activation for the R4 leads to 2R2 and Y4 leads to 2Y2 conversions by at least 10kJ/mol. This is interpreted as a NADH-induced 'loosening' of the structures arising from decreased interactions across the subunit interfaces involving the QR dissociation plane. In the presence of NADH the increase in the rate of subunit exchange is such that it is not possible to separate the hybrid from the other species if electrophoresis is carried out with NADH in the separation media. In the presence of a mixture of NADH and NAD+ the effect of NAD+ on subunit exchange is dominant. The results are discussed in terms of the known co-operativty between binding sites in glyceraldehyde 3-phosphate dehydrogenases.
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PMID:The investigation of substrate-induced changes in subunit interactions in glyceraldehyde 3-phosphate dehydrogenases by measurement of the kinetics and thermodynamics of subunit exchange. 17 55

Using NAD analogues as ligands, the structural requirements for negative cooperativity in binding to rabbit muscle glyceraldehyde-3-phosphate dehydrogenase were examined. Although the affinity of nicotinamide hypoxanthine dinucleotide is considerably lower than that of NAD+, it also binds to the enzyme with negative cooperatively. Two pairs of nicotinamide hypoxanthine dinucleotide binding sitess were distinguished, one pair having an affinity for the analogue which is 15 times that of the second pair. Negative cooperativity is also found in the Km values for the analogue. Thus modification of the adenine ring of NAD+ to hypoxanthine does not abolish negative cooperativity in coenzyme binding. Adenosine diphosphoribose binding to the same enzyme shows neither positive nor negative cooperativity, indicating that cooperativity apparently requires an intact nicotinamide ring in the coenzyme structure, under the conditions of these experiments. Occupancy of the nicotinamide subsite of the coenzyme binding site is not necessary for half-of-sites reactivity of alkylating or acylating compounds (Levitzki, A. (1974), J. Mol, Biol. 90, 451-458). However, it can be important in the negative cooperativity in ligand binding, as illustrated by adenosine diphosphoribose which fails to exhibit negative cooperativity. Occupancy of the adenine subsite by adenine is important for stabilization of the enzyme against thermal denaturation. Whether the stabilization is due to an altered conformation of the subunits or stabilization of the preexisting structure of the apoenzyme cannot be determined from these studies. However, nicotinamide hypoxanthine dinucleotide does not contribute to enzyme stability although it serves as a substrate and shows negative cooperativity.
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PMID:Cooperativity and noncooperativity in the binding of NAD analogues to rabbit muscle glyceraldehyde-3-phosphate dehydrogenase. 17 63


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