Kinetic properties of glutamate dehydrogenase from the gills of Arapaima gigas and Osteoglossum bicirrhosum

1978 ◽  
Vol 56 (4) ◽  
pp. 809-813 ◽  
Author(s):  
J. H. A. Fields ◽  
W. R. Driedzic ◽  
C. J. French ◽  
P. W. Hochachka
Keyword(s):  
Glutamate Dehydrogenase ◽  
Nicotinamide Adenine Dinucleotide ◽  
Energy Charge ◽  
Adenosine Monophosphate ◽  
Adenosine Diphosphate ◽  
Nicotinamide Adenine ◽  
Kinetic Properties ◽  
Guanosine Diphosphate ◽  
Arapaima Gigas ◽  
Reduced Nicotinamide Adenine Dinucleotide

Glutamate dehydrogenase was isolated from the gills of Arapaima gigas and Osteoglossum bicirrhosum and kinetically characterized, in order to determine whether there was any alteration in the ability of the gills to generate ammonia associated with the development of an air-breathing life-style. The catalytic and regulatory properties of both enzymes were found to be very similar. They were activated by leucine, adenosine monophosphate, and adenosine diphosphate, and inhibited by guanosine triphosphate, guanosine diphosphate, and adenosine triphosphate. Inhibition by nicotinamide adenine dinucleotide and reduced nicotinamide adenine dinucleotide was strong in both cases. It was concluded that both enzymes were regulated by a combination of the energy charge of the cell and the redox potential. There is no evidence for any qualitative alteration of the gills to produce ammonia from amino acids in the air breather, Arapaima gigas, as compared with the water breather, Osteoglossum bicirrhosum.

FACTORS INFLUENCING TETRAZOLE REDUCTION BY REDUCED NICOTINAMIDE–ADENINE DINUCLEOTIDE IN PIGEON-HEART MITOCHONDRIA

1967 ◽  
Vol 45 (2) ◽  
pp. 299-307 ◽  
Author(s):  
C. L. Talesara ◽  
M. C. Blanchaer
Keyword(s):  
Adenosine Triphosphate ◽  
Respiratory Chain ◽  
Nicotinamide Adenine Dinucleotide ◽  
Inorganic Phosphate ◽  
Adenosine Monophosphate ◽  
Adenosine Diphosphate ◽  
Heart Mitochondria ◽  
Nicotinamide Adenine ◽  
Tetrazolium Chloride ◽  
Reduced Nicotinamide Adenine Dinucleotide

The effect of adenosine triphosphate, adenosine diphosphate, adenosine monophosphate and inorganic phosphate on the reduction of 2-(p-iodophenyi)-3-p-nitrophenyl-5-phenyl tetrazolium chloride (INT) to its formazan by reduced nicotinamide-adenine dinucleotide (NADH) was studied in pigeon-heart mitochondria. Formazan production was followed at 540 mμ in 2.2 ml medium containing 0.4–0.5 mg mitochondrial protein, 0.22 M mannitol, 0.067 M sucrose, 0.02 M Tris–chloride, 0.02 mM EDTA, 0.5–3.0 mM INT, and 38 μM NADH at pH 7.2 and 28 °C. By means of the respiratory inhibitors Amytal, rotenone, antimycin A, and cyanide, it was shown that INT diverts electrons from the respiratory chain principally at the flavoprotein level. In contrast to its inhibitory effect on "the O2-linked oxidation of NADH, 10 mM adenosine triphosphate stimulated the reaction rate and formazan yield in the present system. Equimolar inorganic phosphate also increased the initial velocity but adenosine diphosphate and adenosine monophosphate did not. Preliminary kinetic studies suggest that NADH, but not INT, combines with the form of NADH dehydrogenase in the respiratory chain with which adenosine triphosphate reacts.

Purification and some properties of the citrate synthase from a marine Pseudomonas

1978 ◽  
Vol 24 (3) ◽  
pp. 215-221 ◽  
Author(s):  
Azucena I. Higa ◽  
Esther Massarini ◽  
Juan José Cazzulo
Keyword(s):  
Molecular Weight ◽  
Nicotinamide Adenine Dinucleotide ◽  
Gel Electrophoresis ◽  
Citrate Synthase ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Adenosine Monophosphate ◽  
Adenosine Diphosphate ◽  
Reduced Nicotinamide Adenine Dinucleotide ◽  
Different Molecular Weight

Citrate synthase (citrate-oxaloacetate lyase (CoA acetylating), EC 4.1.3.7) has been purified to electrophoretic homogeneity from a marine Pseudomonas. The enzyme was made up of identical subunits, with a molecular weight of about 53 000, as determined by sodium dodecyl sulphate – polyacrylamide gel electrophoresis. The native enzyme (citrate synthase II, CS II) could be dissociated by dialysis against 20 mM phosphate (Pi), pH 7; the enzyme thus obtained (citrate synthase I, CS I) was still active, but presented different molecular weight and kinetic and regulatory properties.CS II was activated by adenosine monophosphate (AMP), Pi, and KCl, and inhibited by reduced nicotinamide adenine dinucleotide (NADH), being apparently insensitive to adenosine triphosphate (ATP) and adenosine diphosphate (ADP). The inhibition by NADH was completely counteracted by 0.1 mM AMP, but not by 50 mM Pi or 0.1 M KCl. The activation by KCl and Pi, or by KCl and AMP was nearly additive, whereas that by AMP and Pi, was not. The activators acted essentially by increasing Vmax, although they also caused a decrease in the Km values.CS I was inhibited by ATP, ADP, AMP, and KCl, and was insensitive to NADH.CS I could be reassociated after elimination of Pi by dialysis, regaining the higher molecular weight and the activation by AMP characteristic of CS II.

scholarly journals Theoretical Analysis of the Built-in Metabolic Pathway Effect on the Metabolism of Erythrocyte-Bioreactors That Neutralize Ammonium

Metabolites ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 36
Author(s):  
Evgeniy Protasov ◽  
Larisa Koleva ◽  
Elizaveta Bovt ◽  
Fazoil I. Ataullakhanov ◽  
Elena Sinauridze
Keyword(s):  
Steady State ◽  
Glutamate Dehydrogenase ◽  
Pentose Phosphate Pathway ◽  
Nicotinamide Adenine Dinucleotide ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Pentose Phosphate ◽  
Nicotinamide Adenine ◽  
Limiting Factor ◽  
Glutamate Dehydrogenase Activity ◽  
Reduced Nicotinamide Adenine Dinucleotide

The limitations of the efficiency of ammonium-neutralizing erythrocyte-bioreactors based on glutamate dehydrogenase and alanine aminotransferase reactions were analyzed using a mathematical model. At low pyruvate concentrations in the external medium (below about 0.3 mM), the main limiting factor is the rate of pyruvate influx into the erythrocyte from the outside, and at higher concentrations, it is the disappearance of a steady state in glycolysis if the rate of ammonium processing is higher than the critical value (about 12 mM/h). This rate corresponds to different values of glutamate dehydrogenase activity at different concentrations of pyruvate in plasma. Oxidation of reduced nicotinamide adenine dinucleotide phosphate (NADPH) by glutamate dehydrogenase decreases the fraction of NADPH in the constant pool of nicotinamide adenine dinucleotide phosphates (NADP + NADPH). This, in turn, activates the pentose phosphate pathway, where NADP reduces to NADPH. Due to the increase in flux through the pentose phosphate pathway, stabilization of the ATP concentration becomes impossible; its value increases until almost the entire pool of adenylates transforms into the ATP form. As the pool of adenylates is constant, the ADP concentration decreases dramatically. This slows the pyruvate kinase reaction, leading to the disappearance of the steady state in glycolysis.

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