Reaction of N-bromosuccinimide with reduced ring systems. Apparent protection of glutamate dehydrogenase by reduced nicotinamide-adenine dinucleotide

Biochemistry ◽  
1972 ◽  
Vol 11 (16) ◽  
pp. 3088-3090 ◽  
Author(s):  
Murray R. Summers
Keyword(s):  
Glutamate Dehydrogenase ◽  
Nicotinamide Adenine Dinucleotide ◽  
Nicotinamide Adenine ◽  
Ring Systems ◽  
Reduced Ring ◽  
Reduced Nicotinamide Adenine Dinucleotide

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.

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.

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