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

1978; NRC Research Press; Volume: 56; Issue: 4 Linguagem: Inglês

10.1139/z78-112

1480-3283

Jeremy H. A. Fields, William R. Driedzic, Christopher J. French, Peter W. Hochachka,

Mass Spectrometry Techniques and Applications

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.