[Purification of glutamate dehydrogenase from the rabbit liver and study of its major physico-chemical properties]. / Ochistka glutamatdegidrogenazy pecheni krolika i izuchenie osnovnykh fiziko-khimicheskikh svoistv.

Highly purified preparations of glutamate dehydrogenase were obtained from mitochondrial and cytoplasmic fractions of rabbit liver by affinity chromatography on CL-Sepharose 4B modified by adenosine diphosphate. Some physico-chemical properties of the purified enzymes (e. g., specific activity, molecular weight, quaternary structure, stability against denaturating effect of urea, pH optimum of catalyzed reactions, Km values for substrates and coenzymes) were found to be identical. The sole difference was detected in the ability of enzyme preparations to be activated by adenosine diphosphate. The activation of the cytoplasmic enzyme is 160%, that of mitochondrial glutamate dehydrogenase is 230-240% under the same conditions.

[Heterogeneity and regulation of glutamate dehydrogenase activity in mammalian brain and liver]. / Geterogennost' i reguliatsiia aktivnosti glutamatdegidrogenazy v mozgu i pecheni mlekopitaiushchikh.

The present report concerns the study of the catalytic properties and the coenzyme affinity of glutamate dehydrogenase (GDH) and its isoenzymes in various preparations of the brain and liver as well as the different regulatory mechanisms controlling the ratio of the rates of biogenesis and breakdown of glutamate (Glu). The investigations carried out showed that GDH activity of various preparations of brain and liver (crystalline enzymes, cellular extracts and mitochondria) are markedly different from each other by their catalytic and regulatory properties as well as by their coenzyme activity. The data obtained make us conclude that nicotinamide-hypoxanthine-nucleotide (deaminoNAD) is a more effective coenzyme in the oxidative deamination of Glu, than other piridine nucleotides (NAD, NADP, deamino-NADP). It is supposed that in the formation of ammonia and amino acids in brain and especially liver, together with other known mechanisms an important role may be ascribed to the process of transdeamination. In this aspect, as a co-factor of oxidative deamination of Glu deamino-NAD (D-NAD) is thought to be of significant importance.