[Purification and some physico-chemical properties of glutamate dehydrogenase from beef brain]

A procedure for purification of glutamate dehydrogenase (GDH; L-glutamate NAD(P) oxidoreductase, EC 1.4.1.3) from beef brain has been developed. The enzyme preparation obtained has the specific activity of 6.7 units per mg of protein (192-fold enhance with a 30% yield of total activity of the homogenate). In some of its physico-chemical properties (pH optimum of catalyzed reactions, molecular weight, subunit structure, thermal stability) the brain GDH is identical to the enzyme from beef liver. The Km values for most of the coenzymes and substrates for the enzyme studied do not exceed those for beef liver enzyme more than 1,5--2-fold. The only exception is the Km value for glutamate, which in the case of brain GDH is 4 times less than that for the liver enzyme. The results obtained suggest that upon interaction with NAD the brain GDH reveals a relatively higher affinity for L-glutamate and L-ketoglutarate as compared to the liver enzyme.