NAD^(+)-linked glutamate dehydrogenase(L-glutamate : NAD^(+) oxidoreductase, desminating, EC 1.4.1.3) of rabbit erythrocytes during cytosol differentiation has been studied. The rabbits were injected with phenylhtdrazine on day 0.1 and 3 at intervals, the blood samples were taken by cardiac puncture, and the activity of glutamate dehydrogenase in cytosolic and mitochondrial fraction of reticulocytes was assayed by the method of King. The results observed were as follows:
1. Activity of cytosolic glutamate dehydrogenase was about 4.0 unit from normal rabbit erythrocyte, however no appreciable enzyme activity was found in mitochomdrial fraction.
2. In phenylhydrazine-produced reticulocytosis, the total glutamate dehydrogenase activity was maximal on 5 day, about 34.5mits which is abouty 8.3 times higher than that of normal value.
3. The increase in total activity of glutamate dehydrogenase during the induction of reticulocytosis was primarily to 6.7 folds increase in the cytoselic isozyme(K_(s)=0.01161 ; K_(d)=0.0043 ; t1/2=161.16 hrs.), for mitochondrial isozyme(K_(s)=0.0675, K_(d)=0.090 ; t1/2=77.0 hrs).
4. The rate of constants follwing recovery from phenylhydrazine treatment were, Ks=0.0161, K_(d)=0.0320; 1/2=21.66 hrs, for cytosolic isozyme and K_(s)=0.0916 ; K_(d)=0.0229 ; t1/2=30.26 hrs, for mitochondrial isozyme.
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