[Catalytic properties of 6-phosphogluconate dehydrogenase from rat liver in normal state and during toxic hepatitis].

Experimental toxic hepatitis is accompanied by a decrease of 6-phosphogluconate dehydrogenase (6PGD, 1.1.1.44) activity in rat liver. Enzyme preparations of 6PGD, obtained from livers of control group rats and animals with toxic exhibit the same molecular mass of 114.2 +/- 5.8 kDa. However G6PD isolated from liver of animals with toxic hepatitis exhibited altered Km and pH-optimum values. Reduced glutathione inhibited 6PGD-activity from the liver of control group rats and did not affect the enzyme from liver of animals with toxic hepatitis. Inhibition effect of oxidized glutathione is stronger in the pathological state. Malate, citrate, 2-oxoglutarate and isocitrate activated the enzyme from control animals, but did not the enzyme isolated from animals with hepatitis. Regulation of 6PGD-activity from liver of control and experimental animals by some nucleotides (NAD, ADP, AMP) and ribose-5-phosphate was also different.