Activation of phosphofructokinase and pyruvate kinase by 6 phosphogluconate in chicken liver ( Callus domesticus): No evidence for a regulatory role

1. 1. Phosphofructokinase and pyruvate kinase in crude extracts of chick liver were activated by 6 phosphogluconate at subsaturating concentrations of their respective substrates. 2. 2. The apparent Ka for phosphofructokinase was 0.79 mM and for pyruvate kinase 0.44 mM. 3. 3. Total pentose phosphate dehydrogenase activity was low in the livers of both fed and starved chicks. 4. 4. Hepatic 6 phosphogluconate concentration was too low to be measured accurately by a conventional spectrophotometric method. 5. 5. It is concluded that the concentration of 6 phosphogluconate is too low for it to have a role in the regulation of phosphofructokinase and pyruvate kinase activities in chicken liver.