PHOSPHOFRUCTOKINASE AND FUMARATE HYDRATASE IN DEVELOPING RAT BRAIN

The developmental patterns of phosphofructokinase, fumarate hydratase and lactate dehydrogenase were determined and compared using homogenates of rat brain. Phosphofructokinase activity, expressed in terms of tissue wet wt., was relatively constant from 5 days before birth to 8 days postnatal; a 110 per cent increase in activity occurred between 12 and 21 days of age, when adult levels were achieved. The degree of inhibition of phosphofructokinase by 1-0 mM-ATP changed little during development; inhibition by 2-5 mM-citrate was about 50 per cent in both newborn and adult brain. Phosphofructokinase development more closely resembled that of lactate dehydrogenase than that of fumarate hydratase.