The development of glycolytic and pentose phosphate shunt enzymes in human brain.

A quantitative enzyme analysis of 32 fetal human brains of 6--42 weeks gestational age range was carried out for the major glycolytic and pentose phosphate shunt enzymes. A critical period of raised enzyme levels was observed at 14 weeks. The glycolytic rate was probably controlled by the activities of hexokinase and phosphofructokinase which appear from the development patterns to have independent genetic sites. A rise in most enzyme activities was experienced in the final weeks of gestation towards levels consistent with those of adult tissues. Pentose phosphate shunt enzyme levels remained virtually unchanged during gestation after 14 weeks.