Pyruvate dehydrogenase activity in hamster small intestine during development

Abstract

Total pyruvate dehydrogenase [E.C. 1.2.4.1] activities in hamster intestine increased from 40 nmol/min (munits) per g of intestine in the fetal animals to 460 munits/g in the adult, whereas the fraction of the enzyme in the active form increases from 34-42% of the total activity over the same period. However, a complete conversion of the enzyme into the active form was observed in the neonatal animal immediately after birth. Results from experiments in vitro suggested that pyruvate dehydrogenase activation is controlled, in part, by the [NAD+]/[NADH] ratio. This proposal was tested in vivo by examining the proportion of the enzyme in the active form during conditions when the [NAD+]/[NADH] ratio was markedly altered, and the data show a direct relationship between the mitochondrial redox state and activity of the active form.