Transaminase reaction rates, transport activities and TCA cycle analysis by post‐steady state ¹³C NMR

In this work, we present the post‐steady state analysis of the TCA cycle and a closed form solution to the rate of label washout from the C4 carbon of glutamic acid through the transaminases and the malate‐aspartate shuttle and then through α‐ketoglutarate dehydrogenase. We demonstrate using a model of this problem that the rate of label washout depends not only on the flux through α‐ketoglutarate dehydrogenase, but most importantly on the activity of the malate‐aspartate shuttle as determined by the forward and reverse fluxes through the transaminases and by the rate of transport of glutamate and a‐ketoglutarate across the mitochondrial membrane.