Inhibition of gluconeogenic enzymes by free fatty acids and palmitoyl coenzyme A.

The effects of free fatty acids on rat liver phosphoenolpyruvate carboxykiuase (EC 4.1.1.32), pyruvate carboxylase (EC 6.4.1. I), and glucose 6-phosphatase (EC 3.1.3.9) were determined to evaluate the suggestion that free fatty acid inhibition of key glycolytic enzymes constitutes a specific inhibitory effect. Activities of ah of these gluconeogenie enzymes were found to be markedly inhibited by long chain free fatty acids as well as by palmitoyl coenzyme A. The manner of the inhibition of gluconeogenic enzymes was indistinguishable from that reported for the glycolytic enzymes. It is therefore concluded that such effects in vitro of free fatty acids or long chain acyl-CoA esters on glycolytic and gluconeogenic enzymes may not be relevent for the regulation of metabolism in Go.