Regulation of Fatty Acid Biosynthesis by Physical Exercise Mechanisms of Inhibition

In partially purified cell-free extracts of rat liver, nonexhaustive, daily exercise results in a 40 to 90% inhibition of FAB by decreasing the catalytic activity of acetyl coenzyme A carboxylase (ACC), the rate-limiting enzyme in the de novo FAB pathway in vitro. ACC inhibitory mechanisms are postulated to include: phosphorylation of ACC and production of a noncompetitive inhibitory substance. Data obtained after purification of rat liver ACC to homogeneity suggest that decreased ACC activity in exercised rats cannot be attributed to the well-documented control of ACC by reversible phosphorylation, but are more likely due to the presence of a noncompetitive inhibitory substance located in the partially purified cell-free extract of rat liver