Metabolism of Acetate by Sheep Liver Homogenates

Abstract

The metabolism of acetate was studied in sheep liver homogenates. Contrary to previous reports, acetate was oxidized by fresh liver homogenates, and acetyl-CoA was oxidized by both fresh and frozen-stored liver homogenates in the presence of the cofactors nicotinamide adenine dinucleotide (NAD) and carnitine. With these 2 factors, oxidation plateaus after 20-30 minutes, unless a 4-carbon TCA cycle acid, such as succinate, is present as a primer, in which case the straight line rate of oxygen uptake continues for 60-80 minutes. Direct measurement of acetyl-CoA formation showed this to be the limiting step in utilization of acetate by sheep liver, and the step lost in frozen-stored liver homogenates.