Variations in tissue contents of coenzyme A thio esters and possible metabolic implications

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Abstract
Procedures are described for the estimation of total CoA, long-chain fatty acyl-CoA and acetyl-CoA in tissues. A method for determining the amount of CoA derivatives of fatty acids saturated in the 2, 3-position is also given, and was applied to tissue extracts. The proportions of the total CoA of liver combined with long-chain fatty acids and with acetate are increased in rats which were starved, starved and then fed with fat, or in which diabetes was induced by alloxan. Refeeding starved rats with sugar causes a decrease in the liver fatty acyl-CoA; the effect on acetyl-CoA is less marked. The inhibition by palmitoyl-CoA of ''fatty acid synthase'' and citrate ATP lyase (citrate cleavage enzyme) was studied. Citrate synthase (EC 4. 1. 3. 7, condensing enzyme) is very strongly inhibited by palmitoyl-CoA. This inhibition may be prevented or reversed by serum albumin. The effects on cellular metabolism of variations in the acylation state of CoA are discussed. The rate of fatty acid synthesis may be directly regulated by the concentration of tissue long-chain acyl-CoA. The effect of alteration in acetyl-CoA concentration on ketogenesis is mentioned, and the relationship in liver between acetyl-CoA and citrate is discussed.