Citrate and the conversion of carbohydrate into fat. A comparison of citrate and acetate incorporation into fatty acids

Abstract

Rates of incorporation into fatty acids of citrate and acetate were compared. The ratio of the rates of citrate and acetate incorporation by liver preparations varies widely, depending on the nutritional state of the animal. It is depressed tenfold during starvation, and can increase by as much as 100-fold on re-feeding. The same ratio is approximately three in the high-speed supernatant fluid prepared from lactating mammary gland. The rates of citrate incorporation, but not those of acetate incorporation, are more than sufficient to account for the rates of fatty acid synthesis that occur in intact liver. Together they are almost sufficient to account for the rates of fatty acid synthesis that occur in intact mammary gland. The role of the microsomes on citrate incorporation is complex, three distinct types of behaviour being recognizable. At very low concentrations microsomes have no effect or inhibit, at intermediate concentrations they stimulate, and at high concentrations they inhibit precursor incorporation.