The incorporation of citrate carbon into fatty acids.

Long-chain fatty acids are synthesized from citrate in an undialyzed soluble enzyme system from pigeon liver at a rate comparable to that observed when acetate is used as a precursor. The first enzymic step for citrate incorporation is probably its breakdown to acetyl-CoA and oxaloacetate catalyzed by the citrate~cleavage enzyme. Experiments with variously labeled citrate show good incorporation of the acetyl portion of citrate into fatty acids, and a poor incorporation of the oxaloacetyl portion into fatty acids. The incorporation of the oxaloacetyl portion of citrate as well as the acetyl portion has b ~ n shown to be avidin sensitive. The enzymic sequence from the oxaloacetyl portion remains uncertain.