Citrate Cleavage Enzyme and Fatty Acid Synthesis*

A series of experiments was performed to test the proposal of others that citrate cleavage enzyme (EC 4.1.3.8) regulates the rate of fatty acid synthesis in rat liver. The results show that, in recovery from fasting, fatty acid synthesis increased markedly without change in citrate cleavage enzyme activity. After the administration of alloxan, fatty acid synthesis decreased prior to any change in citrate cleavage enzyme. Substitution of a high carbohydrate, low fat diet resulted in large increases in citrate cleavage enzyme activity without concomitant change in lipogenesis. The addition of purified citrate cleavage enzyme from rat liver to the fatty acid-synthesizing system from fasted animals did not restore fatty acid synthesis. It was concluded that citrate cleavage enzyme does not play a primary regulatory role in fatty acid synthesis.