Metabolism of acetate by cellfree preparations from spinach leaves.

Smirnov (1) has reported the biosynthesis of long chain fatty acids by chloroplasts. However, the reaction mixtures used in the experiments were not as complete as was found necessary for maximal fatty acid synthesis in animal (24) and other plant tissues (5). Smirnov (1) observed that fatty acid synthesis was stimulated by light and suggested that its action was of fundamental importance in the formation of acetyl coensyme A. It seemed desirable to determine whether fatty acid synthesis in chloroplasts is similar to that reported for other enzyme preparations. The synthesis is particularly interesting because of the large increase in polyunsaturated fatty acids which occurs when leaves are illuminated (6). This paper describes the conditions necessary for the incorporation of acetate into long chain fatty acids by spinach chloroplasts and demonstrates the relationships with other pathways of acetate metabolism.