Fatty acid synthesis by isolated chromoplasts from the daffodil. Energy sources and distribution patterns of the acids.

1. Fatty acid synthesis in isolated intact chromoplasts from [1-(14)C]acetate was made possible by using ATP, ADP (via adenylate kinase), and, with decreasing efficiency, UTP, CTP, and GTP as energy sources. 2. The glycolytic path from dihydroxyacetone phosphate to acetyl-CoA operates within the chromoplasts. The glycolytic intermediates, especially 2-phosphoglycerate and phosphoenolpyruvate, served as very effective energy donors for fatty acid synthesis by phosphorylating the endogenous adenine nucleotide pool. 3. In the presence of exogenous ATP or ADP, appreciable amounts of in vitro formed fatty acids were found as acyl-CoA and subsequent products, mainly phosphatidylcholine. When other energy sources were used most of the acids formed were in the free form, and to a minor extent, in the phosphatidic acid and diacylglycerol fractions. Similar results have recently been reported for spinach chloroplasts (Kleinig and Liedvogel 1979, FEBS Lett.101, 339-342).