LIGHT-DEPENDENT STEP OF DE NOVO SYNTHESIS OF LONG-CHAIN FATTY-ACIDS IN SPINACH-CHLOROPLASTS

The light-dependent step in de novo synthesis of long chain fatty acids by spinach chloroplasts was determined by examining the levels of the intermediates. Isolated spinach chloroplasts could incorporate [1-14C]acetate into acetyl-CoA and fatty acids in the light, whereas in the dark the radioactivity was effectively incorporated only into acetyl-CoA, but not into malonyl-CoA and fatty acids. Furthermore, disrupted chloroplasts, which can metabolized exogenous CoA derivatives, could incorporate approx. 35% as much [2-14C]-malonyl-CoA into fatty acids in the dark as in the light. These results indicate that light is essential only for acetyl-CoA carboxylase activity in fatty acid synthesis in spinach chloroplasts. © 1979 Elsevier/North-Holland Scientific Publishers Ltd.