The biosynthesis of long-chain fatty acids by lettuce chloroplast preparations

Abstract 1. 1. It is demonstrated that the major site of biosynthesis of saturated fatty acids from C 10 to C 18 and of oleic acid in leaves is the chloroplast. 2. 2. The co-factors required in the presence of light are ATP, CoA, Mg 2+ , CO 2 and inorganic phosphate. 3. 3. In the dark greatly diminished synthesis occurs despite the presence of a full complement of cofactors. 4. 4. As in photosynthetic phosphorylation the synthesis of fatty acids is inhibited by NH 3 and 3( p -chlorophenyl) 1,1-dimethyl urea but not by dinitrophenol. 5. 5. Under anaerobic conditions the biosynthesis of oleic acid drops markedly but that of the saturated acids is relatively unaffected. 6. 6. Isolated chloroplasts are less effective in utilising the C 8 , C 10 , C 12 and C 14 saturated fatty acids for the biosynthesis of oleic acid than is the intact leaf. Both malonic and acetic acids are, however, readily utilised.