Linoleic , α-linolenic acid biosynthesis in plant leaves and a green alga

1. [1-14C]Oleic acid is shown to be directly converted to [1-14C]linoleic acid , to [1-14C]α-linolenic acid in both plant leaves , the green alga Chlorella vulgaris. 2. This conversion is inhibited by anaerobiosis , by the absence of light. 3. The preparation of subcellular fractions from C. vulgaris which desaturate both oleic acid , linoleic acid is described. 4. Demonstrable cofactors are molecular oxygen , NADH or NADPH. The CoA ester of oleic acid is the preferred substrate. 5. Fractionation studies suggest that the desaturase activity resides in the chloroplast , an oleic acid activation enzyme occurs in the cytoplasm.