Fatty acid biosynthesis in the developing endosperm ofCocos nucifera

Endosperm tissue of developing coconut endosperm incorporated [14C] acetate and [14C]‐malonate into [14C]C8‐C18 fatty acids. The distribution of [14C] label into the various fatty acids mimicked the distribution of endogenous fatty acids at early and middle stages of endosperm development. Although [14C] C8‐C18 fatty acids were taken up rapidly by endosperm tissue slices, no elongation occurred; [14C] stearic acid was not desaturated to oleic. Cell free preparations have also been obtained from this tissue that readily incorporated [14C] malonyl‐CoA into a range of [14C] fatty acids in the presence of ACP and NADH at pH 7.0. Employing this system, a number of experiments were designed to determine the mechanism of chain length termination. In contrast to intact tissue slice experiments, cell‐free extracts yielded as principal products palmitic and stearic acid, although up to 20% were shorter chain acids. A number of possible mechanisms for chain length termination were proposed and tested.