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. Supported in part by NSF Grant No. PCM76 01495.