MEDIUM-CHAIN ACYL-ACP HYDROLYSIS ACTIVITIES OF DEVELOPING OILSEEDS

Cell-free preparations from the seed tissues of three different species that accumulate medium chain triglycerides were examined for medium chain acyl-ACP hydrolysis. Activities with qualitatively appropriate medium chain length specificities were found, suggesting that a thioesterase has evolved in diverse plant families for the production of C-8, C-10 and C-12 fatty acids. A pathway kinetic argument is presented to explain quantitative differences between the thioesterase specificities determined in vitro and the fatty acids accumulated in vivo.