Enzymatic Formation of Capsaicinoid from Vanillylamine and Iso-type Fatty Acids by Cell-free Extracts ofCapsicum annuumvar.annuumcv. Karayatsubusa

Cell-free extracts of placenta of Capsicum annuum var. annuum cv. Karayatsubusa catalyzed the formation of capsaicinoid from vanillylamine and 7-methylocatnoyl CoA (iso-C9:0-CoA), 8-methylnonanoyl CoA (iso-C10:0-CoA), 8-methyl-6-nonenoyl CoA (iso-C-10:1CoA), or 9-methyldecanoyl CoA (iso-C11:0-CoA). Iso-type fatty acid-activating reaction required CoA, ATP and Mg++ as cofactors. Among acyl-CoAs examined, iso-C9:0-CoA was used most effectively as acyl donor for capsaicinoid formation. 5-methylhexanoyl CoA (iso-C7:0-CoA), 6-methylheptanoyl CoA (iso-C8:0-CoA), 10-methylundecanoyl CoA (iso-C12:0-CoA) and decanoyl CoA (n-C10:0-CoA) were not used as acyl donor. When equivalent amounts of iso-C9:0-CoA, iso-C10:0-CoA, iso-C10:1-CoA, and iso-C11:0-CoA were added together as acyl donors, nordihydrocapsaicin was the major product, occupying more than 60% of the total capsaicinoid formed. The optimum pH for capsaicinoid formation was around 9.0, when iso-C10:0-CoA was used as acyl donor.