OXIDATION OF FATTY ALCOHOL IN THE COTYLEDONS OF JOJOBA SEEDLINGS

During the germination of jojoba (Simmondsia chinensis) seeds, fatty alcohols are formed from the hydrolysis of stored wax esters. The cotyledon extract has the ability to convert fatty alcohols to fatty aldehydes in the presence of molecular oxygen and subsequently to fatty acids when NAD+ is added. The two enzymes which catalyze these activities have been partially characterized. The fatty alcohol oxidase utilizes molecular oxygen as the electron acceptor and dodecyl alcohol as the preferred substrate and has an optimal pH for activity at 9.0. The fatty aldehyde dehydrogenase also has an optimal pH for activity at 9.0, an apparent Km value of 4 × 10-6 m for decyl aldehyde, an apparent Km value of 2.5 × 10-4 m for NAD+, and a substrate preference for dodecyl aldehyde. NAD+ is a much better electron acceptor than NADP+, FAD, or flavin mononucleotide for the aldehyde dehydrogenase. Both enzyme activities are inhibited by p-chloromercuribenzoate and its effect is completely reversed by dithiothreitol. The whole fatty alcohol oxidation system is capable of oxidizing monounsaturated fatty alcohols which are the physiological substrates in jojoba cotyledons. The two enzyme activities are absent in the dry seed and increase drastically during germination. Both enzymes are localized primarily on the membrane of the wax bodies, although they may be present in other cellular membranes. © 1979.