Oxidation of unsaturated fatty acids

Plant leaf systems have been incubated under various conditions with uniformly labeled oleic acid, and the breakdown products identified by gas-liquid chromatography. Young green leaves of the castor plant (Ricinis gibsonii) and of the field pea plant (Pisum sutiuum) catabolize oleic acid by an oxygen-requiring pathway to heptadec-8-enaI which is then dehydrogenated by an NAD-coupled mechanism to heptadec8-enoic acid. Further a-oxidation occurs with the production of hexadec-7-enoic acid and lower homologues. The a-oxidizing ability is associated with the fraction of homogenized leaves that sediments between 700 and 7000 X g; the partly purified acetone powders of leaves retain this enzymatic activity in soluble form. Preliminary studies with uniformly labeled linoleic acid suggest that a-oxidation of polyunsaturated acids also occurs in the leaf systems.