The enzymic and non-enzymic degradation of colneleic acid, an unsaturated fatty acid ether intermediate in the lipoxygenase pathway of linoleic acid oxidation in potato (Solanum tuberosum) tubers

Abstract

Colneleic acid is an unsaturated ether fatty acid derived from linoleic acid via a lipoxygenase-mediated enzyme pathway. It is degraded (a) by an enzyme in potato tubers which is heat-labile and non-dialysable and (b) by a model system containing catalytic amounts of Fe2+ ions. Both enzyme- and Fe2+-catalysed systems have similar properties with respect to pH optima (pH5.0–5.5), oxygen requirement (0.6–0.7 mol of O2 consumed/mol of ether degraded), inhibitors and reaction products. An unstable product breaks down to C8 and C9 carbonyl fragments. Both systems are inhibited by low concentrations of antioxidants (e.g. 5μm-butylated hydroxytoluene) and some chelating agents (e.g. 5μm-diethyldithio-carbamate). The model system is strongly inhibited by metal ions, particularly Cu2+ and Fe3+, at 20μm. Hydrogen peroxide and haemoproteins do not substitute for the enzyme or Fe2+ ions but the non-haem iron protein, ferredoxin, does catalyse the degradation.