DO SPECIFIC LINOLEATE 13-LIPOXYGENASES INITIATE BETA-OXIDATION

The germination process of oilseed plants is characterized by a mobili zation of the storage lipids which constitute the major carbon source for the growing seedling. Despite the physiological importance of the lipid mobilization, the mechanism of this process is not well understo od. Recently, it was found that a specific linoleate 13-lipoxygenase i s induced during the stage of lipid mobilization in various oilseed pl ants and that this enzyme is translocated to the membranes of the lipi d storage organelles, the so called lipid bodies. Lipoxygenase express ion was paralleled by the occurrence of enantiospecific hydro(pero)xy polyenoic fatty acid derivatives in the storage lipids suggesting the in vivo action of the enzyme. Furthermore, it was reported that oxygen ated polyenoic fatty acids, in particular as 13(S)-hydro(pero)xy-9(Z), 11(E)-octadecanoic acid [13(S)-H(P)ODE], are cleaved preferentially f rom the storage lipids when compared with their non-oxygenated linolea te residues. These findings may suggest that 13(S)-H(P)ODE may constit ute the endogenous substrate for beta-oxidation during lipid mobilizat ion of oilseed plants. (C) 1997 Federation of European Biochemical Soc ieties.