ALL 3 ACYL MOIETIES OF TRILINOLEIN ARE EFFICIENTLY OXYGENATED BY RECOMBINANT HIS-TAGGED LIPID BODY LIPOXYGENASE IS VITRO

Recently, me found a 13-lipoxygenase in germinating cucumber cotyledon s, which was located at the lipid body membrane. Based on its products formed mobilization of storage lipids seems to be initiated by this 1 3-lipoxygenase, For biochemical characterization its cDNA was expresse d as Histagged protein, Active recombinant enzyme was obtained from lo w temperature cultivation of E, coli after affinity purification, It ( i) exhibited an unchanged region specificity, and (ii) showed a pH opt imum of 7.2 against trilinolein as substrate, We compared its ability to oxygenate trilinolein with the one of another 13-lipoxygenase, soyb ean lipoxygenase-1. At the pH optimum of soybean lipoxygenase-1 (9.0), trilinolein was oxygenated only to 28% of the amount converted by the lipid body lipoxygenase. Moreover, trilinolein oxygenation by soybean lipoxygenase-1 leads mainly to monohydroperoxy derivatives, whereas o xygenation by lipid body LOX leads to a trihydroperoxy derivative. (C) 1998 Federation of European Biochemical Societies.