Detection of Divinyl Ether Synthase Activity and a Novel Oxylipin (1'Z)–Colneleic Acid in Asparagus (Asparagus officinalis L.)

Resumo

The activity of divinyl ether synthase (EC: 4.2.1.121), an enzyme involved in the lipoxygenase cascade of unsaturated fatty acids in plants, has been found in the roots and stalks of asparagus Asparagus officinalis L. Incubation of homogenates of roots and/or etiolated stalks of Asparagus officinalis L. with linoleic acid results in the formation of mainly divinyl ether (9Z,11Z,1'E)-12-(1'-hexenyloxy)-9,11-dodecadienoic acid ((11Z)-etheroleic acid), as well as a minor amount of its geometric isomer (9Z,11E,1'E)-12-(1'-hexenyloxy)-9,11-dodecadienoic acid (etheroleic acid). These compounds are derived from linoleic acid by the sequential action of regiospecific 13-lipoxygenase and divinyl ether synthase. Moreover, a minor compound, whose amount increases after the incubation of homogenates with the 9-hydroperoxide of linoleic acid ((9S,10E,12Z)-9-hydroperoxy(10,12)–octadecadienoic acid), has been found. This compound has been identified as (8E,1'Z,3'Z)-9-(1',3'-nonadienyloxy)-8-nonenoic acid ((1'Z)-colneleic acid). These data suggest that nonphotosynthetic tissues of asparagus exhibit the activity of a novel 13/9-specific divinyl ether synthase.