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Submitted to: Meeting Abstract
Publication Type: Abstract Only Publication Acceptance Date: 5/31/2000 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: Several legume species have been shown to metabolize 3(Z)- alkenals to 4-hydroxy-2(E)-alkenals. The pathway involves dioxygenase oxidation of 3(Z)-alkenals into 4-hydroperoxy-2(E)- alkenals followed by peroxygenase action that reduces one molecule of hydroperoxide to hydroxide followed by creation of a second molecule of 4-hydroxy-2(E)-alkenal via intermediate epoxidation and rearrangement of 3(Z)-alkenal. In this oxygenation, 3(Z)-alkenal substrates are hydroperoxide lyase products, 3(Z)-hexenal and 3(Z)-nonenal. Since 9-hydroxy- traumatin has been observed to originate from the 13- hydroperoxide of linoleic acid, it is implicated that 9(Z)- traumatin is also a substrate. It has been shown that lipoxygenase can serve as the dioxygenase involved in the primary oxygenation of 3(Z)-alkenals. This oxidation has some unique features, among which the most intriguing is a stimulation by the presence of fatty acid hydroperoxide. Although lipoxygenase participates in the formation of 4-hydroperoxy-2(E)-alkenals, it was demonstrated that 4-hydroxy-2(E)-nonenal is a potent suicide inhibitor of lipoxygenase. Interestingly, the presence of linoleic acid protects lipoxygenase from inactivation, possibly by competitive occupation of the active site. It is known that 4- hydroxy-2(E)-nonenal readily forms Michael adducts with histidine. Since 4-hydroxy-2(E)-nonenal obviously is capable of occupying the lipoxygenase active site, it is likely that it reacts with one or more of the three histidines coordinating with iron. |
