47 みどりの香りの発現(その1) : 緑葉中のα-リノレン酸への酵素的O_2添加・開裂反応(口頭発表の部)

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We have demostrated that "Green Odour" of green leaves consists of six volatile compounds of C_6-aldehydes and C_6-alcohols including leaf aldehyde, (2E)-hexenal, and leaf alcohol, (3Z)-hexenol. These volatile compounds are biogenerated from linolenic acid and linoleic acid via their respective hydroperoxides in leaves. The biogeneration involves four enzymes. Among these enzymes, lipoxygenase and hydroperoxide lyase are especially interesting. The two enzymes are found to bind to the lamella membrane of chloroplasts in green leaves. The lipoxygenase catalyzes a stereoselective oxygenation of unsaturated fatty acids having a (1Z,4Z)-pentadiene system to produce 13-(S)-hydroperoxides, whereas, the hydroperoxide lyase cleaves the bond between C-12 and C-13 of these hydroperoxides into C_6-aldehydes. We will present the enzymic cleavage mechanism of 13-(S)-hydroperoxides to C_6-aldehydes and C_<12>-oxo-acids and substrate specificities for the enzymic oxygenation of the unsaturated fatty acids to 13-(S)-hydroperoxides in tea chloroplasts, using an entire series of synthetic (ω6Z,ω9Z)-C_<13>-C_<20>-dienoic acids and dienols.
天然有機化合物討論会の論文
1988-09-26