33 青葉アルコールの生合成(その3) : 植物緑葉中に於けるリノレン酸のO_2添加・開裂反応の周辺

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Leaf alcohol (cis-3-hexenol) and leaf aldehyde (trans-2-hexenal), which are formed from cis-3-hexenal, are widely distributed in fresh leaves, vegetables and fruits and are responsible for "green odour" characteristic of leaves. We have demonstrated that the "green odour" (C_6-alcohols and -aldehydes) are biosynthesized by the enzymatic oxygenation (E'_2) and subsequent cleavage reaction (E"_2) from linolenic acid, which are liberated from phospholipid and neutral fats by acylhydlase in chloroplasts. In this paper, we describe the stereochemistry, the substrate specificity, the reaction mechanism and plant physiological regulation factor in enzymatic oxygenative-cleavage reaction. 1) The enantiomeric composition of the hydroperoxide produced by E'_2 was determined by GLC and the regiospecific and geometrical compositions were determined by HPLC. In the enzymatic cleavage reaction of 13-hydroperoxide to C_6-aldehyde, this compound was produced from L-form of hydroperoxide enantioselectively. 2) The isotope effect was observed in the E"_2 reaction by enzymes such as tea leaves, tea chloroplast and watermelon seedling. 3) The oxygenative activities have related to temperature and solar radiation and cleavage reaction activities have the correlation with the chlorophyll content of green leaves.
天然有機化合物討論会の論文
1983-09-15