Enzyme system catalyzing formation of cis-3-hexenal and n-hexanal from linolenic and linoleic acids in Japanese silver (Farfugium iaponicum Kitamura) leaves

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Leaf alcohol (cis-3-hexenol) and leaf aldehyde (trans-2-hexenal) are responsible for the green odor in leaves and fruits. cis-3-Hexenal, a precursor of cis-3-hexenol and trans-2-hexenal, was produced from linolenic acid by a homogenate of Farfugium japonicum (Japanese silver) leaves. n-Hexanal was produced from linoleic acid by a homogenate of the leaves. The enzyme system catalyzing formation of C_6-aldehydes from linolenic and linoleic acids was localized in chloroplast lamellae, and required oxygen for reaction. C_<18>-unsaturated fatty acids such as linolenic acid, linolenic acid and γ-linolenic acid, which have carboxyl groups and cis-1, cis-4-pentadiene systems including a double bond at C-12, acted as substrates, and C_6-aldehydes (cis-3-hexenal or n-hexanal), but not C_9-aldehydes, were produced from them. The properties of the enzyme system in chloroplasts were as follows: optimal pH 7.0; stable at pH 5 to 7; thermolabile and no activity at 50℃. These properties were, very similar to those of tea chloroplasts. The enzyme system could be solubilized from chloroplasts by 2% Triton X-100, but was very unstable in solubilized form.
日本植物生理学会の論文