Studies on enzyme system involved in formation of 'Green-Odor'

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Hydroperoxide cleaving enzyme, hydroperoxide lyase(HPO lyase), was first purified to homogeneous state from membrane fraction of tea leaves. The activity was separated by hydroxylapatite gel chromatography into two fractions, HPO lyases I and II, and their molecular weights were 55, 000 and 53, 000, respectively, . as estimated by SDSpolyacrylamide gel electrophoresis. Several lines of evidence are presented to show that HPO lyase I is a native form. Almost the same pH-activity profiles were observed with these two forms of HPO lyase. Antioxidants which are potent inhibitors for lipoxygenase such as nordihydroguaiaretic acid and butylated hydroxyanisole inhibited the activity of HPO lyase I. Activity for 13-hydroperoxide of alpha-linolenic acid was about 10 times higher than that for 13-hydroperoxide of linoleic acid, but pobitional isomer, 13-hydroperoxide of gamma-linolenic acid was a poor substrate.C_6-Aldehydes emitted from intact tea leaves were quantitatively analyzed. Emission of the aldehydes temporarily increased on middle May when enzyme activities involved in aldehyde formation from lipid began to increase. The amounts of C_6-aldehydes accumulated in tea leaves also increased temporarily. But, compositions of accumulated C6-aldehydes did not always coincide with those of emitted ones.