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

首次从茶叶膜组分中分离纯化了过氧化氢裂解酶，即过氧化氢裂解酶（HPO裂解酶）。活性通过羟基磷灰石凝胶色谱分离成两个组分，HPO裂解酶I和II，其分子量分别为55，000和53，000。用SDS聚丙烯酰胺凝胶电泳测定。几条线的证据表明，HPO裂解酶I是一个天然的形式。对于这两种形式的HPO裂合酶，观察到几乎相同的pH-活性曲线。抗氧化剂是脂氧合酶的有效抑制剂，如去甲二氢愈创木酸和丁基羟基茴香醚抑制HPO裂解酶I的活性。α-亚麻酸的13-氢过氧化物比亚油酸的13-氢过氧化物的活性高10倍左右，但γ-亚麻酸的13-氢过氧化物是一个很差的底物。醛类的排放暂时增加5月中旬时，酶活性参与醛形成脂质开始增加。茶叶中C_6-醛类物质的积累量也暂时增加。但是，积累的C6-醛的组成并不总是与排放的那些一致。

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.