Matsui K, Irie M, Kajiwara T, Kakuno T, Hatanaka A
Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University, Japan.
Phytochemistry. 1993 Apr;32(6):1387-91. doi: 10.1016/0031-9422(93)85143-f.
The lipoxygenase activity from cucumber cotyledons grown with their embryonic axis was separated into two fractions having M(r)s of 90,000 and 96,000, respectively, by hydrophobic chromatography. However, from de-embryonated cucumber cotyledons, only one form of lipoxygenase having a M(r) of 90,000 was purified. The three lipoxygenases could not be distinguished from each other either immunologically or by their enzymatic properties. Furthermore, peptide maps of the 90,000 and 96,000-lipoxygenases were identical. In a crude homogenate of cucumber cotyledons, the 96,000-lipoxygenase was rapidly degraded to the 90,000-form. Thus, it was inferred that the 90,000-lipoxygenase was probably the 96,000-form which had lost a peptide fragment of 6,000. It is suggested that there is a specific proteolytic activity for the degradation of 96,000-lipoxygenase. Estimation of changes in the proteolytic activity during seedling growth suggests that the activity at least partly contributes to the rapid in vivo degradation of cucumber cotyledon lipoxygenase.
通过疏水层析法，将带有胚轴生长的黄瓜子叶中的脂氧合酶活性分离成两个部分，其相对分子质量分别为90,000和96,000。然而，从去胚的黄瓜子叶中，仅纯化出一种相对分子质量为90,000的脂氧合酶形式。这三种脂氧合酶在免疫学上或酶学性质上均无法相互区分。此外，相对分子质量为90,000和96,000的脂氧合酶的肽图是相同的。在黄瓜子叶的粗匀浆中，相对分子质量为96,000的脂氧合酶迅速降解为相对分子质量为90,000的形式。因此，推测相对分子质量为90,000的脂氧合酶可能是失去了一个6,000肽片段的相对分子质量为96,000的形式。表明存在一种特异性的蛋白水解活性用于降解相对分子质量为96,000的脂氧合酶。对幼苗生长过程中蛋白水解活性变化的估计表明，该活性至少部分促成了黄瓜子叶脂氧合酶在体内的快速降解。
