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Dynamism of apoplast

质外体的动力学

基本信息

批准号：
07304054
负责人：
SAKURAI Naoki
金额：
$ 9.73万
依托单位：
Hiroshima University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

The following results were obtained ;(1) Five glucanases bound to barley cell walls were identified as, [1] endo-1,3 ; 1,4-glucanase, [2] endo-1,3-glucanase-1, [3] endo-1,3-glucanase-2, [4] exoglucanase-1, and [5] exoglucanase-2. The enzymes involved in 1,3 ; 1,4-glucan degradation in the cereal plants are [1] and [4].(2) The enzymic activity that converts indoleacetaldehyde to indole-3-acetic acid was found in barley cell walls. The Km was 5muM which is lower than that for the cytoplasmic enzyme with similar activity (31muM). Apoplast of dark grown squash hypocotyls containes the concentration of indole-3-acetic acid 5 times higher than the symplast.(3) Essential element, boron, which was known to be localized at cell walls, was bound to rhamnogalacturoans by a diol-ester linkage and cross-linked two polysaccharides.(4) It was suggested that when xyloglucan was breakdown during elongation growth, xyloglucans becomes susceptible to enzyme action after cellulose molecules into which zyloglucan was inserted, was degraded by endoglucanase activity.(5) In is unlikely that plant has RGD peptide homologs similar to those found on animal cells.The technique with pH dependent fluorescence dye revealed that the phosphate lever of vacuoles were homeostatically regulted by the cooperative action of mechanism wiht which the cytoplasmic phosphate level was regulated.These results clearly demonstrate that the apoplast is the site where substances prerequisite for the plant life, such as plant hormones, polysaccharide-related enzymes, or inorganic ions, are dynamically metabolized.

结果表明：（1）5种与大麦细胞壁结合的葡聚糖酶被鉴定为：[1]内切-1，3; 1，4-葡聚糖酶，[2]内切-1，3-葡聚糖酶-1，[3]内切-1，3-葡聚糖酶-2，[4]外切葡聚糖酶-1和[5]外切葡聚糖酶-2。禾谷类植物中参与1，3; 1，4-葡聚糖降解的酶为[1]和[4]。(2)在大麦细胞壁中发现了将吲哚乙醛转化为吲哚-3-乙酸的酶活性。Km值为5 μ M，低于活性相近的胞质酶Km值（31 μ M）。暗培养西葫芦下胚轴质外体中吲哚-3-乙酸的浓度比共质体高5倍。(3)必需元素硼，已知定位于细胞壁，通过二醇-酯键和交联的两种多糖与鼠李糖半乳果糖结合。(4)有人建议，当木葡聚糖在伸长生长过程中被分解时，木葡聚糖在插入了木葡聚糖的纤维素分子被内切葡聚糖酶活性降解后变得对酶作用敏感。(5)植物中不可能存在与动物细胞中类似的RGD肽同源物。pH依赖性荧光染料技术表明，液泡中的磷酸盐水平是由细胞质磷酸盐水平调节机制的协同作用来调节的。这些结果清楚地表明，质外体是植物生命所必需的物质，如植物激素，多糖相关酶或无机离子被动态代谢。