Biosynthesis and cell-wall deposition of a pectin-xyloglucan complex in pea
Biosynthesis and cell-wall deposition of a pectin-xyloglucan complex in pea
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DOI：
10.1007/s00425-005-1560-2
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发表时间：
2005-10-01
期刊：
影响因子：
4.3
通讯作者：
Brett, CT
中科院分区：
文献类型：
--
作者：
Cumming, CM;Rizkallah, HD;Brett, CT
由黄化豌豆上胚轴制备的富含高尔基体的酶制剂，将来自 UDP-[U-C-14] 半乳糖的 [U-C-14] 半乳糖掺入果胶-木葡聚糖复合物的 1,4-β-半乳聚糖侧链中。该复合物可以与纸结合，并被果胶降解酶和木葡聚糖特异性内切葡聚糖酶降解。使用凝胶渗透色谱法评估复合物及其酶降解的含半乳聚糖片段的分子大小。黄化豌豆茎用[U-C-14]蔗糖标记1 h，用EDTA或NaOH提取新合成的细胞壁多糖，并通过离子交换色谱法分级分离。以这种方式获得的 NaOH 提取的酸性放射性多糖也被果胶降解酶和木葡聚糖特异性内切葡聚糖酶降解。放射性糖成分的分析表明存在果胶和木葡聚糖的中性糖特征。对 NaOH 提取的酸性细胞壁多糖的总非放射性中性糖组成的分析表明，果胶-木葡聚糖复合物是该组织中细胞壁的一般特征。
Golgi-enriched enzyme preparations prepared from etiolated pea epicotyls incorporated [U-C-14] galactose from UDP-[U-C-14] galactose into the 1,4-beta-galactan sidechains of a pectin-xyloglucan complex. This complex could bind to paper and was degraded both by pectin-degrading enzymes and by a xyloglucanspecific endoglucanase. Gel permeation chromatography was used to assess the molecular size of the complex and of enzymically-degraded, galactan-containing fragments of it. Etiolated pea stems were labelled with [U-C-14] sucrose for 1 h, and the newly-synthesised cell wall polysaccharides were extracted with EDTA or NaOH and fractionated by ion-exchange chromatography. The NaOH-extracted, acidic radioactive polysaccharides obtained in this way were also degraded both by pectin-degrading enzymes and by xyloglucan-specific endoglucanase. Analysis of the radioactive sugar composition indicated that neutral sugars characteristic of both pectin and xyloglucan were present. Analysis of the total non-radioactive, neutral sugar composition of the NaOH-extracted, acidic cell-wall polysaccharides indicated that pectin-xyloglucan complexes were a general feature of the cell wall in this tissue.