Polygalacturonase-mediated dissolution and depolymerization of pectins in solutions mimicking the pH and mineral composition of tomato fruit apoplast
Polygalacturonase-mediated dissolution and depolymerization of pectins in solutions mimicking the pH and mineral composition of tomato fruit apoplast
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DOI：
10.1016/j.plantsci.2007.03.008
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发表时间：
2007-06-01
期刊：
影响因子：
5.2
通讯作者：
Huber, Donald J.
中科院分区：
文献类型：
--
作者：
Almeida, Domingos P. F.;Huber, Donald J.
研究了多聚半乳糖醛酸酶（PG）对在常规缓冲液（30 mM乙酸钠，150 mM NaCl，pH 4.5）中孵育的成熟绿色番茄果实的细胞壁以及在模拟成熟绿色果实（MG）和成熟果实（R）的质外体溶液的缓冲液中孵育的成熟绿色番茄果实的细胞壁中果胶溶解和解聚的影响。果胶从细胞壁中的溶解在C-缓冲液中比在NIG-或R-缓冲液中高得多。在C-缓冲液中培养的缓冲的苯酚灭活的细胞壁释放4.9 μ g mg-1果胶，当加入PG时增加到86.4 μ g mg-1。在R-缓冲液中，PG使果胶从非活性细胞壁中的溶解从0.5 μ g mg（-1）增加到18.3 μ g mg（-1）。然而，当在模拟成熟绿色水果的缓冲液中进行测定时，添加的PG没有增加果胶溶解。在C-缓冲液和R-缓冲液中，由于果胶甲酯酶的活性，活性细胞壁释放的糖醛酸始终低于非活性细胞壁。从细胞壁中提取的CDTA可溶性果胶的凝胶过滤曲线显示，该酶能够水解不溶性的、离子结合的果胶。这些数据支持的想法，pH值和矿物质成分的果实质外体提供了一种手段，细胞壁代谢的生化调节。(C)2007爱思唯尔爱尔兰有限公司保留所有权利。
The effects of polygalacturonase, (PG) on pectin dissolution and depolymerization were examined in cell walls from mature-green tomato fruit incubated in a conventional (C) buffer (30 mM sodium acetate, 150 mM NaCl, pH 4.5) and in buffers mimicking the apoplastic solution of mature-green (MG) and ripe fruit (R). Pectin dissolution from cell walls was much higher in C-buffer than in NIG- or R-buffers. Buffered phenol inactivated cell walls incubated in C-buffer released 4.9 mu g mg- I pectin, which increased to 86.4 pg mg(-1) when PG was added. In the R-buffer, PG increased the pectin dissolution from inactive cell walls from 0.5 to 18.3 mu g mg(-1). However, when the assay was conducted in buffer mimicking mature-green fruits, added PG did not increase pectin dissolution. The release of uronic acids from active cell walls in C-buffer and R-buffer was consistently lower than that from inactive walls due to the activity of pectinmethylesterase. Gel filtration profiles of CDTA-soluble pectins extracted from cell walls previously incubated in C-buffer or R-buffer with PG reveal that the enzyme is capable of hydrolyzing insoluble, ionically bound, pectins. These data support the idea that pH and mineral composition of the fruit apoplast provide a means for biochemical regulation of cell wall metabolism. (C) 2007 Elsevier Ireland Ltd. All rights reserved.