Department of Biological Sciences, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, Japan.
J Plant Physiol. 2011 Nov 1;168(16):1997-2000. doi: 10.1016/j.jplph.2011.05.010.
Oxalate oxidase (OXO) utilizes oxalate to generate hydrogen peroxide, and thereby acts as a source of hydrogen peroxide. The present study was carried out to investigate whether apoplastic OXO modifies the metabolism of cell wall-bound ferulates in wheat seedlings. Histochemical staining of OXO showed that cell walls were strongly stained, indicating the presence of OXO activity in shoot walls. When native cell walls prepared from shoots were incubated with oxalate or hydrogen peroxide, the levels of ester-linked diferulic acid (DFA) isomers were significantly increased. On the other hand, the level of ester-linked ferulic acid (FA) was substantially decreased. The decrease in FA level was accounted neither by the increases in DFA levels nor by the release of FA from cell walls during the incubation. After the extraction of ester-linked ferulates, considerable ultraviolet absorption remained in the hemicellulosic and cellulose fractions, which was increased by the treatment with oxalate or hydrogen peroxide. Therefore, a part of FA esters may form tight linkages within cell wall architecture. These results suggest that cell wall OXO is capable of modifying the metabolism of ester-linked ferulates in cell walls of wheat shoots by promoting the peroxidase action via supply of hydrogen peroxide.
草酸氧化酶（OXO）利用草酸生成过氧化氢，因此充当了过氧化氢的来源。本研究旨在探讨质外体 OXO 是否会改变小麦幼苗细胞壁结合阿魏酸的代谢。OXO 的组织化学染色显示细胞壁被强烈染色，表明在芽壁中存在 OXO 活性。当用草酸或过氧化氢孵育来自芽的天然细胞壁时，酯键型二阿魏酸（DFA）异构体的水平显著增加。另一方面，酯键型阿魏酸（FA）的水平则大幅降低。FA 水平的降低既不是由 DFA 水平的增加，也不是由孵育过程中细胞壁中 FA 的释放所导致的。在提取酯键型阿魏酸后，半纤维素和纤维素部分仍残留相当大的紫外吸收，用草酸或过氧化氢处理后会增加这种吸收。因此，一部分 FA 酯可能在细胞壁结构内形成紧密的键合。这些结果表明，细胞壁 OXO 通过提供过氧化氢来促进过氧化物酶的作用，从而能够改变小麦芽细胞壁中酯键型阿魏酸的代谢。
