垂序商陆叶细胞壁结合锰机制研究

Mechanism of Manganese Binding to Leaf Cell Wall of Phytolacca americana L.

垂序商陆是一种典型的锰超积累植物,细胞壁在其累积解毒锰的过程中起了一定的作用.通过细胞壁吸附实验,研究不同p H和不同锰浓度对细胞壁吸附锰的影响,并采用傅立叶红外光谱及同步辐射X-射线吸收光谱技术探讨了其吸附机制.结果表明,垂序商陆叶细胞壁吸附锰的最适p H值为5~6;其吸附行为可用Langmuir模型较好地描述(R2=0.978 5),并计算得其最大吸附量为62.50μmol·g-1.细胞壁上的羟基(—OH)和羰基(—CO)是结合锰的主要位点;锰周围第一配层为氧原子,其配位数为6.3,Mn—O键长为0.216 nm,细胞壁与锰主要以内配层模式相结合.

Phytolacca americana L.( P. americana) is a manganese( Mn) hyperaccumulator and cell wall plays an important role in the accumulation and detoxicity of Mn. We studied the impact of p H and Mn initial concentration on the binding of Mn by the leaf cell wall of P. americana,and explored the binding mechanisms by Fourier Transform Infrared Spectroscopy( FTIR) and synchrotron-based X-ray Absorption Fine Structure( XAFS) Spectroscopy. The results show that the optimum p H of Mn bingding for the leaf cell wall is between 5 and 6. The adsorption behavior of leaf cell wall can be described by Langmuir equation( R2= 0. 978 5) and the maximum adsorption of Mn on the leaf cell wall is 62. 50 μmol·g- 1. Hydronyl and carbonyl groups are involved in the binding of Mn on the leaf cell wall. The Mn absorbed on the leaf cell wall is bonded by 6. 3 oxygen around,and the bond length of Mn—O is 0. 216 nm,which indicates the binding mechasnism of Mn to cell wall was inner-sphere complexation.