针叶木硫酸盐浆中残留木素的GIF体系仿酶降解机理的研究

由于针叶木硫酸盐浆中的残留木素含有大量难降解的LCC结构及其它缩合型木素结构,所以硫酸盐浆的分离木素可以用作难降解型木素大分子的一种结构模型。文章采用Cu2+/吡啶/过氧化氢组成的GIF仿酶体系对马尾松硫酸盐未漂浆的纤维素酶酶解木素(CEL)进行了仿酶降解,并对降解产物进行了分离和化学组成分析。通过FT-IR以及GC-MS测定,解析了CEL在降解过程中的结构变化,并对CEL的仿酶降解机理进行了探讨。研究结果表明:这种仿酶降解方法对浆中残留木素有较强的降解能力,一部分木素大分子被氧化降解为香草醛和香草酸等低分子化合物,使得降解后的产物中羰基和羟基增多。研究发现木素在仿酶体系中存在苯环及其侧链上C-H键的破坏、木素结构中Ca-Cb连接键的断裂、苯环的开环等反应。因此,该项研究可以为开发纸浆的仿酶漂白技术提供理论依据。

Biomimetic Degradation of Residual Lignin in Softwood Kraft Pulp by GIF System

Cellulolytic enzyme lignins(CELs) of the unbleached kraft pulp from Pinus massoniana Lamb were isolated and treated by copper(Ⅱ)/pyridine/peroxide complex (GIF system) in order to understand the degradation pathway in biomimetic bleaching. Infrared spectra and GC-MS determination were used to analyze the change of chemical structure of CEL during the reaction. The results show that the copper(Ⅱ)/pyridine/peroxide system was effective for the degradation of CEL. It was found that some hydroxyl and carboxyl groups were introduced and some low molecule compounds such as vanillin and vanillic acid were produced after the treatment. These results illustrate that oxidation of lignin in side chain can cleave the linkage between the units of lignin. It is also proved that oxidative cleavage of C-H bond of the aromatic ring and side chain, Ca-Cb cleavage of lignin substructure units and the opening of aromatic ring were caused by the GIF system.