13C-2H双同位素示踪法研究硫酸盐浆中残余木质素的仿酶降解

Study on Biomimetic Degradation of Residual Lignin in Kraft Pulp by 13C-2H Dual Isotope Tracer

中文关键词:  硫酸盐法蒸煮  残余木质素  双同位素示踪  仿酶降解  银杏

Key Words:kraft pulping  residual lignin  dual isotope tracer  biomimetic degradation  ginkgo

中文摘要:

      本研究合成了松伯醇葡萄糖苷-［α-¹³C］，将其与碳水化合物前驱物D-葡萄糖-［6-²H₂］及苯丙氨酸解氨酶（Phenylalanine Ammonialyas，PAL）的抑制剂羧甲氧基胺半盐酸盐（AOA）投入到处于生长状态的银杏枝条中，得到¹³C和²H双同位素标记的银杏木粉。对银杏木粉进行硫酸盐法蒸煮，所得浆料通过酶水解法分离及纯化后得到¹³C和²H双同位素标记的纤维素酶解木质素（CEL），用GIF-sur-Yvette型（GIF型）以及水杨醛（salicylaldehyde）、乙二胺（ethylenediamine）与铜离子形成的络合物（Cu（Salen））仿酶处理CEL，以进一步除去其中的木质素和木质素-碳水化合物复合体（LCC）。利用核磁共振技术（¹³C NMR和¹H NMR）对仿酶处理后的残余物进行分析，结果表明经GIF型仿酶处理后的残余物中木质素结构单元间主要以β-5、β-O-4、β-1结构连接，少量木质素与纤维素之间以缩醛键和苯甲醚键（约6.7%）连接。Cu（Salen）型仿酶处理后的残余木质素结构单元间主要以β-O-4、β-1结构连接，仿酶处理后的CEL存在少量纤维素，但是没有发现木质素与纤维素之间的苯甲醚键和缩醛键的连接键信号。¹H NMR差示谱图只显示出部分未取代的纤维素多糖信号，未发现木质素与多糖的连接键信号，这表明Cu（Salen）型仿酶对LCC具有较强的降解能力。

Abstract:

      In this study， coniferin-［α-¹³C］ was synthesized， and then injected into a growing shoot of Ginkgo biloba L. together with the D-glucose-［6-²H₂］ of polysaccharide precursor and inhibitor （carboxymethoxyamine hemihydrochloride， AOA） of phenylalanine ammonialyas， to obtain ¹³C and ²H double isotope-labeled ginkgo wood mill. The wood mill was cooked with kraft method and the obtained pulp was treated by enzymatic hydrolysis to obtain ¹³C and ²H double isotope labeled cellulolytic enzyme lignin（CEL）. The purified CEL was subjected to biomimetic treatment with GIF-sur-Yvette （GIF） and Cu（Salen） system which was composed of salicylaldehyde， ethylenediamine and Cu²⁺ to further remove lignin and lignin-carbohydrate complexes （LCC）. The residues after biomimetic treatment were analyzed by nuclear magnetic resonance （¹³C NMR and ¹H NMR）. The results showed that the lignin structural units in the residues after GIF system biomimetic treatment were mainly connected with β-5， β-O-4 and β-1 substructures， while a small amount of lignin was connected with cellulose by acetal bond and benzyl ether linkage （about 6.7%）. The residual lignin structural units after biomimetic treatment by Cu（Salen） system were mainly connected with β-O-4 and β-1 structures. It was found that there was a small amount of cellulose after the biomimetic treatment in CEL， but no signal of the benzyl ether bond and acetal bond between lignin and cellulose was found. The ¹H NMR differential spectrum only showed the signals of some unsubstituted polysaccharides， but the connection between lignin and polysaccharides was not found. The results showed that Cu（Salen） system biomimetic catalytic oxidation had relatively strong degradation ability for LCC.