纤维素前驱物6-13 C标记示踪研究纤维素与木质素连接方式

摘要

从细胞壁多糖的角度分析糖单元与木质素苯丙烷结构单元之间的共价键连接方式,合成了带6-13C标记的纤维素前驱物尿苷二磷酸葡萄糖,并将其与苯丙氨酸解氨酶( PAL)的抑制剂L-2-氨氧基-3-苯基丙酸( AOPP)及外源性木质素前驱物松柏醇-β-D-葡萄糖苷一起投入生长中的银杏植物体内,分析结果证明了(6-13C)尿苷二磷酸葡萄糖是对植物中纤维素进行选择性13C标记的合适的前驱物。从正常生长的银杏新生木质部组织提取木质素-碳水化合物复合体( LCC),并用纤维素酶和半纤维素酶酶解LCC得LCC酶解产物( EDLCC)。红外光谱及13C NMR检测LCC和EDLCC,分析证实了纤维素6位碳与木质素以苯甲醚键方式连接。%In this paper, carbohydrate part of the lignin-carbohydrate complexes( LCC) in cell wall was labelled with 13C and traced with 13C NMR . Cellulose precursor, i. e. , uridine diphoshphate glucose-[6-13C], was synthesized, and injected into a living ginkgo tree together with lignin inhibitor AOPP and exogenous lignin precursor. It is proved that uridine diphoshphate glucose-[6-13C] is a suitable precursor for selective 13C-enrichment of cellulose in a plant. The specifically 13C-enriched LCC was isolated from the newly formed xylem of ginkgo shoots. Then it was degraded by cellulase and hemicellulase. Thus the lignin-rich fractions,which were called enzyme-degraded LCC ( EDLCC) , were obtained. By determining their FT-IR and 13C NMR spectra, information confirms that the bonds between C6 position of glucose units in cellulose andα-carbons of lignin side chain are benzyl ether linkage.