ON THE STRUCTURES OF MWL AND LCC IN RICE STALK BY CARBON-13 ISOTOPIC TRACER TECHNOLOGY
In order to obtain detailed information about milled wood lignin (MWL) and lignin-carbohydrate complexes (LCC) of rice plant, a specifically 13C-enriched lignin precursor ( i. e., coniferin-side chain-α-13C ) was synthesized and fed into the internode cavities of the stalk of growing rice plant (Oryza sativa L.). 13C-enriched MWL and LCC were separated from the matured rice stalk according to the Bjorkmans method. The spectra of 13C-NMR and FT-IR of 13C-enriched MWL indicated that lignin could connect with carbohydrates through the benzyl ether bond. It was also shown that β-O-4, β-β, β-5 and β-1 were the main substructures of lignin in MWL of rice plant. There were some minor substructures as α-O-4 units. LCC was analyzed after hydrolysis with a mixture of cellulase and hemicellulase. The enzymatic hydrolyzates were fractionated into water-soluble and water-insoluble fractions after centrifugation. The water-soluble fractions were further fractionated by adsorption chromatography. The fragments abundant in LC bonds were collected for 13C-NMR and FT-IR determination. The spectra of 13C-NMR and FT-IR of the water-insoluble fractions and LCC-rich water-soluble fractions from enzymatic digests of 13C-enriched LCC indicated that lignin was linked to carbohydrate by benzyl ether bond and ketal linkage at the Cα-position of side chain of phenylpropane units. It was also proved that β-O-4, β-β, β-5 and β-1 were the main substructures of lignin in LCC labelled with 13C of rice plant. The carbon-13 isotopic tracer method provides detailed and reliable information about the chemical bonds between lignin and carbohydrates.
LCC MWL rice stalk isotopic tracer
Yang Haitao Shang Wei Yao Lan Xie Yimin Zhan Huaiyu
School of Chemical and Environmental Engineering,Hubei University of Technology, Wuhan, 430068,China Key Laboratory of Paper Science and Technology of Ministry of Education, Shandong Institute of Light State Key Lab. of Microbial Technology, Shandong University, Ji’nan, 250100, China State Key Lab. of Pulp & Paper Engineering, South China University of Technology, Guangzhou,510640,
国际会议
广州
英文
394-397
2010-11-08（万方平台首次上网日期，不代表论文的发表时间）