Study on Association between Lignin and Pectin Using Carbon-13 Isotopic Tracer
It is well known that lignin deposits after polysaccharide in the plant cell wall.The first lignified region is the primary wall which contains a large amount of pectin.Pectin is mainly composed of uronic acid,the carboxyl group of which tends to react with quinone methides of lignin to form lignin-pectin complexes.It is of importance to investigate the chemical bonds between lignin and pectin in the deposition process of lignin in cell walls.To understand the detailed configuration of lignin-pectin complexes and to simulate the lignin deposition process in the initial stage.Pectin-DHP(dehydrogenation polymer; DHP)complexes were prepared in vitro from coniferin-α-13C in the presence of pectin,horseradish peroxidase,β-glucosidase and glucose oxidase.The dioxan/water insoluble fraction of pectin-DHP complexes(Pectin-DHP-Insoluble;PDHPI)which was labelled by 13C at α-position of lignin moieties was obtained after extraction by dioxan/water(96/4,v/v).The obtained α-13C labelled PDHPI was analysed by FT-IR and hydrolyzed by pectinase to remove the pectin not linked to lignin moieties.The hydrolyzates were fractionated by centrifugation and gel-adsorption into water-soluble fraction(PDHPI-WS)and water-insoluble fraction(PDHPI-IS).The 13C-NMR spectra of the α-13C labelled PDHPI-WS and PDHPI-IS proved that lignin could chemically bond with pectin through esters,benzyl ether linkages and ketal linkages,which occurred at α-position of phenylpropane units.It was also identified that β-O-4,β-β,β-5,β-1 were main substructures in the DHP.Moreover,there was significant amount of coniferyl alcohol and coniferyl aldehyde structures.Small amount of substructures such as vanillin,α-methylene phenylpropane units were also found.The method of carbon-13 isotopic tracer provides detailed and reliable information about the chemical bonds between lignin and pectin.
lignin pectin, LCC carbon-13 isotopic tracer
Yimin Xie Peng Wang Jianyun Fan
Key Lab.of Paper Science and Technology of Ministry of Education,Shandong Institute of Light Industr Putian Institute of Supervision & Testing on Product Quality,Putian 351100,P.R.China
国际会议
第二届国际造纸与环境学术会议(The Second International Papermaking & Environment Conference)
天津
英文
224-227
2008-05-14（万方平台首次上网日期，不代表论文的发表时间）