Isolation And Structure Elucidation Of Sugar Chains From Enteromorpha Prolifera

Polysaccharide from Enteromorpha has a variety of biological activities.However, few studies of sugar chain structure were reported. In this paper, Degradsefor polysaccharides from E.prolifera were produced by microbial fermentation andpolysaccharide was treated by enzymatic degradation. Combining with analyticalinstruments, structure of sugar chain was analyzed. The main results were as follows:Polysaccharide was prepared by hot water extraction, the content ofpolysaccharide was16.4%. Ethanol precipitation condition was determined by singlefactor experiments. Concentration of polysaccharide was chosen at15.0mg/mL,5volumes of ethanol were added and the precipitation time was2h, to finish thepreliminary purify of polysaccharide. After anion exchange chromatography, E-1andE-2were obtained. E-1and E-2were purified by gel filtration chromatography onceagain, then desalted and freeze dried. E-1was white solid and E-2was pale yellowsolid.Feature and composition of E-1and E-2were analyzed. The average molecularweight of E-1was103.4kDa. Monosaccharide composition analysis by gaschromatography showed that E-1contained large amounts of glucose, small amountsof xylose and rhamnose, monosaccharides (rhamnose: xylose: glucose) was in a molarratio of1:4.8:57.9. IR spectrum indicated that E-1didn’t exist sulfate groups oruronic acids. The average molecular weight of E-2was620.3kDa. Monosaccharidecomposition analysis by liquid chromatography showed that E-2contained a largenumber of rhamnose, glucuronic acid and xylose, galactose and glucose were in asmall amount and the molar ratio of each monosaccharide (rhamnose: glucuronic acid:glucose: galactose: xylose)was15.2:5.3:1:1.5:4.7. IR spectrum showed thepresence of sulfate groups and uronic acids. Content of Sulfate and uronic acid weremeasured as (7.7±1.1)%and (14.4±0.3)%.Structure of E-1and E-2were also analyzed. Polysaccharide degrading enzymes produced by microbial fermentation were added, the enzymatic reaction wasperformed for5h at35℃in order to prepare oligosaccharide, P4gel was used topurify them. Three kinds of oligosaccharide fragment called E-1a, E-1b and E-1cwere produced by E-1, while five kinds of oligosaccharide fragments called E-2a,E-2b, E-2c, E-2d and E-2e were produced by E-2. MS chromatography of eacholigosaccharide from E-1showed that the molecular weight of E-1a was666Da,considered as glucose tetrasaccharide, molecular weight of E-1b was504Da,considered as glucose trisaccharide, molecular weight of E-1c was342Da, consideredas glucose disaccharide. For MS and MS-MS chromatography of E-2, MSspectrometry results showed that molecular weight of E-2b, E-2c, E-2d and E-2eoligosaccharides were760Da,628Da,402Da and244Da. E-2b analyzed by MS-MSspectrometry with orient sample and the reduction sample, the monosaccharidesequences of these oligosaccharides were, GlcUA-Rha(OSO3H)-Rha(OSO3H)-(Xyl),(non-reducing end from left).Degradation by enzymatic hydrolysis, a series of oligosaccharides rich in GlcUAand Rha(OSO3H) were obtained. They improved the library of marine oligosaccharide,also contributed to analyze the structure of sugar chain and the research ofrelationship between structure and biological function of polysaccharide.