黑木耳多糖AAPS-3的化学结构

利用逆流色谱分离技术从黑木耳中分离了黑木耳多糖AAPS-3。通过完全水解、甲基化、一维和二维1H和13C核磁共振(NMR)阐明AAPS-3的化学结构。经完全水解证实AAPS-3主要由Glc单糖组成,用HPLC方法测得其分子量为4.83×105,通过甲基化反应数据和1H和13C NMR等分析发现AAPS-3为由β-D-1,4-Glc,β-D-1,3-Glc和β-D-1,6-Glc残基构成主链的葡聚糖。     

Study of the extracellular polysaccharides produced by a blue-green alga,Anabaena flos-aquae A-37

Summary Two types of polysaccharides were separated from the extracellular polysaccharide produced by Anabaena flos-aquae A-37 by ion exchange chromatography. The neutral polysaccharide is composed of mainly glucose with minor amounts of xylose in a molar ratio of 8:1. Glucose is believed to constitute the polysaccharide core to which xylose is attached. The acidic polysaccharide is composed of glucose and uronic acid as the major monomers with equal amounts of xylose and ribose as the minor constituents. The molar ratio of the monomers found in the acidic polymer is 6:1:1:10 as glucose: xylose: ribose: uronic acid. Chemical analyses showed that the extracellular polysaccharide consists of more neutral polymer (62%) than the acidic polymer (38%).     

Water-soluble polysaccharides from Ginkgo biloba leaves.

The water-soluble polysaccharides from dried Ginkgo biloba leaves were isolated after exhaustive extraction with organic solvents. The polysaccharide mixture could be separated into a neutral (GF1) and two acidic (GF2 and GF3) polysaccharide fractions by ion exchange chromatography. According to the Mr distribution GF1 and GF3 seemed to be homogenous, whereas GF2 could be further fractionated into two subfractions (GF2a and GF2b) by gel permeation chromatography. GF1 (Mr 23,000) showed the structural features of a branched arabinan. The main chain was composed of 1,5-linked arabinose residues and three in 12 arabinose molecules were branched via C-2 or C-3. GF2a (Mr 500,000) consisted mainly of 1,2,4-branched mannose (29%), 1,4-linked glucuronic (32%) and galacturonic (8%) acid as well as terminal rhamnose (25%). After removal of ca 70% of the terminal rhamnose the remaining polysaccharide showed a decrease in 1,2,4-branched mannose and an increase in 1,2-linked mannose indicating that at least half of the rhamnose residues were linked to mannose via C-4. GF3 (Mr 40,000) consisted of 1,4-linked galacturonic (30%) and glucuronic (16) acid, 1,3,6-branched galactose (15%), 1,2-linked (5%) and 1,2,4-branched (3.5%) rhamnose as well as 1,5-linked arabinose (11%). Rhamnose (5%) and arabinose (10%) were present as terminal groups. Mild acid hydrolysis selectively cleaved arabinose and the remaining polysaccharide showed an increased amount of 1,6-linked and terminal galactose and a decreased quantity of 1,3,6-branched galactose. These results indicated that the terminal as well as the 1,5-linked arabinose were mainly connected to galactose via C-3. The GF3 polysaccharide appeared to be a rhamnogalacturonan with arabinogalactan side chains.     

Structure of the exocellular D-glucan produced by Neisseria polysaccharea

Neisseria polysaccharea (LNP 462, NCTC 11858), proposed as a prototype strain constituting a new taxon in the genus Neisseria, produces copious amounts of polysaccharide when grown on agar containing 1-5% sucrose. Plate-grown cells produced an exocellular polysaccharide which was composed of D-glucose, had [alpha]D +222 degrees (water), and was shown from composition, specific optical rotation, methylation, enzymic hydrolysis, and 13C nuclear magnetic resonance studies to have an amylopectinlike structure containing mainly 1,4-linked alpha-D-glucopyranosyl residues, but also containing ca. 6% 4,6-di-O-substituted alpha-D-glucopyranosyl branch points.     

Antiangiogenic effects of GFP08, an agaran-type polysaccharide isolated from Grateloupia filicina

An agaran-type polysaccharide, GFP08, isolated from Grateloupia filicina (C. Agardh) Lamouroux, was mainly composed of 1,3-linked β-d-galactose partially sulfated at position O-2 and 1,4-linked α-l-galactose O-2, O-3-disulfate, α-l-galactose O-6-sulfate and 3,6-anhydro-α-l-galactose. Small quantities of xylose, 4,6-O-(1'-carboxyethylidene) and 6-O-methyl-β-d-galactose were also present. In mice bearing sarcoma-180 cells, GFP08 decreased tumor weight in a dose-dependent manner. The antiangiogenic activity of GFP08 was evaluated using the chicken chorioallantoic membrane assay, and the results showed that GFP08 dose-dependently reduced new vessel formation. Meanwhile, GFP08 inhibited the differentiation of human umbilical vein endothelial cells (HUVECs) into capillary-like structures in vitro and reduced the number of migrated cells. However, there was no observed cytotoxicity of GFP08 toward HUVECs. Further study revealed that GFP08 decreased tissue factor (TF) expression without affecting the activities of matrix metalloproteinase-2 and -9. All those data indicated that GFP08 had an antitumor effect that might be associated in part with its antiangiogenic effect through down-regulating the expression of TF protein.     

STRUCTURE OF EXTRACELLULAR POLYSACCHARIDES PRODUCED BY A SOIL CRYPTOMONAS SP. (CRYPTOPHYCEAE)1

The Hindak strain of a Cryptomonas species (Cryptophyceae) produces extracellular polysaccharides. Because there is no information on the structure of these compounds in the Cryptophyceae we conducted structural studies. Gas–liquid chromatographic analyses showed that the polysaccharide is composed of fucose, rhamnose, xylose, mannose, glucose, galactose, galacturonic acid, glucuronic acid, and traces of 3-O-methyl galactose. The polysaccharide was separated into two subtractions by ion-exchange chromatography. Fraction A consisted mainly of 1,3-linked galactose units and 1,4-linked galacturonic acid. Unlike fraction B, fraction A did not have xylose, 3-O-methyl galactose, or glucuronic acid. Also, its degree of branching was low compared to that of fraction B. Only traces of sulfate were present infraction A, but fraction B was 10–15% sulfated. Protein was approximately 1% in both fractions. These polysaccharides appear to be a novel type of polymer in algae.     

Prion rods contain an inert polysaccharide scaffold

A polysaccharide consisting of mainly 1,4-linked glucose units was found associated with prion rods, which are composed mainly of insoluble aggregates of the N-terminally truncated prion protein (PrP 27-30) exhibiting the ultrastructural and tinctorial properties of amyloid. The polysaccharide differs in composition from the Asn-linked oligosaccharides and the GPI-anchor of the prion protein. Prion rods were prepared from scrapie-infected hamster brains using two different purification protocols. Prolonged digestion of rods with proteinase K reduced PrP by a factor of at least 500, leaving about 10% (w/w) of the sample as an insoluble remnant. Only glucose was obtained by acid hydrolysis of the remnant and methylation analysis showed 80% 1,4-, 15% 1,6- and 5% 1,4,6-linked glucose units. The physical and chemical properties as well as the absence of terminal glucose units indicate a very high molecular mass of the polysaccharide. No evidence was found for covalent bonds between PrP and the polysaccharide. The polysaccharide certainly contributes to the unusual chemical and physical stability of prion rods, acting like a scaffold. A potential structural and/or functional relevance of the polysaccharide scaffold is discussed.     

云芝子实体多糖(CVP)化学结构的研究III.*

通过化学、IR和UV光谱等方法发现云芝子实体的热水提取物 CVP 是由多糖、核酸和蛋白质等组成的混合物。通过柱层析方法从 CVP 中纯化出一个多糖组份 B-2-3,经完全水解证实组成它的单糖残基主要为Glc。用 HPLC 方法测得其分子量为 5.01×105。通过对甲基化及 1H 和 13C NMR 数据的分析发现 B-2-3 为一个以β-D-1, 4-Glc、β-D-1, 3-Glc 和β-D-1, 6-Glc 残基构成主链,同时在β-D-1, 3, 6-Glc 及β-D-1, 4, 6-Glc 处产生分枝的多糖。     

Polysaccharide lyases: recent developments as biotechnological tools

Polysaccharide lyases, which are polysaccharide cleavage enzymes, act mainly on anionic polysaccharides. Produced by prokaryote and eukaryote organisms, these enzymes degrade (1,4) glycosidic bond by a beta elimination mechanism and have unsaturated oligosaccharides as major products. New polysaccharides are cleaved only by their specific polysaccharide lyases. From anionic polysaccharides controlled degradations, various biotechnological applications were investigated. This review catalogues the degradation of bacterial, plant and animal polysaccharides (neutral and anionic) by this family of carbohydrate acting enzymes.     

Structure elucidation and antioxidant activity of a novel polysaccharide isolated from Boletus speciosus Forst

In this study, a novel heteropolysaccharide was isolated from the fruiting bodies of Boletus speciosus Forst through DEAE-cellulose column and Sephadex G-200 column. The Boletus speciosus Forst polysaccharide (BSFP-1) had a molecular weight of 1.33×10(4) Da and was mainly composed of l-Man and d-Gal which ratios were 2:1. Structural features of Boletus speciosus Forst polysaccharide (BSFP-1) were investigated by a combination of total hydrolysis, methylation analysis, gas chromatography-mass spectrometry (GC-MS), infrared (IR) spectra and nuclear magnetic resonance (NMR) spectroscopy. The results indicated that Boletus speciosus Forst polysaccharide (BSFP-1) had a backbone of (1→4)-α-l-mannopyranose residues which branches at O-6 based on the experimental results. The branches were mainly composed of one with →1)-α-d-galactopyranose residue. The antioxidant activity of BSFP-1 was evaluated with two biochemical methods, including 1,1-diphenyl-2-picrylhydrazyl (DPPH(-)) radical scavenging, scavenging activity of 2,2'-azino-bis(3-ethylbenzthiazoline-6-suphonic acid)diammonium (ABTS(+)) radical. The results indicated that BSFP-1 showed strong antioxidant.     

Detailed Structure of an Acidic Polysaccharide in Soy Sauce,Confirmed by Use of Two Kinds of Purified Pectinases

The partially degraded polysaccharide obtained by means of mild acid hydrolysis of APS–I, an acidic polysaccharide in soy sauce, was incubated with an endo-polygalacturonase, and some acidic sugars liberated were fractionated and purified from the enzymatic hydrolyzate. They were identified as d-galacturonic acid (Gal A), its α-l,4-linked dimer and trimer, d-xylose (Xyl) β1→3 Gal A and Xyl β1→3 Gal A α1→4 Gal A, and an acidic polymer composed of the above-mentioned sugars through methylation analysis and other methods.

Methyl-esterized APS–I was subjected to β-elimination with pectin lyase or by heat treatment. The high molecular fraction which was highly resistant to β-elimination, was concluded to be β-1,4-linked d-galactan of which reducing-end group was attached to d-galacturonic acid. On the basis of these findings and previous knowledges, the construction of APS–I was also discussed.     

Rheological investigation of synergistic interactions between galactomannans and non-pectic polysaccharide fraction from water soluble yellow mustard mucilage

Synergistic interactions between galactomannans (GMs) and non-pectic polysaccharides (NPP) from yellow mustard mucilage were investigated in the present study. Structural analysis revealed that NPP was mainly composed of β-1,4-d glucosidic linkage. Four types of GMs, namely fenugreek gum (FG), guar gum (GG), tara gum (TG) and locust bean gum (LBG) with mannose to galactose ratios (M/G) of 1.2, 1.7, 3.0 and 3.7, respectively, were blended with NPP at various ratios. The viscoelastic properties of the mixtures were measured in order to evaluate the effects of GM/NPP blending ratio, M/G ratio, total polysaccharide concentration and pH on the synergistic interactions. Results revealed that at a total polysaccharide concentration of 0.5% (w/w), the highest synergism occurred at the GM/NPP blending ratio of 3/7 for all four types of GMs. The interaction between TG and NPP showed the highest synergy, followed by LBG/NPP, FG/NPP and GG/NPP. At a higher total polysaccharide concentration (1.0% w/w), the mixture of TG and NPP still exhibited the highest synergy, however, the order of synergy between NPP and other GMs was changed as FG/NPP, LBG/NPP and GG/NPP. At the total polysaccharide concentration of 0.5% and GM/NPP blending ratio of 3/7, neutral pH (pH 6.5) showed the strongest synergy compared to that at pH 2.0 and pH 12.0. The mechanism of the synergistic effects could be explained by a combination of segregative association model and junction zone model.     

A note on the formation of microbial polysaccharide from wheat straw decomposed in the absence of soil

C hapman , S.J. & L ynch , J.M. 1984. A note on the formation of microbial polysaccharide from wheat straw decomposed in the absence of soil. Journal of Applied Bacteriology 56 , 337–342.
The proportions of neutral sugars in fresh and decomposed wheat straw polysaccharide were similar, irrespective of the oxygen concentration used during breakdown. Polysaccharide extracted by hot water from the decomposed straw was composed mainly of galactose, glucose and mannose with smaller quantities of arabinose, xylose, rhamnose, fucose and ribose. The presence of these sugars indicates a mainly microbial origin for the polysaccharide but with some soluble hemi-cellulose breakdown products. The polysaccharide precipitable with 70% (v/v) ethanol accounted for 0.5% (w/w) of the degraded straw. The extracted polysaccharide was shown to increase the aggregate stability of Mount St Helens volcanic ash.     

Role of the synthase domain of Ags1p in cell wall alpha-glucan biosynthesis in fission yeast

The cell wall is important for maintenance of the structural integrity and morphology of fungal cells. Besides beta-glucan and chitin, alpha-glucan is a major polysaccharide in the cell wall of many fungi. In the fission yeast Schizosaccharomyces pombe, cell wall alpha-glucan is an essential component, consisting mainly of (1,3)-alpha-glucan with approximately 10% (1,4)-linked alpha-glucose residues. The multidomain protein Ags1p is required for alpha-glucan biosynthesis and is conserved among cell wall alpha-glucan-containing fungi. One of its domains shares amino acid sequence motifs with (1,4)-alpha-glucan synthases such as bacterial glycogen synthases and plant starch synthases. Whether Ags1p is involved in the synthesis of the (1,4)-alpha-glucan constituent of cell wall alpha-glucan had remained unclear. Here, we show that overexpression of Ags1p in S. pombe cells results in accumulation of (1,4)-alpha-glucan. To determine whether the synthase domain of Ags1p is responsible for this activity, we overexpressed Ags1p-E1526A, which carries a mutation in a putative catalytic residue of the synthase domain, but observed no accumulation of (1,4)-alpha-glucan. Compared with wild-type Ags1p, this mutant Ags1p showed a markedly reduced ability to complement the cell lysis phenotype of the temperature-sensitive ags1-1 mutant. Therefore, we conclude that, in S. pombe, the production of (1,4)-alpha-glucan by the synthase domain of Ags1p is important for the biosynthesis of cell wall alpha-glucan.     

Structural characterization of the O-chain polysaccharide isolated from Bordetella avium ATCC 5086: variation on a theme(1)

The O-chain polysaccharide (O-PS) of Bordetella avium was isolated from the lipopolysaccharide by mild acid hydrolysis to remove the lipid A, followed by hydrofluorolysis to remove the lipopolysaccharide core oligosaccharide leaving a residual O-PS for structural analysis. High resolution (1)H and (13)C NMR and MALDI studies showed the O-chain to be a polymer composed of 1,4-linked 2-acetamidino-3-[3-hydroxybutanamido]-2,3-dideoxy-beta-D-glucopyranosyluronic acid residues.     

银耳碱提孢子多糖A-BTF的分离与结构研究

银耳孢子发酵粉(Tremella fuciformisBerk),用热水煮提后,除去水溶性多糖。其沉淀用1M NaOH提取,Sevage法除去蛋白,用乙醇沉淀得到粗多糖。粗多糖经DEAE-32-cellulose和sephadex G-200反复分离后,纯化得到分布均一的多糖A-BTF。HPGPC测定A-BTF的分子量为67000,糖组成分析显示主要由葡萄糖组成。多糖A-BTF的甲基化产物,经水解、还原、乙酰化,通过GC-MS分析表明,主要含有1,6连接的葡萄糖和1,3,6连接的甘露糖,另外还有1,4连接的葡萄糖少量的半乳糖和1-NH2-来苏糖,末端为端基连接的葡萄糖。     

Isolation and structural characterization of a neutral polysaccharide from the stems of Dendrobium densiflorum

A novel neutral heteropolysaccharide (DDP-1-D) was purified from hot water extracts of dried stem of Dendrobium densiflorum by DEAE-52 and Sephacryl S-200 High-Resolution Chromatography. The heteropolysaccharide had an average molecular weight about 9440 Da. It was composed mainly of glucose and mannose in the ratio of 3.01:1. Structural features of DDP-1-D were elucidated by a combination of chemical and instrumental techniques, including FT-IR, GC-MS, periodate oxidation-Smith degradation, (1)H and (13)C NMR spectroscopies (including COSY, TOCSY, HSQC, and HMBC spectra). The results indicated that DDP-1-D is a mannoglucan and has a backbone consisting of (1→4)-linked α-D-Glcp, (1→6)-linked α-D-Glcp, (1→2)-linked α-D-Manp and (1→4)-linked β-Manp. This is the first study to provide clear evidence for the structure of the polysaccharide in D. densiflorum.     

Structural studies on an antitumor polysaccharide from Microellobosporia grisea

The structure of the antitumor polysaccharide from the actinomycete Microellobosporia grisea has been investigated. By methylation and periodate-oxidation studies, the polysaccharide was shown to consist of (nonreducing)d-mannosyl groups, (1→4)-linkedd-glucosyl residues, and 3,6-branched, (1→4)-linkedd-glucosyl residues in the approximate molar ratios of 2:1:1. Periodate oxidation of the polysaccharide, followed by borohydride reduction and mild hydrolysis with acid yielded glycerol, erythritol, 2-O-β-d-glucopyranosyl-d-erythritol, and 5-O-β-d-glucopyranosyl-2,4-bis(hydroxymethyl)-1,3-dioxane, which were isolated in the molar ratios of 2.0:0.14:0.74:0.35. Partial hydrolysis of the polysaccharide gave α-d-Man p-(1→6)-d-Glcp, β-d-Glcp-(1→4)-d-Glcp, α-d-Man p-(1→3)-d-Glcp, and β-d-Glcp-(1→4)-[α-d-Man p-(1→3)-]-d-Glcp. From these results, it is proposed that the polysaccharide is mainly composed of tetrasaccharide repeating-units having the following structure.     

Functional characterization of PmHS1, a Pasteurella multocida heparosan synthase

Heparosan synthase 1 (PmHS1) from Pasteurella multocida Type D is a dual action glycosyltransferase enzyme that transfers monosaccharide units from uridine diphospho (UDP) sugar precursors to form the polysaccharide heparosan (N-acetylheparosan), which is composed of alternating (-alpha4-GlcNAc-beta1,4-GlcUA-1-) repeats. We have used molecular genetic means to remove regions nonessential for catalytic activity from the amino- and the carboxyl-terminal regions as well as characterized the functional regions involved in GlcUA-transferase activity and in GlcNAc-transferase activity. Mutation of either one of the two regions containing aspartate-X-aspartate (DXD) residue-containing motifs resulted in complete or substantial loss of heparosan polymerizing activity. However, certain mutant proteins retained only GlcUA-transferase activity while some constructs possessed only GlcNAc-transferase activity. Therefore, it appears that the PmHS1 polypeptide is composed of two types of glycosyltransferases in a single polypeptide as was found for the Pasteurella multocida Type A PmHAS, the hyaluronan synthase that makes the alternating (-beta3-GlcNAc-beta1,4-GlcUA-1-) polymer. However, there is low amino acid similarity between the PmHAS and PmHS1 enzymes, and the relative placement of the GlcUA-transferase and GlcNAc-transferase domains within the two polypeptides is reversed. Even though the monosaccharide compositions of hyaluronan and heparosan are identical, such differences in the sequences of the catalysts are expected because the PmHAS employs only inverting sugar transfer mechanisms whereas PmHS1 requires both retaining and inverting mechanisms.     

Structural analysis and antiviral activity of a sulfated galactan from the red seaweed Schizymenia binderi (Gigartinales, Rhodophyta)

Aqueous extraction of gametophytic Schizymenia binderi afforded a polysaccharide composed of galactose and sulfate groups in a molar ratio of 1.0:0.89 together with uronic acids (6.8 wt%) and minor amounts of other neutral sugars. Alkali-treatment of the polysaccharide afforded a polysaccharide devoid of 3,6-anhydrogalactose. 13C NMR spectroscopy of the desulfated alkali-treated polysaccharide showed a backbone structure of alternating 3-linked beta-D-galactopyranosyl and 4-linked alpha-galactopyranosyl units that are predominantly of the D-configuration and partly of the L-configuration. Methylation, ethylation and NMR spectroscopic studies of the alkali-treated polysaccharide indicated that the sulfate groups are located mainly at positions O-2 of 3-linked beta-D-galactopyranosyl residue and at position O-3 of 4-linked-alpha-galactopyranosyl residues, the latter is partially glycosylated at position O-2. The sulfated galactan from S. binderi exhibited highly selective antiviral activity against Herpes simplex virus types 1 and 2, with selectivity indices (ratio cytotoxicity/antiviral activity) >1000 for all assayed virus strains. This compound was shown to interfere with the initial adsorption of viruses to cells.