首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
An anticoagulant fucoidan from the brown seaweed Ecklonia kurome.   总被引:5,自引:0,他引:5  
The structure of a alpha-L-fucose-rich, sulphated polysaccharide (C-I) with a potent anticoagulant activity, which was isolated from the brown seaweed Ecklonia kurome, has been studied. Methylation analysis showed that C-I consisted mainly of 3-linked and 3,4-disubstituted fucopyranosyl residues in addition to non-reducing terminal fucofuranosyl and fucopyranosyl residues, 2,3-di- and 2,3,4-tri-substituted fucopyranosyl residues and galactopyranosyl residues with various glycosidic linkages. Methanolysis of C-I gave neutral di-, tri-, tetra- and highly polymerized-oligosaccharide fractions. GC-MS and methylation analysis indicated that di- and trisaccharide fractions consisted mainly of Fuc-(1----3)-Fuc and Fuc-(1----3)-Fuc-(1----3)-Fuc, respectively, in addition to small amounts of Fuc-(1----4)-Fuc, Fuc-(1----4)-Gal and Fuc-(1----3)-[Fuc-(1----2)-]Fuc. When methylated C-I was subjected to methanolysis for desulphation followed by remethylation with deuterated methyl iodide, most of deuteriomethyl groups substituted to position 4 of 3-linked Fuc.  相似文献   

2.
A fucoidan, a heterogeneous sulfated polysaccharide from the brown alga Fucus evanescens, was depolymerized under solvolytic conditions, and its ethanol-extracted low-molecular-weight fraction was analyzed by MALDI-TOFMS and ESIMS/MS. It was found that the mixture contained unsulfated oligosaccharides including some monosulfated components, which were shown to consist of mainly (1→3)-linked 2-O-sulfonated fucose residues (from 1 to 4). Minor components of the mixture were shown to contain 2-O- and 4-O-sulfonated xylose and galactose residues. Among them, mixed monosulfonated fucooligosaccharides were detected and characterized: Xyl-(1→4)-Fuc, Gal-(1→4)-Fuc, Gal-(1→4)-Gal-(1→4)-Fuc, Gal-(1→4)-Gal. Fucose, galactose, and xylose residues were shown to be mainly 2-O-sulfonated with traces of 4-O-sulfonation. Glucuronic acid was also found as a part of non-sulfated fucooligosaccharides: Fuc-(1→3)-GlcA, Fuc-(1→4)-Fuc-(1→3)-GlcA, Fuc-(1→3)-Fuc-(1→4)-Fuc-(1→3)-GlcA.  相似文献   

3.
A mouse IgM monoclonal antibody, ACFH-18, was established after immunization of mice with the human gastric cancer cell line MKN74. The antibody reacts strongly with gastrointestinal carcinoma and showed a clear dependence on the degree of differentiation of gastric cancer cells. The antibody defines a series of glycolipid species with extremely slow TLC mobility present in both acidic and neutral glycolipid fractions of the extract from gastrointestinal adenocarcinoma and the original MKN74 cells. Isolation and structural study of the active glycolipids present in the acidic and neutral fractions and comparison of the antibody reactivity with glycolipids having related structures revealed a novel specificity. The minimum requirement for the maximal reactivity of ACFH-18 was identified as VII3Fuc-nLc10 (Structure A below and Fig. 8 in text). Since the antibody did not react with III3Fuc-nLc6 (Structure B below), which shares the same terminal sequence as VII3Fuc-nLc10, and since it cross-reacted with VII3Fuc-nLc8 (Z1 glycolipid) and VII3Fuc,V3-Fuc,III3Fuc-nLc8 (Z3 glycolipid), antibody ACFH-18 is capable of recognizing a fucosyl residue plus an internal repeating N-acetyllactosamine proximal to ceramide, as indicated by lines in Fig. 8 (Structures A, B, and E-G). (Formula: see text).  相似文献   

4.
T Endo  D Groth  S B Prusiner  A Kobata 《Biochemistry》1989,28(21):8380-8388
Prion proteins from humans and rodents contain two consensus sites for asparagine-linked glycosylation near their C-termini. The asparagine-linked oligosaccharides of the scrapie isoform of the hamster prion protein (PrP 27-30) were released quantitatively from the purified molecule by hydrazinolysis followed by N-acetylation and NaB3H4 reduction. The radioactive oligosaccharides were fractionated into one neutral and three acidic oligosaccharide fractions by anion-exchange column chromatography. All oligosaccharides in the acidic fractions could be converted to neutral oligosaccharides by sialidase digestion. Structural studies on these oligosaccharides including sequential exoglycosidase digestion in combination with methylation analysis revealed that PrP 27-30 contains a mixture of bi-, tri-, and tetraantennary complex-type sugar chains with Man alpha 1----6(GlcNAc beta 1----4)(Man alpha 1----3)Man beta 1----4GlcNAc beta 1----4-(Fuc alpha 1----6)GlcNAc as their core. Variation is produced by the different combination of the oligosaccharides Gal beta 1----4GlcNAc beta 1----, Gal beta 1----4(Fuc alpha 1----3)GlcNAc beta 1----, GlcNAc beta 1----, Sia alpha 2----3Gal beta 1----4GlcNAc beta 1----, and Sia alpha 2----6Gal beta 1----4GlcNAc beta 1---- in their outer chain moieties. When both asparagine-linked consensus sites are glycosylated, the diversity of oligosaccharide structures yields over 400 different forms of the scrapie prion protein. Whether these diverse asparagine-linked oligosaccharides participate in scrapie prion infectivity or modify the function of the cellular prion protein remains to be established.  相似文献   

5.
Alkaline phosphatase purified from human placenta contains a single asparagine-linked sugar chain in one molecule. The sugar chain was quantitatively liberated as radioactive oligosaccharides from the polypeptide moiety by hydrazinolysis followed by N-acetylation and NaB3H4 reduction, and separated by paper electrophoresis into one neutral and two acidic fractions. By a combination of sequential exoglycosidase digestion and methylation analysis, the structures of oligosaccharides in the neutral fraction were confirmed to be as follows: Gal beta 1----4GlcNAc beta 1----2Man alpha 1----6(Gal beta 1----4GlcNAc beta 1----2Man alpha 1----3)Man beta 1----4GlcNAc beta 1----4(+/- Fuc alpha 1----6)GlcNAc. The acidic oligosaccharide fractions were mixtures of mono- and disialyl derivatives of the neutral fraction. All the sialic acid residues of the sugar chains occur as the NeuAc alpha 2----3Gal group. In the case of monosialyl derivatives, the N-acetylneuraminic acid was exclusively linked to the Man alpha 1----3 arm.  相似文献   

6.
Two key synthons for the title pentasaccharide derivative, methyl O-(methyl 2-O-benzoyl-3-O-benzyl-alpha-L-idopyranosyluronate)-(1----4)-6-O-acetyl- 2-azido - 3-O- benzyl-2-deoxy-beta-D-glucopyranoside and O-(methyl 2,3-di-O-benzyl-4-O- chloroacetyl-beta-D-glucopyranosyluronate)-(1----4)-3,6-di-O-acetyl-2-az ido-2- deoxy-alpha-D- glucopyranosyl bromide, were prepared from a common starting material, cellobiose. They were coupled to give a tetrasaccharide derivative that underwent O-dechloroacetylation to the corresponding glycosyl acceptor. Its condensation with the known 6-O-acetyl-2-azido-3,4-di-O-benzyl-2-deoxy-alpha-D-glucopyranosyl bromide afforded a 77% yield of suitably protected pentasaccharide, methyl O-(6-O- acetyl-2-azido-3,4-di-O-benzyl-2-deoxy-alpha-D-glucopyranosyl)-(1----4)- O- (methyl 2,3- di-O-benzyl-beta-D-glucopyranosyluronate)-(1----4)-O-(3,6-di-O-acetyl-2- azido-2 - deoxy-alpha-D-glucopyranosyl)-(1----4)-O-(methyl 2-O-benzoyl-3-O-benzyl-alpha-L- idopyranosyluronate)- (1----4)-6-O-acetyl-2-azido-3-O-benzyl-2-deoxy-beta-D-glucopyranoside. Sequential deprotection and sulfation gave the decasodium salt of methyl O-(2- deoxy-2-sulfamido-6-O-sulfo-alpha-D-glucopyranosyl)-(1----4)-O-(be ta-D- glucopyranosyl-uronic acid)-(1----4)-O-(2-deoxy-2-sulfamido-3,6-di-O-sulfo-alpha-D-gluco pyranosyl)- (1----4)-O-(2-O-sulfo-alpha-L-idopyranosyluronic acid)-(1----4)-2-deoxy-2- sulfamido-6-O- sulfo-beta-D-glucopyranoside (3). In a similar way, the trisaccharide derivative, the hexasodium salt of methyl O-(2-deoxy-2-sulfamido-6-O-sulfo-alpha-D- glucopyranosyl)- (1----4)-O-(beta-D-glucopyranosyluronic acid)-(1----4)-2-deoxy-2-sulfamido-3,6- di-O- sulfo-alpha-D-glucopyranoside (4) was synthesized from methyl O-(6-O-acetyl-2- azido- 3,4-di-O-benzyl-2-deoxy-alpha-D-glucopyranosyl)-(1----4)-O-(methyl 2,3-di-O- benzyl-beta- D-glucopyranosyluronate)-3,6-di-O-acetyl-2-azido-2-deoxy-alpha-D- glucopyranoside. The pentasaccharide 3 binds strongly to antithrombin III with an association constant almost equivalent to that of high-affinity heparin, but the trisaccharide 4 appears not to bind.  相似文献   

7.
Purified glycolipids were tested for their ability to serve as acceptors of [14C]fucose from GDP-[14C]fucose as catalyzed by cell-free extracts and purified membrane fractions of human colorectal carcinoma cells, SW1116, cultured in serum-free medium. Purified lactotetraosyl ceramide (Gal beta 1----3GlcNAc beta 1----3Gal beta 1----4Glc-Cer or LcOse4Cer) and H-1 glycolipid (Fuc alpha 1----2Gal beta 1----3GlcNAc beta 1----3Gal beta 1----4Glc-Cer or IV2 Fuc alpha LcOse4Cer) stimulated incorporation of radioactivity into lipid-soluble glycolipid at a rate greater than ten times that of Lea glycolipid [Gal beta 1----3(Fuc alpha 1----4)GlcNAc beta 1----3Gal beta 1----4Glc-Cer or III4 Fuc alpha LcOse4Cer]. The enzymatic activities in crude and purified membrane fractions were optimized for substrate concentrations (glycolipid and GDP-fucose), detergent requirement (taurocholate), pH, time and protein. The radioactive product of H-1 fucosylation migrated as discrete and distinct bands on high-performance thin-layer chromatograms (HPTLC). Evidence for their identity with Leb fucolipid described previously [Fuc alpha 1----2Gal beta 1----3(Fuc alpha 1----4)GlcNAc beta 1----3Gal beta 1----4Glc-Cer or III4IV2 (Fuc alpha) LcOse4Cer] is presented. The radioactive product of LcOse4Cer fucosylation was mainly Lea fucolipid as determined by co-migration with authentic Lea fucolipid in three HPTLC systems as native and acetylated derivatives. Our results also indicated a low level of H-1 and Leb glycolipid synthesis from LcOse4Cer. On the basis of the optima, linearity for time, and enzyme-limiting conditions, we obtained a 12-19-fold purification of the LcOse4Cer and H-1 fucosyl transferase acceptor activities in three peaks of a sucrose gradient. The peak with the highest specific activity (peak 3) was highest in density and in Na+, K+, ATPase specific activity, although NADH-cytochrome-c reductase and UDP-GalNac transferase were also present in peak 3. The apparent Km values of LcOse4Cer acceptor activity and H-1 acceptor activity in peak 3 were significantly different (p less than 0.01) by statistical tests, 2.4 microM and 0.5 microM, respectively. These apparent Km values were much lower (10(3) X) and the pH optima were lower (4.8-5.3), than the corresponding properties reported for the alpha 1----3/alpha 1----4 fucosyl transferase purified from human milk. Our results suggest a role for the non-glycosidic moieties of the acceptors and/or the tissue-specific or primitive expression of these fucosyl transferase activities.  相似文献   

8.
Mono- and two-dimensional 1H-NMR allowed the structural elucidation of a glycolipid belonging to the phenolic mycosides series: 2,3,4-tri-0-methyl fucopyranosyl (alpha 1----3) rhamnopyranosyl (alpha 1----3) rhamnopyranosyl (alpha 1----dimycocerosyl) phenol phthiocerol. It shares with the major phenolic glycolipid the two terminal sugar residues, suggesting its potential antigenicity. The glycolipid may also represent an intermediate in the biosynthesis of the major one.  相似文献   

9.
The structure of a unique focose-branched chondroitin sulfate isolated from the body wall of a sea cucumber was examined in detail. This glycosaminoglycan contains side chain disaccharide units of sulfated fucopyranosyl units linked to approximately one-half of the glucuronic acid moieties through the O-3 position of the acid. The intact polysaccharide is totally resistant to chondroitinase degradation, whereas, after defucosylation, it is partially degraded by the enzyme. However, only after an additional step of desulfation, the chondroitin from sea cucumber is almost totally degraded by chondroitinase AC or ABC. This result, together with the methylation and NMR studies of the native and chemically modified polysaccharide, suggest that besides the fucose branches, the sea cucumber chondroitin sulfate contains sulfate esters at position O-3 of the beta-D-glucuronic acid units. Furthermore, the proteoglycan from the sea cucumber chondroitin sulfate is recognized by anti-Leu-7 monoclonal antibody, which specifically recognizes 3-sulfoglucuronic acid residues. In analogy with the fucose branched units, the 3-O-sulfo-beta-D-glucuronosyl residues are resistant to chondroitinase degradation. Regarding the position of the glycosidic linkage and site of sulfation in the fucose branches, our results suggest high heterogeneity. Tentatively, it is possible to suggest the preponderance of disaccharide units formed by 3,4-di-O-sulfo-alpha-L-fucopyranosyl units glycosidically linked through position 1----2 to 4-O-sulfo-alpha-L-fucopyranose. Finally, the presence of unusual 4/6-disulfated disaccharide units, together with the common 6-sulfated and non-sulfated units, was detected in the chondroitin sulfate core of this polysaccharide.  相似文献   

10.
Sulfated fucans, the complex polysaccharides from brown seaweeds, possess various biological activities. To understand the structure activity relationship of sulfated fucans, we have investigated the structural features of one such polymer from Padina tetrastromatica using standard methods of carbohydrate structural analysis. We report a novel structural motif for this polymer. The average structure of this macromolecule that has a molecular mass of 25 kDa differs from the previous models in three respects. First, the core region of this macromolecule is composed primarily of α-(1 → 2)- and α-(1 → 3)-linked fucopyranosyl residues. Sulfate groups, when present are located at position 4 and 2 of fucosyl residues. Secondly, fucose and xylose is attached to this polymer to form branch points, one for every two residues within the chain. Finally, this macromolecule contained smaller amount of sulfate (0.21 mol of sulfate per mol of deoxyhexose).  相似文献   

11.
Acid-soluble and alkali-insoluble glucan fractions were prepared from yeast, hyphal and germ-tube forming cells of Candida albicans. Alkali-insoluble glucan was also extracted from purified yeast cell walls. Paper chromatography of partial acid hydrolysates confirmed that the glucan preparations contained beta(1----3)- and beta(1----6)-chains but no mixed intra-chain beta(1----3)/(1----6) linkages. Methylation and 13C-NMR analyses showed that the acid-soluble glucan consisted of a highly branched polymer composed mainly (67.0% to 76.6%) of beta(1----6)-linked glucose residues. The alkali-insoluble glucan from yeast and hyphal cells contained from 29.6% to 38.9% beta(1----3) and 43.3% to 53.2% beta(1----6) linkages. Alkali-insoluble glucan from germ-tube forming cells consisted of 67.0% beta(1----3) and 14% beta(1----6) linkages. Branch points accounted for 6.7%, 12.3% and 17.4% of the residues in the alkali-insoluble glucan of yeast, germ-tube forming and hyphal cells, respectively.  相似文献   

12.
N-Phthaloylation of lactosamine gave various glycosyl donors (beta-chloride, beta-trichloroacetimidate) and glycosyl acceptors (3',4'-diol). Coupling of the chloride with a methyl beta-D-glycoside led to the tetrasaccharide fragment, beta-D-Galp-(1----4)-beta-D-GlcpNac-(1----3)-beta-D-Galp-(1----4)- beta-D-GlcpNAcOMe. Acetolysis of the protected tetrasaccharide, followed by treatment with hydrogen chloride, gave a tetrasaccharide chloride which was coupled with the methyl beta-glycoside of lactosamine. A hexasaccharide fragment, [beta-D-Galp-(1----4)-beta-D-GlcpNAc-(1----3)]2-beta-D-Galp-(1----4)-bet a- D-GlcpNAcOMe, was thus obtained by this ("n + 1") method. A more efficient ("n + n") method was applied for the synthesis of an octasaccharide fragment, [beta-D-Galp-(1----4)-beta-D-GlcpNAc-(1----3)]3-beta-D-Galp- (1----4)-beta-D-GlcpNAcOMe (38), where di- and tetra-saccharide intermediates having a 3,4-O-isopropylidene-beta-D-galactopyranosyl nonreducing terminal group and a benzyl beta-D-glycoside group were precursors, either as glycosyl donors (beta-trichloroacetimidates) or glycosyl acceptors (3,4-diols as nonreducing terminal groups). Thus, doubling the length of the repetitive oligosaccharide sequence could be efficiently accomplished at each glycosylation step.  相似文献   

13.
400 MHz NMR spectrum was recorded for the glycoprotein -bound large carbohydrates (embryoglycan) isolated from F9 embryonal carcinoma cells. Two intense signals at 4.13 ppm and 4.69 ppm were assigned to be H-4 of galactosyl residues substituted at C-3 and H-1 of G1cNAc beta 1----3, respectively. The result is consistent with the proposal that the fundamental building unit of the large glycan is G1cNAc beta 1----3Ga1 beta. Furthermore, the spectral data confirmed a conclusion obtained by glycosidase digestion that fucosyl residues are linked mostly to N-acetylglucosamine rather than galactose.  相似文献   

14.
Caulobacters are adherent prosthecate bacteria that are members of bacterial biofouling communities in many environments. Investigation of the cell surface carbohydrates produced by two strains of the freshwater Caulobacter crescentus, CB2A and CB15A, revealed a hitherto undetected extracellular polysaccharide (EPS) or capsule. Isolation and characterization of the EPS fractions showed that each strain produced a unique neutral EPS which could not be readily removed from the cell surface by washing. Monosaccharide analysis showed that the main CB2A EPS contained D-glucose, D-gulose, and D-fucose in a ratio of 3:1:1, whereas the CB15A EPS fraction contained D-galactose, D-glucose, D-mannose, and D-fucose in approximately equal amounts. Methylation analysis of the main CB2A EPS showed the presence of terminal glucose and gulose groups, 3-linked fucosyl, and two 3,4-linked glucosyl units, thus confirming the pentasaccharide repeating unit indicated by 1H nuclear magnetic resonance analysis. Similar studies of the CB15A EPS revealed a tetrasaccharide repeating unit consisting of terminal galactose, 4-linked fucosyl, 3-linked glucosyl, and 3,4-linked mannosyl residues. EPS was not detectable by thin-section electron microscopy techniques, including some methods designed to preserve or enhance capsules, nor was the EPS readily detected on the cell surface by scanning electron microscopy when conventional fixation techniques were used; however, a structure consistent with EPS was revealed when samples were prepared by cryofixation and freeze-substitution methods.  相似文献   

15.
Two types of fucan sulfate were isolated from chloroform/methanol extract of the body wall of the sea cucumber Stichopus japonicus. One type (type A) contained 3.41 mmol fucose/g and 2.35 mmol sulfate/g, and the molecular mass was determined to be 9 kDa by gel permeation chromatography (GPC). Structural analysis suggested that type A consists of a backbone of (1-->3)-linked fucosyl residues that are substituted at C-4 with fucosyl residues, and that fucosyl residues are sulfated at C-2 and/or C-4. Another type (type B) contained 3.90 mmol fucose/g and 3.07 mmol sulfate/g, and the molecular mass was determined to be 32kDa by GPC. Structural analysis showed that type B is largely composed of unbranched (1-->3)-linked fucosyl residues, and that sulfate substitution(s) occur at C-2 and/or C-4. The potential of both types to inhibit osteoclastogenesis was examined by an in vitro assay system, showing that both types of fucan sulfate inhibit osteoclastogenesis more than 95% at 50 microg/mL concentration. These results suggest that types A and B fucan sulfate from sea cucumber are potent inhibitors of osteoclastogenesis.  相似文献   

16.
In a comparative study of acidic glycosphingolipids in the small intestine of several species it was found that the mouse contained a complex sulfoglycolipid as a major component (Breimer, M.E., Hansson, G.C., Karlsson, K.-A., and Leffler, H. (1983) J. Biochem. (Tokyo) 93, 1473-1485). Fast atom bombardment negative ion mass spectrometry proved the presence and location of the sulfate group and also showed the saccharide sequence and ceramide composition. Combined with NMR spectroscopy of the intact structure and degradative studies the structure was shown to be -O3SO----3Galp beta 1----3GalNAcp beta 1----4Galp beta 1----4Glcp beta 1----1Cer. The sulfoglycolipid was enriched in epithelial cells of mouse small intestine where it constituted at least 90% of the acidic glycolipids and 4-8 mol% of the total glycosphingolipids.  相似文献   

17.
Sialylated fucosyl lactosaminoglycan was isolated from human neutrophilic granulocytes and its structure was elucidated. The lactosaminoglycan glycopeptides were digested by endo-beta-galactosidase and "the core portion" and released oligosaccharides were analyzed by permethylation, fast atom bombardment mass spectrometry, and exoglycosidases. In addition, lactosaminoglycan saccharides were obtained by hydrazinolysis and the structures of fractionated sialyl oligosaccharides were analyzed by fast atom bombardment mass spectrometry and permethylation coupled with exoglycosidase treatment. The structure of one of the major components was found to be: (Formula: see text). This structure is unique in that 1) four linear polylactosaminyl side chains are attached to the core portion, 2) the side chain arising from position 4 of 2,4-linked mannose contains one or more alpha 1----3 fucosyl residues, 3) the side chain arising from position 6 of 2,6-linked mannose is terminated with NeuNAc alpha 2----3Gal(Fuc alpha 1----3)GlcNAc, sialyl Lex, and 4) the side chain arising from position 2 of 2,4-linked mannose is terminated with sialic acid through alpha 2----6 linkage.  相似文献   

18.
The galactofucan sulfate extract (GFS) obtained from the brown seaweed Undaria pinnatifida by extraction with dilute acid is a potent inhibitor of the herpes viruses HSV-1, HSV-2 and HCMV, with IC50 values determined in vitro of 1.1, 0.2 and 0.5 μgmL−1, respectively. Fractionation of GFS by anion exchange chromatography gave three fractions which differed in their uronic acid and sulfate contents and in their antiviral activity, as well as in having somewhat reduced molecular weights compared to GFS. The low uronic acid/high sulfate fraction (F2M), obtained in 63% yield, had similar molar proportions of galactopyranosyl and fucopyranosyl residues, little associated protein and was equipotent with GFS (IC50 values of 1.1, 0.1 and 0.5 μgmL−1, respectively). The high uronic acid/low sulfate fraction (F1M), obtained in 18% yield, had a much lower proportion of galactopyranosyl residues and was less active (IC50 values of 4.6, 1.0 and 4.0 μgmL−1, respectively). The minor low uronic acid/high sulfate fraction (F4M) had a significant amount of associated protein and was also less active (IC50 = 3.1, 1.0 and 2.0 μgmL−1, respectively). The structure of the major fraction (F2M) was shown to be complex by glycosyl linkage analysis before and after solvolytic desulfation, with many component sugar residues being identified, although 3-linked fucopyranosyl 2,4-disulfate residues were a prominent feature.  相似文献   

19.
alpha-L-Fucosidase was purified from human liver to apparent homogeneity and subjected to exhaustive digestion with Pronase. The resulting glycopeptides were isolated by gel filtration on Sephadex G-50 and further fractionated by Bio-Gel P-4 chromatography. Five glycopeptide fractions were obtained. The structures of the carbohydrate portions of all glycopeptide components were fully characterized by a combination of 500-MHz 1H NMR spectroscopy and carbohydrate composition analysis. Fraction I contained disialyl diantennary glycopeptides of the N-acetyllactosamine type. Fractions II and III contained predominantly mono(sialyl-N-acetyllactosaminyl) diantennary glycopeptides with the NeuAc alpha(2----6)Gal beta(1----4)GlcNAc beta(1----2) branch attached to alpha(1----3)-linked Man in II and to alpha(1----6)-linked Man in III. The N-acetyllactosamine-type glycopeptides in fractions I to III have a small portion (10-15%) of their Asn-linked GlcNAc residues substituted by additional alpha(1----6)-linked Fuc. Also, a minor portion of the NeuAc residues appeared to be attached to Gal in alpha(2----3) rather than alpha(2----6) linkage. Fraction IV contained a mixture of larger-size oligomannoside-type glycopeptides with a variable number (6 to 9) of Man residues. Smaller-size oligomannoside-type glycopeptides were found in fraction V, containing 3 or 5 Man residues; a small portion (10%) of the Man3GlcNAc2Asn component appeared to contain in addition a Fuc residue in alpha(1----6) linkage to the Asn-bound GlcNAc. The overall ratio of oligomannoside-type to N-acetyllactosamine-type carbohydrate structures was found to be 5:4. This article is the first account of the complete characterization of the oligomannoside-type structures in alpha-L-fucosidase; furthermore, the occurrence in alpha-L-fucosidase of mono(sialyl-N-acetyllactosaminyl) structures, Fuc-containing oligosaccharides, and NeuAc alpha(2----3) linked to Gal are reported for the first time.  相似文献   

20.
gamma-Glutamyltranspeptidase purified from human kidneys contains 4-5 asparagine-linked sugar chains in each molecule. The sugar chains were released from the polypeptide portion of the enzyme by hydrazinolysis as oligosaccharides and separated by paper electrophoresis into one neutral and two acidic fractions. By sequential exoglycosidase digestion and methylation analysis, the neutral fraction, which comprised 69% of total oligosaccharides, was shown to be a mixture of bisected bi- and triantennary complex-type sugar chains with and without a fucose on the proximal N-acetylglucosamine residue and with Gal beta 1----4GlcNAc and/or Gal beta 1----4(Fuc alpha 1----3)GlcNAc groups in their outer chain moieties. The acidic oligosaccharide fractions were mixtures of mono- and disialyl derivatives of bisected triantennary complex-type oligosaccharides with Gal beta 1----4GlcNAc and/or Gal beta 1----4(Fuc alpha 1----3)GlcNAc group in their outer chain moieties. Some of the outer chains of the acidic oligosaccharides were considered to be sialylated X-antigenic structures.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号