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At least 631 records · Page 35Linked to original sources
PubMed1986

Recovery of dolichyl diphosphate oligosaccharide in methanolic aqueous phase prepared from rat liver microsomal fractions.

The synthesis of dolichyl diphosphate oligosaccharide was studied by incubating rat liver microsomes (microsomal fractions) with GDP-[14C]mannose, UDP-glucose, UDP-N-acetylglucosamine and [3H]dolichol phosphate. The labelled products obtained by the first step of extraction of the microsomes in methanolic aqueous phase (MAP fraction in chloroform/methanol/water; 3:2:1, by vol.) and in CMW fraction (chloroform/methanol/water; 10:10:3, by vol.) obtained by extraction of the interphase after the first step of extraction were analysed on a DEAE-cellulose column. With the progress of incubation, the radioactivity in unchanged GDP-mannose decreased, whereas the labelled dol-P-P-oligo in the MAP fraction increased about 5-6-fold. The lipid oligosaccharide in this fraction accounted for about 50-60% of the GDP-mannose used, whereas the recovery of the labelled lipid oligosaccharide in the CMW fraction was about 10%. The lipid oligosaccharide from both reactions after mild acid hydrolysis were analysed by gel filtration on Bio-Gel P-4. The oligosaccharide from the MAP fraction gave a peak of higher Mr distinctly separate from the lower-Mr peak obtained from the CMW fraction. Microsomes incubated with labelled lipid oligosaccharide from the MAP fraction showed incorporation of the label into endogenous protein.

Animals↗
PubMed1978

Lipid-bound oligosaccharides in insects.

Membrane preparations from immature stages of the fruit fly Ceratitis capitata catalyze the transfer of mannose from GDP-[14C]mannose into lipid-linked oligosaccharides. These compounds behave as polyprenyl derivatives and their formation is stimulated by the addition of an acidic glycolipid fraction isolated from insects. The mannose-labeled oligosaccharides are attached to the poly-isoprenol by a pyrophosphoryl linkage and can be released by mild acid hydrolysis. The trisaccharide lipid has been partially characterized. The results indicate that the compound is polyprenyl-pyrophosphate-N,N'-diacetylchitobiose-mannose. Incubation of dolichyl phosphate [14C]mannose or lower 14C-labeled oligosaccharide lipids with unlabeled GDP-mannose and the insect enzyme leads to the labeling of a higher lipid-bound oligosaccharide. When UDP-N-acetyl[14C]glucosamine was incubated with insect membranes a 14C-labeled chitobiosyl lipid was synthesized. If unlabeled GDP-mannose was also present, the 14C label appeared in the trisaccharide and higher oligosaccharide lipids. Preliminary evidence indicates that the insect polyprenyl oligosaccharides described here might participate in glycoprotein biosynthesis.

Animals↗
PubMed1965

UTILIZATION OF CELLULOSE OLIGOSACCHARIDES BY CELLVIBRIO GILVUS.

Schafer, Marion L. (Virginia Polytechnic Institute, Blacksburg), and Kendall W. King. Utilization of cellulose oligosaccharides by Cellvibrio gilvus. J. Bacteriol. 89:113-116. 1965.-The hypothesis that oligosaccharides of the cellulose polymer series can be absorbed by cellulolytic bacteria, prior to hydrolysis to the level of glucose or cellobiose, has been tested. Resting-cell suspensions of Cellvibrio gilvus removed oligosaccharides of one to six monomer units from solution at a rate providing the cells with 37 x 10(6) to 42 x 10(6) molecules of glucose per cell per minute. There was no concurrent extracellular hydrolysis of the oligosaccharides. The fact that the rate of uptake was constant indicates that an active absorption system is involved. Filtrates from washed-cell suspensions before or after exposure to the oligosaccharides were incapable of hydrolyzing the sugars. In media where the carbohydrate concentration was growth-limiting, the larger members of the oligosaccharide series supported greater final cell densities than the smaller sugars, but there were no recognizable differences in the growth rates during the logarithmic-growth phase.

Bacteria↗
PubMed1996

Sulphated mucin oligosaccharides from porcine small intestine analysed by four-sector tandem mass spectrometry.

The fraction of sulphated oligosaccharide alditols isolated from mucin glycopeptides of porcine small intestine 'insoluble' mucin complex was analysed by negative-ion fast atom bombardment (FAB) tandem mass spectrometry. Collision-induced dissociation (CID) tandem mass spectra of native and peracetylated species were compared with standards of sulphated monosaccharides. The tandem mass spectra revealed structural information of the carbohydrate sequence and sulphate position. Negative-ion FAB ionization of the peracetylated sulphated oligo-saccharide alditols was at least three times more sensitive than that of the native sulphated oligosaccharide alditols, as revealed by comparing the signal-to-noise ratios, and allowed the detection of eleven compared with six pseudo-molecular ions. Fourteen structures were determined from the CID tandem mass spectra obtained. The main sulphation site was C-6 of an N-acetylglucosamine 6-linked to the N-acetylgalactosaminitol. C-3 of the N-acetylgalactosaminitol could be unsubstituted or extended with a series of up to three monosaccharide residues including blood group H determinants and blood group A determinants. Also, the sulphated N-acetylglucosamine could be further extended. The most abundant structure was a monosulphated trisaccharide with the sequence Gal-->3(SO3-->6GlcNAc-->6)GalNAcol. The sulphation at C-6 of N-acetylglucosamine seems to be a common feature for O-linked oligosaccharides, and has been described both for skeletal keratan sulphates and respiratory mucin oligosaccharides. Low-abundance ions were also detected from oligosaccharides with sulphation at C-3 of an amino sugar residue. This seems to be a novel sulphation site for mucin oligosaccharides.

Acetylation↗
PubMed1999

Matrix optimization for matrix-assisted laser desorption/ionization mass spectrometry of oligosaccharides from human milk.

Neutral and acidic oligosaccharides from human milk were analyzed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI/MS). These experiments require suitable matrices; their selection and particularly their preparation protocols must be optimized. Important criteria are sensitivity, reproducibility, tolerance against impurities and resolution over a wide mass range. For analytical investigations of these oligosaccharides, containing labile fucosylated and sialylated components, another property of a matrix becomes a significant factor, namely the influence on ion stability and the extent of (metastable) fragmentation. The experience gained with the MALDI/MS of neutral and acidic oligosaccharides is summarized taking into account different intentions of measurement and typical problems, such as impurities after enzymatic treatment. For a rapid screening of an oligosaccharide sample, superior results were obtained with a new preparation technique using 5-chloro-2-mercaptobenzothiazole (CMBT) as the first layer for 2,5-dihydroxybenzoic acid. For structural analysis by post-source decay, CMBT as the first layer for 3-aminoquinoline is a favoured preparation protocol, because extensive fragmentation is achieved. For acidic oligosaccharides, a special preparation protocol makes it possible to determine the number of sialic acids by inducing highly effective cationization. Matrix-assisted laser desorption/ionization mass spectrometry; matrices; oligosaccharides; post-source decay.

Gentisates↗
PubMed1999

Post-source decay mass spectrometry: optimized calibration procedure and structural characterization of permethylated oligosaccharides.

Permethylated oligosaccharides were analyzed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI/MS) using a reflectron time-of-flight instrument in the post-source decay (PSD) mode. Under these ionization conditions, such derivatives yield intense signals corresponding to sodium or potassium cationized molecular species. Fragments observed in the PSD spectra result exclusively from cleavage of glycosidic bonds, preferentially at N-acetylhexosamine residues. A systematic study was carried out on a series of permethylated oligosaccharides to allow rationalization of the fragmentation processes. Fragments originating from both the reducing and the non-reducing ends of the oligosaccharide yield information on sequence and branching. Moreover, glycosyl residues linked in position 3 of HexNAc units give rise to a highly specific elimination process, which allows unambiguous assignment of (1-3) interglycosidic linkages. Special attention was paid to the structural analysis of oligosaccharides carrying the commonly encountered fucosyl and sialyl end-caps. In the case of sialylated residues, a targeted methodology involving desialylation and specific CD3-labeling of the nascent free hydroxyl groups was developed to mark the initial location of sialic acid residues along the oligosaccharide backbone. As accurate mass determination of fragment ions is essential for their assignment, a simplified protocol for the calibration in the PSD mode is described. This procedure allows the determination of the correction function parameters required to process the data for an instrument that employs post-acceleration detection. MALDI/PSD-MS of permethylated oligosaccharides, by providing structural information at the low picomole level, appears to be a valuable complement, or an alternative, to the techniques currently in use for carbohydrate structural analysis.

Mass Spectrometry↗
PubMed1991

Non-reducing terminal linkage position determination in intact and permethylated synthetic oligosaccharides having a penultimate amino sugar: fast atom bombardment ionization, collisional-induced dissociation and tandem mass spectrometry.

Certain linkage positions in oligosaccharides can be discerned by collision-activated dissociation mass spectrometry, rationalized by molecular modelling. Previous work on synthetic oligosaccharides has suggested that daughter ion patterns can distinguish among intact compounds which terminate in alpha-L-fucose and have a penultimate amino sugar. The current study indicates that these observations can be extended to oligosaccharides terminating in beta-D-galactose. In addition, we have observed that protonated, ammoniated and lithiated molecular ions all produce linkage-specific daughter ion spectra in these two sets of oligosaccharides. Sodiated molecular ions could be fragmented usefully under high collision energy offset conditions; potassiated ions were stable and not dissociable under conditions available in a triple-quadrupole instrument. We also show linkage discernment among the permethylated set of these six synthetic oligosaccharides. Methylated derivatives of this set of compounds give more useful product ions, including a 3-linkage specific ion. A novel relationship was noted by a plot of collision energy against (daughter ion/parent ion) ratio, which gave a unique slope for each of the non-reducing terminal linkage positions 3, 4 and 6 in the set of six compounds. The slope of this plot is related to the ability of each linkage position in the oligosaccharide to absorb collisional energy. Rotational freedom of the individual glycosidic linkage is hypothesized to play a role in this phenomenon.

Amino Sugars↗
PubMed2005

Combinatorial synthesis of an oligosaccharide library by using beta-bromoglycoside-mediated iterative glycosylation of selenoglycosides: rapid expansion of molecular diversity with simple building blocks.

A new method for constructing an oligosaccharide library composed of structurally defined oligosaccharides is presented based on an iterative glycosylation of selenoglycosides. Treatment of 2-acyl-protected selenoglycosides with bromine selectively generates beta-bromoglycosides, which serve as glycosyl cation equivalents in the oligosaccharide synthesis. Thus, the coupling of the bromoglycosides with another selenoglycoside affords the corresponding glycosylated selenoglycosides, which can be directly used to next glycosylation. The iteration of this sequence allows the synthesis of a variety of oligosaccharides including an elicitor active heptasaccharide. A characteristic feature of the iterative glycosylation is that glycosyl donors and acceptors with the same anomeric reactivity can be selectively coupled by activation of the glycosyl donor prior to coupling with the glycosyl acceptor. Therefore, same selenoglycosides can be used for both the glycosyl donors and the acceptors. This feature has been exemplified by a construction of an oligosaccharide library directed to elicitor-active oligosaccharides. The library composed of stereochemically defined oligoglucosides with considerable structural diversity can be constructed starting from simple selenoglycosides.

Carbohydrate Sequence↗
PubMed1990

Isolation and recovery of acidic oligosaccharides from polyacrylamide gels by semi-dry electrotransfer.

Acidic oligosaccharides derived from glycosaminoglycan heparin were separated by polyacrylamide gradient gel electrophoresis (PAGE). The gel could be visualized using Alcian Blue dye to give a pattern of highly resolved, well defined bands. The particular banding pattern obtained was the result of a heparinase catalyzed depolymerization which afforded oligosaccharide products that differed in size by one disaccharide unit. The separated oligosaccharides could be recovered prior to staining by electroelution onto a positively charged nylon membrane by a semi-dry transfer procedure. Subsequent elution and quantitative recovery of individual oligosaccharides from the membrane was achieved. By using multiple membrane layers a second separation dimension was obtained, resulting in increased oligosaccharide purity proportional to transfer depth. Preparative gradient polyacrylamide gel electrophoresis followed by semi-dry electro-transfer and recovery represents a novel method for the preparation of homogeneous acidic oligosaccharides.

Alcian Blue↗
PubMed1998

Investigation of micelles and anionic cyclodextrins as pseudostationary phases for the capillary electrophoresis separation of oligosaccharides derivatized with 2-amino-benzamide.

Oligomers of glucose and oligosaccharides released from glycoproteins were derivatized with 2-aminobenzamide. As this fluorophore imparts no charge to the oligosaccharides, several strategies were investigated to achieve capillary electrophoresis (CE) separation of both neutral and charged derivatized glycans. Micellar electrokinetic capillary chromatography (MEKC) with the addition of anionic surfactants was evaluated as a first approach: sodium dodecyl sulfate (SDS) produced the best separation of the oligoglucose fragments, where the migration was inversely related to their degree of polymerization. To demonstrate the applicability of this method for complex carbohydrate analysis, oligosaccharide mixtures derived from ribonuclease B (RNase B) and alpha-acid glycoprotein (alpha-AGP) were analyzed. A satisfactory separation for the high-mannose structures found in RNase B could be obtained, whereas charged oligosaccharides from alpha-AGP were poorly resolved. Cyclodextrin-modified CE was chosen as the second approach: the effect of the addition of sulfobutylether-beta-cyclodextrin (SBE-beta-CD) or sulfobutylether-gamma-cyclodextrin (SBE-gamma-CD) on the electrophoretic mobilities and resolution of neutral and charged oligosaccharides was then studied. Selectivity of sialylated structures could be further improved by using anionic cyclodextrins (CDs) instead of micelles. However, this latter approach failed to baseline-resolve the different high-mannose structures of RNase B. A successful separation of the complex mixture of oligosaccharides from alphaalpha-AGP was obtained with the addition of 4% of SBE-gamma-CD and triethylamine (TEA) in a phosphate buffer, pH 6.7.

Anions↗
PubMed1998

Profiling glycoprotein n-linked oligosaccharide by capillary electrophoresis.

A method for analysis of N-linked oligosaccharides derived from glycoproteins including sialic acid-containing species is presented. It is based on the combination of specific chemical and enzymatic conversions coupled with capillary electrophoretic (CE) separation and laser-induced fluorescence (LIF) detection. Glycoproteins were heat-denatured in the presence of a reducing agent and the N-linked oligosaccharides were released by peptide N-glycosidase (PNGase F; EC3.5.1.52)-catalyzed hydrolysis. The released N-linked oligosaccharides were derivatized with 8-aminopyrene-1,3,6-trisulfonate (APTS) under mild reductive amination conditions in which desialylation and loss of fucose residues are minimized. A model N-linked oligosaccharide, desialylated, galactosylated biantennary, core-substituted with fucose (A2F) was tested for APTS-based derivatization chemistry with excellent recovery of the adduct without losing fucose and neuraminic acid residues. The profiles of heavily sialylated N-linked oligosaccharides derived from fetuin, recombinant human erythropoietin and kallikrein are reported and the data show that the present method produces a high resolution of the N-linked oligosaccharide profile for fingerprinting glycans derived from glycoproteins.

Amidohydrolases↗
PubMed2003

Ultrafast analysis of oligosaccharides on microchip with light-emitting diode confocal fluorescence detection.

We have developed a new method for the high-speed separation and high-sensitivity detection of complex oligosaccharides based on microchip electrophoresis (nu-CE) with light-emitting diode (LED) confocal fluorescence detection. Oligosaccharides labeled with 8-aminopyrene-1,3,6-trisulfonate (APTS) were found to strongly adsorb to the surface of polymethylmethacrylate (PMMA) microchips. Accordingly, three classes of major dynamic coating additives were systematically investigated, and cellulose derivatives were found to specifically suppress such adsorption and allow high-performance separation on PMMA chips. Additive concentration, buffer pH and applied field strength were found to be key factors in the high-performance separation& of APTS-labeled oligosaccharides on PMMA chips. Under optimal conditions, 15 oligosaccharides in dextrin hydrolysate can be separated within 45 s with an electrophoretic separation efficiency of over 400 000 theoretical plates per meter. The relative standard deviation (RSD) values of migration times of fourteen oligosaccharides were less than 0.50% between six different channels, and the detection limit for APTS-labeled glucose was about 1.98 x 10(-8) mol/L or 8.61 amol with a signal-to-noise ratio (S/N) of 3. The high speed, high efficiency and high sensitivity of this micro-CE-based method indicate that it can be widely applied to analysis of complex oligosaccharides.

Electrophoresis, Capillary↗
PubMed1989

Different class I antigen oligosaccharides on a murine tumor and a lectin-resistant variant are not responsible for the differential recognition of the tumors by CTL.

Previous studies have shown that whereas a highly malignant mouse cell line termed MDAY-D2 (d haplotype) does not elicit a detectable response by cytotoxic T lymphocytes (CTL) in DBA/2 mice, strong anti-tumor CTL are generated against a wheat-germ-agglutinin-resistant variant, designated MDW3. Additional evidence suggests these anti-MDW3 CTL may not be a consequence of a unique antigenic determinant on the variant cells. Because MDW3 cells are expected to differ from MDAY-D2 cells in their surface carbohydrate structures (due to their lectin resistance) and Class I major histocompatibility molecules play a crucial role in CTL-mediated responses, we speculated that the Asn-linked oligosaccharides present on Class I molecules of MDAY-D2 and MDW3 might be different and could potentially influence recognition analyses and Con A-Sepharose affinity chromatography clearly demonstrated that the oligosaccharides isolated from the H-2Dd molecule of MDAY-D2 cells are larger and more highly branched than those of the MDW3 variant. Taken together with the finding that anti-MDW3 CTL are restricted by H-2Dd, these results suggested that the larger H-2Dd oligosaccharides on MDAY-D2 cells could potentially mask or perturb determinants required for recognition by these CTL. To test this postulate, the surface Class I oligosaccharides of both MDAY-D2 and MDW3 cells were converted to simpler hybrid structures by treatment with the oligosaccharide processing inhibitor, swainsonine. However, no effect was observed on the lysis or binding of either MDAY-D2 or MDW3 cells by anti-MDW3 CTL. Thus, the results do not support the possibility that the larger H-2Dd oligosaccharides on MDAY-D2 cells are, in themselves, responsible for the poor recognition of the parent tumor by anti-MDW3 CTL. Our data do indicate, however, that CTL target binding and effector functions are not dependent on the fine structure of complex Asn-linked carbohydrates present on Class I molecules and possibly on other, accessory molecules at the target cell surface, since MDW3 cells maintained their sensitivity to lysis by CTL following swainsonine treatment.

Alkaloids↗
PubMed1989

Evidence that beta 1-6 branched Asn-linked oligosaccharides on metastatic tumor cells facilitate invasion of basement membranes.

In previous studies we have shown that the ability of murine tumor cells to metastasize in situ is directly linked to expression of -GlcNAc beta 1-6Man alpha 1-6Man beta 1-branched complex-type Asn-linked oligosaccharides in tumor-cell glycoproteins. Here we demonstrate that cell-surface expression of beta 1-6 branched oligosaccharides in metastatic tumor cells is specifically associated with increased invasion of human amnion basement membranes in vitro. Compared to nonmetastatic SP1 murine mammary carcinoma cells, 2 metastatic sublines expressed higher levels of beta 1-6 branched oligosaccharides and were found to be invasive but poorly adhesive on the amnion basement membrane. Swainsonine, a non-toxic inhibitor of Asn-linked oligosaccharide processing which blocks the pathway prior to initiation of the beta 1-6 linked antenna, blocked metastatic tumor-cell invasion and increased adhesiveness. Swainsonine and the metalloprotease inhibitor O-phenanthroline inhibited invasion, apparently via independent mechanisms. O-phenanthroline did not affect tumor-cell adhesion to the amnion basement membrane and swainsonine did not block secretion of metalloproteases, beta-hexosaminadase or tissue plasminogen activator activity by the tumor cells. These results suggest that tumor-cell invasion of basement membranes requires both secretion of hydrolase activities and expression of beta 1-6 branched complex-type oligosaccharides at the tumor cell surface, such oligosaccharides being associated with reduced tumor-cell adhesion to extracellular matrix.

Alkaloids↗
PubMed1988

Dolichol-linked oligosaccharide and glycoprotein biosyntheses in glial cells in primary culture: development and enzymatic correlates.

Primary cultures of cerebral glia derived from neonatal rat brain were utilized to determine 1) the developmental changes of dolichol-linked oligosaccharide and N-linked glycoprotein biosyntheses, 2) the enzymatic correlates of these developmental changes, and 3) the temporal relations between the biosyntheses of dolichol-oligosaccharide and N-linked glycoproteins and the biochemical expression of astrocytic and oligodendroglial differentiation. Marked, parallel developmental increases in the rates of incorporation of [3H]glucosamine into both dolichol-oligosaccharide and glycoprotein were observed, with maximal rates achieved after 9-10 days in culture and little change occurring over the next 10 days in culture. Concerning the enzymatic correlates, dolichol kinase exhibited a moderate developmental increase with a maximum at 5 days in culture, whereas the activities of the three critical enzymes that utilize dolichyl phosphate in the synthesis of the dolichol-linked oligosaccharide, i.e., N-acetylglucosaminylphosphotransferase (GlcNAc-1-P transferase), mannosylphosphoryldolichol (Man-P-Dol) synthase, and glucosylphosphoryldolichol (Glc-P-Dol) synthase, reached maxima after 6-9 days in culture. Both the activity of Man-P-Dol synthase in vitro and the rate of formation of its product, Man-P-Dol, in intact cells were shown to correlate closely with the rates of oligosaccharide and glycoprotein biosyntheses. An important regulatory role for Man-P-Dol synthase and its product, Man-P-Dol, was suggested further by the demonstration of a maturation-dependent activation by Man-P-Dol of GlcNAc-1-P transferase, the first committed step in the pathway. Two enzymatic markers of astrocytic (glutamine synthetase) and oligodendroglial (2',3'-cyclic nucleotide 3'-phosphohydrolase) differentiation exhibited marked developmental increases in activity with onset at the time of attainment of peak rates of dolichol-oligosaccharide and glycoprotein biosyntheses. Importance of the latter processes for glial differentiation is suggested.

Animals↗
PubMedDate not supplied

Size distribution and general structural features of N-linked oligosaccharides from the methylotrophic yeast, Pichia pastoris.

The secreted glycoproteins of Pichia pastoris contain more than 35% of their N-linked oligosaccharides as structures smaller than Man14GlcNAc2 (Man = mannose; GlcNAc = N-acetylglucosamine). On heterologous invertase produced in P. pastoris, approximately 85% of the oligosaccharides are in the size range Man8-14GlcNAc2. The structures appear to contain alpha-linked mannose. In addition, one-third of the structures contain net negative charge and can be radio-labelled in vivo with 32P. The largest oligosaccharides isolated from P. pastoris are significantly shorter than the hypermannosylated structures typical of S. cerevisiae, indicating that the factors which influence the processing of N-linked oligosaccharides in P. pastoris are different from those which influence processing in S. cerevisiae. The smaller N-linked oligosaccharides synthesized by P. pastoris resemble high-mannose oligosaccharides synthesized by animal cells, and this finding increases the utility of P. pastoris as a host for the production of heterologous glycoproteins.

Cell Fractionation↗
PubMed2002

Characterization of N-linked oligosaccharides attached to recombinant human antithrombin expressed in the yeast Pichia pastoris.

We studied the structures of four N-linked oligosaccharide chains of the recombinant human antithrombin (rAT) expressed in the yeast Pichia pastoris. rAT was fully glycosylated at Asn 96 and Asn 155, whereas the glycosylation on Asn 135 and Asn 192 was partial. The glycosylation level on Asn 135 was only 12% and this reduction is assumed to be one of the reasons for a higher heparin-binding affinity of rAT than plasma-derived human antithrombin (pAT). In order to determine the sizes and electrostatic charges of the N-linked oligosaccharides, rAT was treated with PNGase F, and the reduced ends were labelled by pyridylamination followed by analysis using anion exchange and amide adsorption columns. The N-linked oligosaccharides were 78% neutral and 22% phosphomannosylated. The neutral oligosaccharides were thought to be Man(9-12)GlcNAc(2) as their major components. The phosphomannosylated oligosaccharides were then subjected to mild acid hydrolysis and/or digestion with alkaline phosphatase, and their charge shifts were analysed by the affinity to an anion exchange column. Among phosphomannosylated oligosaccharides, monophosphate diester type was predominant, whereas negatively charged diphosphate diester and monophosphate monoester types were minor components. The mannose residues at the non-reducing end(s) of Man(9-12)GlcNAc(2) were phosphomannosylated or phosphorylated and these are the major components. Because rAT is less negatively charged than pAT, which has disialyl biantennary N-glycans, it might be less repulsive to pentasaccharide-bearing anticoagulantly active heparan sulphate proteoglycan molecules exposed on the surface of the damaged vascular vessels.

Alkaline Phosphatase↗
PubMed1994

Developmentally regulated oligosaccharides in mouse spermatogenic cells.

Mouse spermatogenic cells were separated into four populations, pachytene spermatocytes, round spermatids, elongated spermatids, and residual bodies. Each cell population was metabolically labeled with [3H]galactose, [3H]glucosamine, or [3H]fucose. Glycopeptides were prepared from the radiolabeled glycoproteins by pronase digestion and fractionated by serial lectin affinity chromatography and gel filtration. The presence of O-linked oligosaccharides was assessed by pronase digestion of [3H]galactose-labeled glycoproteins, exclusion of the radiolabeled glycopeptides from a ConA-Sepharose column, gel filtration, and treatment with alkaline borohydride. This analysis reveals that a large proportion of [3H]galactose-labeled oligosaccharides (47-52%) are O-linked structures, while the majority (80-90%) of [3H]fucose-labeled oligosaccharides are N-linked. The proportions of triantennary, biantennary, oligomannose, and hybrid oligosaccharides linked to asparagine vary with the cell populations. Furthermore, in round spermatids, but not in the other cell populations, a relatively large proportion (15%) of [3H]glucosamine-labeled oligosaccharides consists of terminal O-linked N-acetylglucosamine. Taken together these data show that each spermatogenic cell population contains a unique complement of oligosaccharide structures that could play an important role as differentiation signals in the interactions among these cells and/or with Sertoli cells.

Animals↗