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PubMed2004

Synthesis of the trisaccharide repeating unit of the atypical O-antigen polysaccharide from Danish Helicobacter pylori strains employing the 2'-carboxybenzyl glycoside.

[reaction: see text] Synthesis of the unique trisaccharide repeating unit of the O-polysaccharide of the lipopolysaccharide from Danish Helicobacter pylori strains has been accomplished. Key steps include the coupling of three monosaccharide moieties by glycosylations employing the 2'-carboxybenzyl glycoside method. Also presented is a method for the synthesis of the novel branched sugar, 3-C-methyl-D-mannose, which is one of three monosaccharide components.

Carbohydrate Conformation↗
PubMed1998

Effect of shape, size, and valency of multivalent mannosides on their binding properties to phytohemagglutinins.

Clusters of di-, tri-, and tetra-antennary alpha-D-mannopyranosides were synthesized in good yields based on the coupling of amine-bearing mono- or trisaccharide [Man alpha(1 --> 6)[Man alpha(1 --> 3)]Man] haptens to poly-isocyanate or -isothiocyanate tethering cores. The relative binding properties of the resulting multivalent ligands were determined by turbidimetric and solid phase enzyme-linked lectin assays (ELLA) using plant lectins (phytohemagglutinins) Concanavalin A (Con A) and Pisum sativum (pea lectin) having four and two carbohydrate binding sites, respectively. Rapid and efficient cross-linking between tetravalent Con A and mannopyranosylated clusters were measured by a microtiter plate version of turbidimetric analyses. In inhibition of binding of the lectins to yeast mannan, the best tetravalent monosaccharide (30) and trisaccharide (31) inhibitors were shown to be 140 and 1155 times more potent inhibitors than monomeric methyl alpha-D-mannopyranoside against pea lectin and Con A, respectively. Compounds 30 and 31 were thus 35- and 289-fold more potent than the reference monosaccharide based on their hapten contents. As a general observation, the ligands bearing the Man alpha(1 --> 6)[Man alpha(1 --> 3)]Man trimannoside structures were found to be more potent inhibitors for Con A than the ligands having single mannoside residues, whereas pea lectin could not discriminate between the two types of ligands.

Binding Sites↗
PubMed1990

Antiendotoxin activity of lipid A analogues: requirements of the chemical structure.

Lipid X, a monosaccharide precursor of lipid A, has been found to prevent death in animals given a lethal dose of endotoxin, but the mechanism of this protective effect is unknown. We previously reported that lipid X blocks endotoxin-induced priming of human neutrophils in a manner consistent with competitive inhibition. To determine the molecular requirements for this antiendotoxin activity, we studied several derivatives of lipid X using the neutrophil priming assay. Neutrophil priming was quantitated by measuring stimulated superoxide (O2-) release. The removal of either acyl group from lipid X or even the simple change of the amide to an ester linkage at C2 of the glucosamide ring resulted in a marked loss of antagonism. Monosaccharide analogues, structurally related to native lipid A by the presence of acyloxyacyl side chains, demonstrated marked inhibition of endotoxin-induced priming at low concentrations but an endotoxin-like, priming effect at high concentrations. The addition of a phosphate group at position 4 of the sugar moiety was the only modification studied so far that produced a pure antagonist with increased antiendotoxin activity. Demonstration of these structural requirements for the antiendotoxin activity of lipid A analogues supports the hypothesis that this effect may be mediated via specific cellular binding sites. Lipid X derivatives may be useful for studying the interaction of endotoxin with cells and their antiendotoxin activity may prove beneficial in the treatment of septicemia.

Bacterial Infections↗
PubMed1998

Isolation and characterization of two forms of an acidic bromelain stem proteinase.

Two forms of an acidic bromelain proteinase isolated from crude bromelain, an extract from pineapple stem, were found by a two-step FPLC purification procedure. The basic main components were removed by cation exchange chromatography and the breakthrough fraction was further resolved by anion exchange chromatography into 15 protein fractions, only two of which, called SBA/a and SBA/b, were proteolytically active. These components were characterized by electrospray mass spectroscopy (ESMS), isoelectric focusing, N-terminal amino acid sequence analysis, monosaccharide analysis, and enzymatic parameters. The molecular masses of SBA/a and SBA/b were determined by ESMS to be 23,550 and 23,560, respectively. The isoelectric points (pI) of the two bands of SBA/a were 4.8 and 4.9; SBA/b focused as a single band at pI = 4.8. Partial N-terminal amino acid sequences (11 residues) were identical to SBA/a and SBA/b and identical with those of stem bromelain, the basic main proteinase of the pineapple stem, and fruit bromelain, the acidic main proteinase of the pineapple fruit. Both components are highly glycosylated; hydrolysis of SBA/a yielded about twofold more monosaccharide per protein than SBA/b. The comparison of the catalytic properties of SBA/a with those of SBA/b revealed no relevant differences in the hydrolysis of three peptidyl-NH-Mec substrates and in the inhibition profiles using chicken cystatin and E-64, indicating that these components can be considered as two forms of a single enzyme. Both forms are scarcely inhibited by chicken cystatin and slowly inactivated by E-64, hence are nontypical cysteine proteinases of the papain superfamily.

Amino Acid Sequence↗
PubMedDate not supplied

[Polar components of Black sea seaweed Colpomenia peregrina (Sauv.) Hamel].

GC-MS of trimethylsilyl derivatives of the compounds present in the butanolic extract of biomass of brown seaweed Colpomenia peregrina from the Black Sea aided in identification of 24 components, including aliphatic hydroxy and keto and aromatic acids, glycerol, mannitol, floridoside, and monosaccharides. The polysaccharide composition of the biomass was also studied, with high sodium alginate and laminaran contents and a comparatively low level of fucoidan being revealed. The polysaccharides were isolated from the biomass by fractional extraction and purified by precipitation or ion exchange chromatography. The structures of alginic acid and laminaran were deduced from 13C NMR spectra and confirmed, in the case of laminaran, by methylation analysis. The sodium alginate was shown to contain more guluronic (G) than mannuronic acid (M) residues, the M/G ratio being 0.48. Laminaran was demonstrated to be a beta-glucan with 1-->3 linkages in its backbone and 1-->6 linkages in its branching points, which is characteristic of brown algae. Fucoidan turned out to be a complex heteropolysaccharide containing, in addition to fucose and sulfate, other neutral monosaccharides and uronic acids. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2004, vol. 30, no. 2; see also http://www.maik.ru

Chromatography, Ion Exchange↗
PubMed2000

Lectin purified human class I MHC-derived peptides: evidence for presentation of glycopeptides in vivo.

Previously, using synthetic glycopeptides carrying a natural cytosolic type of monosaccharide O-beta-linked N-acetylglucosamine (GlcNAc) glycosylation of serine residues, we have shown that glycopeptides act as suitable substrates for TAP-mediated transport into the endoplasmic reticulum (ER), and that they bind efficiently to class I major histocompatibility complex (MHC) molecules and can elicit glycopeptide-specific cytotoxic T-lymphocyte (CTL) responses in mice. Recently, we have reported that peptides presented by human class I MHC molecules in vivo encompass a small but significant amount of peptides which seem to be carrying O-beta-linked monosaccharide GlcNAc. In the present report we provide further evidence that glycosylated peptides are indeed presented by class I MHC molecules in vivo. Thus, peptides derived from HLA-A*0201 were purified by wheat germ agglutinin (WGA) lectin affinity chromatography as previously described. Subsequently, the peptides contained in the WGA-eluate were subjected to sequence analysis by Edman degradation. It was found that the peptides derived from HLA-A*0201 which had been retained by the O-GlcNAc-binding lectin WGA did indeed carry a HLA-A*0201 binding motif. Furthermore, using an enzymatic labeling procedure we present evidence that the HLA-A*0201-derived peptides which bind to the WGA lectin are glycosylated with terminal GlcNAc residues. Together, these data provide further evidence for the natural presentation by human class I MHC of glycopeptides carrying terminal O-GlcNAc residues in vivo.

Acetylglucosamine↗
PubMed2006

Characterization of a carbohydrate transporter from symbiotic glomeromycotan fungi.

The symbiotic relationships between mycorrhizal fungi and plants have an enormous impact on terrestrial ecosystems. Most common are the arbuscular mycorrhizas, formed by fungi belonging to the phylum Glomeromycota. Arbuscular mycorrhizal fungi facilitate the uptake of soil nutrients by plants and in exchange obtain carbohydrates, thus representing a large sink for atmospheric plant-fixed CO(2). However, how carbohydrates are transported through the symbiotic interface is still unknown. Here we report the characterization of the first known glomeromycotan monosaccharide transporter, GpMST1, by exploiting the unique symbiosis of a glomeromycotan fungus (Geosiphon pyriformis) with cyanobacteria. The GpMST1 gene has a very low GC content and contains six introns with unusual boundaries. GpMST1 possesses twelve predicted transmembrane domains and functions as a proton co-transporter with highest affinity for glucose, then mannose, galactose and fructose. It belongs to an as yet uncharacterized phylogenetic monosaccharide transporter clade. This initial characterization of a new transporter family involved in fungal symbiosis will lead to a better understanding of carbon flows in terrestrial environments.

Biological Transport↗
PubMed2004

Determination of the mode and efficacy of the cross-linking of guar by borate using MAS 11B NMR of borate cross-linked guar in combination with solution 11B NMR of model systems.

The reaction product of boric acid and the polysaccharide guaran (the major component of guar gum) has been investigated by 11B NMR spectroscopy. By comparison with the 11B NMR of boric acid and phenylboronic acid complexes of 1,2-diols (HOCMe2CMe2OH, cis-C6H10(OH)2, trans-C6H10(OH)2, o-C6H4(OH)2), 1,3-diols (neol-H2), monosaccharides (L-fucose, mannose and galactose) and disaccharides (cellobiose and sucrose) it is found that the guaran polymer is cross-linked via a borate complex of two 1,2-diols both forming chelate 5-membered ring cycles ([B5(2)]), this contrasts with previous proposals. Based upon steric constraints we propose that preferential cross-linking the guaran polymer occurs via the 3,4-diols of the galactose side chain. The DeltaH and DeltaS for complexation of boric acid to cis- and trans-1,2-cyclohexanediol have been determined, from the temperature dependence of the appropriate equilibrium constants, and used in conjunction with ab initio calculations on model compounds, to understand prior conflicting proposals for guaran-boric acid interactions. 11B NMR derived pH dependent equilibrium constants and ab initio calculations have been used to understand the reasons for the inefficiency of boric acid to cross-link guaran (almost 2 borate ions per 3 monosaccharide repeat units are required for a viscous gel suitable as a fracturing fluid): the most reactive sites on the component saccharides (mannose and galactose) are precluded from reaction by the nature of the guar structure; the comparable acidity (pKa) of the remaining guaran alcohol substituents and the water solvent, results in a competition between cross-linking and borate formation; a significant fraction of the boric acid is ineffective in cross-linking guar due to the modest equilibrium (Keq). In contrast to prior work, we present evidence for the reaction of alcohols with boric acid, rather than the borate anion. Based upon the results obtained for phenylboronic acid, alternative cross-linking agents are proposed.

Boric Acids↗
PubMed2005

Computational studies of 13C NMR chemical shifts of saccharides.

The (13)C NMR chemical shifts for alpha-D-lyxofuranose, alpha-D-lyxopyranose (1)C(4), alpha-D-lyxopyranose (4)C(1), alpha-D-glucopyranose (4)C(1), and alpha-D-glucofuranose have been studied at ab initio and density-functional theory levels using TZVP quality basis set. The methods were tested by calculating the nuclear magnetic shieldings for tetramethylsilane (TMS) at different levels of theory using large basis sets. Test calculations on the monosaccharides showed B3LYP(TZVP) and BP86(TZVP) to be cost-efficient levels of theory for calculation of NMR chemical shifts of carbohydrates. The accuracy of the molecular structures and chemical shifts calculated at the B3LYP(TZVP) level is comparable to those obtained at the MP2(TZVP) level. Solvent effects were considered by surrounding the saccharides by water molecules and also by employing a continuum solvent model. None of the applied methods to consider solvent effects was successful. The B3LYP(TZVP) and MP2(TZVP)(13)C NMR chemical shift calculations yielded without solvent and rovibrational corrections an average deviation of 5.4 ppm and 5.0 ppm between calculated and measured shifts. A closer agreement between calculated and measured chemical shifts can be obtained by using a reference compound that is structurally reminiscent of saccharides such as neat methanol. An accurate shielding reference for carbohydrates can be constructed by adding an empirical constant shift to the calculated chemical shifts, deduced from comparisons of B3LYP(TZVP) or BP86(TZVP) and measured chemical shifts of monosaccharides. The systematic deviation of about 3 ppm for O(1)H chemical shifts can be designed to hydrogen bonding, whereas solvent effects on the (1)H NMR chemical shifts of C(1)H were found to be small. At the B3LYP(TZVP) level, the barrier for the torsional motion of the hydroxyl group at C(6) in alpha-D-glucofuranose was calculated to 7.5 kcal mol(-1). The torsional displacement was found to introduce large changes of up to 10 ppm to the (13)C NMR chemical shifts yielding uncertainties of about +/-2 ppm in the chemical shifts.

Carbon Isotopes↗
PubMed2001

Determination of the chemical structure of the capsular polysaccharide of strain B33, a fast-growing soya bean-nodulating bacterium isolated from an arid region of China.

We have determined the structure of a polysaccharide from strain B33, a fast-growing bacterium that forms nitrogen-fixing nodules with Asiatic and American soya bean cultivars. On the basis of monosaccharide analysis, methylation analysis, one-dimensional 1H- and 13C-NMR and two-dimensional NMR experiments, the structure was shown to consist of a polymer having the repeating unit -->6)-4-O-methyl-alpha-D-Glcp-(1-->4)-3-O-methyl-beta-D-GlcpA-(1--> (where GlcpA is glucopyranuronic acid and Glcp is glucopyranose). Strain B33 produces a K-antigen polysaccharide repeating unit that does not have the structural motif sugar-Kdx [where Kdx is 3-deoxy-D-manno-2-octulosonic acid (Kdo) or a Kdo-related acid] proposed for different Sinorhizobium fredii strains, all of them being effective with Asiatic soya bean cultivars but unable to form nitrogen-fixing nodules with American soya bean cultivars. Instead, it resembles the K-antigen of S. fredii strain HH303 (rhamnose, galacturonic acid)n, which is also effective with both groups of soya bean cultivars. Only the capsular polysaccharide from strains B33 and HH303 have monosaccharide components that are also present in the surface polysaccharide of Bradyrhizobium elkanii strains, which consists of a 4-O-methyl-D-glucurono-L-rhamnan.

Carbohydrate Conformation↗
PubMed2002

Structure determination of the exopolysaccharide produced by Lactobacillus rhamnosus strains RW-9595M and R.

Exopolysaccharides (EPSs) were isolated and purified from Lactobacillus rhamnosus strains RW-9595M, which has been shown to possess cytokine-stimulating activity, and R grown under various fermentation conditions (carbon source, incubation temperature and duration). Identical (1)H NMR spectra were obtained in all cases. Molecular masses were determined by gel permeation chromatography. The primary structure was elucidated using chemical and spectroscopic techniques. Organic acid, monosaccharide and absolute configuration analyses gave the following composition: pyruvate, 1; D-glucose, 2; D-galactose, 1; and l-rhamnose, 4. Methylation analysis indicated the presence of three residues of 3-linked rhamnose, and one residue each of 2,3-linked rhamnose, 2-linked glucose, 3-linked glucose and 4,6-linked galactose. The EPS was submitted to periodate oxidation followed by borohydride reduction. Monosaccharide analysis of the resulting polysaccharide gave the new composition: rhamnose, 4; and glucose, 1. Methylation analysis confirmed the loss of the 2-linked glucose and 4,6-linked galactose residues. On the basis of one- and two-dimensional (1)H and (13)C NMR data, the structure of the native EPS was consistent with the following heptasaccharide repeating unit: [3Rha alpha-3Glc beta-3[Gal4,6(R)Py alpha-2]Rha alpha-3Rha alpha-3Rha alpha-2Glc alpha-](n) where Rha corresponds to rhamnose (6-deoxymannose) and Py corresponds to pyruvate acetal. Complete (1)H and (13)C assignments are reported for the native and the corresponding pyruvate-hydrolysed polysaccharide. Electrospray MS and MS/MS data are given for the oligosaccharide produced by Smith degradation.

Carbohydrate Sequence↗
PubMed2005

Hydrolysis characteristics of a beta-1,3-D-glucan elicitor from yeast.

Fluorophore-assisted carbohydrate electrophoresis (FACE) is a straightforward, sensitive method for determining the presence and relative abundance of individual (oligo)saccharides in a(n) (oligo)saccharide mixture. The single-terminal aldehydes of oligoglucoside residues released by acid hydrolysis of beta-1,3-D-glucan from yeast were tagged with the charged fluorophore ANTS (8-aminonaphthalene-1,3,6-trisulphonate), and separated with high resolution on the basis of size by PAGE. ANTS fluorescence labelling was not biased by oligoglucoside length; therefore band fluorescence intensity was directly related to the relative abundance of individual oligoglucoside moieties in a heterogeneous sample. FACE analysis revealed that the major oligoglucoside mixture released by acid hydrolysis from beta-1,3-D-glucan was composed of monosaccharide, disaccharide, trisaccharide, tetrasaccharide, pentasaccharide, hexasaccharide, heptasaccharide and octasaccharide, and the order of abundance from high to low was trisaccharide, monosaccharide, disaccharide, tetrasaccharide, pentasaccharide, hexasaccharide, heptasaccharide and octasaccharide respectively. In conclusion, FACE represents an accessible, sensitive and quantitative analytical tool enabling the characterization of a(n) (oligo)saccharide mixture.

Carbohydrate Sequence↗
PubMed1970

Biosynthesis of glycosaminoglycans in bovine cornea. The effet of uridine diphosphate xylose.

1. The role of UDP-xylose in the regulation of corneal glycosaminoglycan biosynthesis was investigated. Bovine corneas were incubated with [U-(14)C]-glucose in the presence and in the absence of the nucleotide, and the radioactivity of chondroitin, chondroitin sulphate and keratan sulphate, as well as of their monosaccharide constituents, was determined. 2. A decrease in the rate of biosynthesis of chondroitin and chondroitin sulphate and an increase in that of keratan sulphate were observed in the samples incubated with UDP-xylose. 3. The UDP-glucuronic acid isolated after the incubation in the presence of UDP-xylose showed a noticeable decrease in the amount of radioactivity incorporated; this result suggests that UDP-xylose inhibits the UDP-glucose dehydrogenase, causing an accumulation of UDP-glucose and consequently an increase in the formation of UDP-galactose and keratan sulphate. 4. Galactose and galactosamine isolated from the polysaccharides showed variations in the amount of radioactivity incorporated in accordance with those observed for the macromolecules; this fact confirms that in the system we used in vitro a real biosynthesis of the polysaccharide chain took place and that the regulatory effect of UDP-xylose was active at the monosaccharide level.

Alcohol Oxidoreductases↗
PubMed1973

The purification, composition and specificity of wheat-germ agglutinin.

1. The purification of wheat-germ agglutinin from commercial wheat germ is described. By ion-exchange chromatography three active proteins (isolectins) were separated, one of which was examined in detail. 2. The amino acid composition is unusual, as 20% of residues are half-cystine and 21% are glycine. Unlike most lectins and contrary to previous reports, this protein is not a glycoprotein. 3. The efficiency of various saccharides as inhibitors of the agglutination reaction was investigated and from this the specificity of the binding site was inferred. Of monosaccharides, only derivatives of glucose with a 2-acetamido group and a free 3-hydroxyl group are effective inhibitors, and glycosides of either anomeric configuration are bound. Oligosaccharides are much more powerful inhibitors of agglutination than are monosaccharides. 4. It is proposed that the binding site consists of three or four subsites with differing specificities, in a cleft in the molecule resembling that proposed for hen's-egg-white lysozyme.

Amino Acids↗
PubMed1974

Distribution of sulphate and iduronic acid residues in heparin and heparan sulphate.

1. A method was developed for determination of the uronic acid composition of heparin-like glycosaminoglycans. Polymers or oligosaccharides are degraded to monosaccharides by a combination of acid hydrolysis and deamination with HNO(2). The resulting uronic acid monosaccharides (accounting for about 70% of the uronic acid contents of the starting materials) are isolated and converted into the corresponding aldono-1,4-lactones, which are separated by g.l.c. The calculated ratios of glucuronic acid/iduronic acid are reproducible within 5%. 2. Samples of heparin from pig intestinal mucosa (molar ratio of sulphate/disaccharide unit, 2.40) and heparan sulphate from human aorta (sulphate/disaccharide ratio, 0.46) were subjected to uronic acid analysis. l-Iduronic acid constituted 77% and 19% respectively of the total uronic acid contents. 3. The correlation between the contents of sulphate and iduronic acid indicated by this finding also applied to the fractionated deamination products of the two polymers. The sulphated fragments varied in size from disaccharide to octasaccharide (or larger) and showed sulphate/disaccharide molar ratios in the range of 0.05-2.0. The proportion of iduronic acid increased with increasing ester sulphate contents of the oligosaccharides. 4. Previous studies on the biosynthesis of heparin in a cell-free system have shown that l-iduronic acid residues are formed by C-5 epimerization of d-glucuronic acid units at the polymer level; the process requires concomitant sulphation of the polymer. The results obtained in the present structural study conform to these findings, and suggest further that similar mechanisms may operate in the biosynthesis of heparan sulphate. The epimerization reaction appears to be linked to the sulphation of hydroxyl groups but does not seem to require sulphation of the target uronic acid residues. The significance of sulphamino groups in relation to the formation of iduronic acid is unknown.

Animals↗
PubMed1975

Characterization by gas-liquid chromatography-mass spectrometry and proton-magnetic-resonance spectroscopy of pertrimethylsilyl methyl glycosides obtained in the methanolysis of glycoproteins and glycopeptides.

The quantitative analysis by gas chromatography of monosaccharides present in glycoproteins and glycopeptides using methanolysis, followed by re-N-acetylation and trimethylsilylation, gives rise to several peaks for each monosaccharide. The identity of these peaks for xylose, fucose, mannose, galactose, glucose, N-acetylglucosamine, N-acetylgalactosamine and N-acetylneuraminic acid was established for alpha- and beta-methyl pyranosides and furanosides by combined g.l.c.-mass spectrometry and proton-magnetic-resonance spectroscopy. These data provide for the unambiguous interpretation of the gas chromatograms obtained in the application of this g.l.c. method, and supply basic information for the further application of mass spectrometry in this field.

Chromatography, Gas↗
PubMed1979

Hydroxylysine-linked glycosides of human complement subcomponent C1q and various collagens.

1. Human C1q, a subcomponent of the first component of complement, contains 67 disaccharides (glucosylgalactose) and 2.4 monosaccharides (galactose) linked to hydroxylysine in one molecule. It was found that 82.6% of the hydroxylsine residues were glycosylated. The suggestion of the possible existence of glucosylgalactosylhydroxylysine reported previously [Yonemasu, Stroud, Niedermeir & Butler (1971) Biochem. Biophys. Res. Commun. 43, 1388--1394] was confirmed. 2. The hydroxylysine-glycosides are not detected in the C-terminal, non-collagen-like, globular regions, but only in the collagen-like regions in the subcomponent C1q molecule. 3. Alpha 1(I) and alpha 2 in pig skin, alpha 1(II) in bovine cartilage and alpha 1(III) in bovine skin collagens contain 2.0, 2.2, 13.2 and 2.0 residues of hydroxylysine-glycosides per molecule, respectively. The percentage of hydroxylysine residues glycosylated in each of these chains is relatively low (on average 38%). 4. Neither the high percentage of hydroxylysine residues glycosylated nor the high values for the ratios of disaccharides to monosaccharides in the subcomponent C1q resembles that in alpha 1(I), alpha 2, alpha 1(II) and alpha 1(III). 5. Similarities between the extent of glycosylation of hydroxylysine residues in collagen-like regions in the subcomponent C1q molecule and that of the collagenous constituents of human glomerular basement membranes, aortic intima, skin A- and B-chains and of bovine anterior lens capsule are discussed.

Animals↗
PubMed1980

The effect of cycloheximide on the glycosylation of lactating-rabbit mammary glycoproteins.

1. Cycloheximide inhibited immediately the incorporation of L-[4,5-3H]leucine and D-]2-3H]mannose into mammary proteins, suggesting that the mannosylation of mammary glycoproteins requires the continued supply of newly synthesized polypeptides. 2. The incorporation of radioactivity from N-acetyl-D-[1-14C] glucosamine into protein was not inhibited until approx. 30 min after cycloheximide addition. Much (greater than 90%) of this radioactivity was present as N-acetylgalactosamine. 3. N-Glycosylation appears to be inhibited immediately by cycloheximide due to a lack of newly synthesized acceptor polypeptides, whereas O-glycosylation continues for 30 min, the time taken for acceptor peptides to move from their site of synthesis to the Golgi region and for completion of glycosylation. 4. There was a transient increase in the incorporation of mannose into lipid-linked oligosaccharide in the presence of cycloheximide, followed by a decrease in the radioactivity in this fraction. 5. The major lipid-linked oligosaccharide extracted from explants incubated for 2h in the presence of cycloheximide (6-7 monosaccharide units) was smaller than that extracted from control explants (10-12 monosaccharide units).

Animals↗