Complete 1H- and 13C-n.m.r. assignments for two sulphated oligosaccharide alditols of hen ovomucin

Potential role of ovomucin and its peptides in modulation of intestinal health: A review

Intestinal dysfunction, which may cause a series of metabolic diseases, has become a worldwide health problem. In the past few years, studies have shown that consumption of poultry eggs has the potential to prevent a variety of metabolic diseases, and increasing attention has been directed to the bioactive proteins and their peptides in poultry eggs. This review mainly focused on the biological activities of an important egg-derived protein named ovomucin. Ovomucin and its derivatives have good anti-inflammatory, antioxidant, immunity-regulating and other biological functions. These activities may affect the physical, biological and immune barriers associated with intestinal health. This paper reviewed the structure and the structure-activity relationship of ovomucin，the potential role of ovomucin and its derivatives in modulation of intestinal health are also summarized. Finally, the potential applications of ovomucin and its peptides as functional food components to prevent and assist in the pretreatment of intestinal health problems are prospected.

Sialylated O -Glycans from Hen Egg White Ovomucin are Decomposed by Mucin-degrading Gut Microbes

Ovomucin, a hen egg white protein, is characterized by its hydrogel-forming properties, high molecular weight, and extensive O -glycosylation with a high degree of sialylation. As a commonly used food ingredient, we explored whether ovomucin has an effect on the gut microbiota. O- Glycan analysis revealed that ovomucin contained core-1 and 2 structures with heavy modification by N -acetylneuraminic acid and/or sulfate groups. Of the two mucin-degrading gut microbes we tested, Akkermansia muciniphila grew in medium containing ovomucin as a sole carbon source during a 24 h culture period, whereas Bifidobacterium bifidum did not. Both gut microbes, however, degraded ovomucin O -glycans and released monosaccharides into the culture supernatants in a species-dependent manner, as revealed by semi-quantified mass spectrometric analysis and anion exchange chromatography analysis. Our data suggest that ovomucin potentially affects the gut microbiota through O -glycan decomposition by gut microbes and degradant sugar sharing within the community.

Sialic acid involves in the interaction between ovomucin and hemagglutinin and influences the antiviral activity of ovomucin

Ovomucin (OVM) plays an important role in inhibiting infection of various pathogens. However, this bioactivity mechanism is not much known. Here, the role of sialic acid in OVM anti-virus activity has been studied by ELISA with lectin or ligand. Structural changes of OVM after removing sialic acid were analyzed by circular dichroism and fluorescence spectroscopy. OVM could be binding to the hemagglutinin (HA) of avian influenza viruses H₅N₁ and H₁N₁, this binding was specific and required the involvement of sialic acid. When sialic acid was removed, the binding was significantly reduced 71.5% and 64.35%, respectively. Therefore, sialic acid was proved as a recognition site which avian influenza virus bound to. Meanwhile, the endogenous fluorescence and surface hydrophobicity of OVM removing sialic acid were increased and the secondary structure tended to shift to random coil. This indicated that OVM molecules were in an unfolded state and spatial conformation disorder raising weakly. Remarkably, free sialic acid strongly promoted OVM binding to HA and thereby enhanced the interaction. It may contribute to the inhibition of host cell infection, agglutinate viruses. This study can be extended to the deepening of passive immunization field.

Ovomucin - a glycoprotein with promising potential

Ovomucin, accounting for ∼3.5% of total egg white protein, is responsible for the thick gel characteristics of liquid egg white. Besides its excellent foaming and emulsion capacities, it possesses anti-viral, anti-bacterial, anti-tumor and other bioactivities. This paper reviews compositional, structural, physicochemical, functional and biological properties of ovomucin, as well as development of methods of extraction. As one of the least defined proteins in egg white, further study is required to characterize the structure and to explore its full potential in new applications as functional foods and nutraceuticals.

Glycopeptide derived from hen egg ovomucin has the ability to bind enterohemorrhagic Escherichia coli O157:H7

Ovomucin glycopeptide (OGP) was prepared by size exclusion chromatography after Pronase digestion of hen egg ovomucin, and the binding of OGP to foodborne pathogens (Bacillus cereus,Clostridium perfringens, Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enteritidis, Salmonella typhimurium, and Staphylococcus aureus) was investigaed. Binding assays with biotinylated bacteria as probes in microtiter plates showed that OGP bound to only E. coli O157:H7 among these foodborne pathogens. Periodate treatment markedly reduced the binding ability, indicating that E. coli O157:H7 bound to carbohydrate moieties of OGP. Lectin blot analysis with Maackia amurensis (MAA) and Sambucus nigra (SNA), which are specific for oligosaccharides containing sialic acid, revealed their binding sites in OGP were similar to the E. coli O157:H7 binding sites that were probed with biotinylated E. coli O157:H7 after Western blotting of OGP. Sialydase treatment of OGP abolished its ability to bind E. coli O157:H7, demonstrating that sialic acid played an important role in the binding. These results suggest that OGP has E. coli O157:H7-specific binding sites that consist of sialic acid. On the basis of these properties, OGP has the potential to be an ingredient with a protective effect against E. coli O157:H7 infection and to be a novel probe for the detection of E. coli O157:H7 in the food hygiene field.

High prevalence of 2-mono- and 2,6-di-substituted manol-terminating sequences among O-glycans released from brain glycopeptides by reductive alkaline hydrolysis

Di- to heptasaccharides isolated from total nondialyzable brain glycopeptides after release by alkaline borohydride treatment have been subjected to mass spectrometric and nuclear magnetic resonance spectroscopic analyses supplemented by TLC-MS analyses of derived neoglycolipids. A family of Manol-terminating oligosaccharides has been revealed which includes novel sequences with a 2, 6-disubstituted Manol: In contrast to the Manol-terminating HNK-1 antigen-positive chains described previously that occur as a minor population [Yuen, C.-T., Chai, W., Loveless, R.W., Lawson, A.M., Margolis, R.U. & Feizi, T. (1997) J. Biol. Chem. 272, 8924-8931], the above oligosaccharides are abundant. The ratio of these compounds to the classical N-acetylgalactosaminitol-terminating oligosaccharides is about 1 : 3. Thus, there appears to be in higher eukaryotes a major alternative pathway related to the yeast-type protein O-mannosylation, the enzymatic basis and functional importance of which now require investigation.

Structural study on a sulfated polysaccharide-peptidoglycan complex produced by Arthrobacter sp

The structure of a sulfated polysaccharide-peptidoglycan complex (SP-PG) produced by Arthrobacter sp. was analyzed by NMR spectroscopy. In addition, oligosaccharide fragments of the SP-PG-L obtained by HF degradation were analyzed by NMR spectroscopy. These findings indicated that the sulfated polysaccharide (SP) contains a repeating unit composed of two galactofuranosides and a glucopyranoside. The main chain of the trisaccharide is [-->6) beta-D-Galf(1-->6)-beta-D-Galf(1-->ln, with beta-D-Glcp linked to one of the Galfs through a (1-->2) linkage. The sulfated positions of the trisaccharide were identified as C-3 and C-5 of the beta-glucosylated Galf residues, and C-2 or C-3 of the other Galf residue.

Molecular cloning and characterization of an N-acetylglucosamine-6-O-sulfotransferase

We isolated a cDNA clone encoding mouse N-acetylglucosamine-6-O-sulfotransferase based on sequence homology to the previously cloned mouse chondroitin 6-sulfotransferase. The cDNA clone contained an open reading frame that predicts a type II transmembrane protein composed of 483 amino acid residues. The expressed enzyme transferred sulfate to the 6 position of nonreducing GlcNAc in GlcNAcbeta1-3Galbeta1-4GlcNAc. Galbeta1-4GlcNAcbeta1-3Galbeta1-4GlcNAc and various glycosaminoglycans did not serve as acceptors. Expression of the cDNA in COS-7 cells resulted in production of a cell-surface antigen, the epitope of which was NeuAcalpha2-3Galbeta1-4(SO4-6)GlcNAc; double transfection with fucosyltransferase IV yielded Galbeta1-4(Fucalpha1-3)(SO4-6)GlcNAc antigen. The sulfotransferase mRNA was strongly expressed in the cerebrum, cerebellum, eye, pancreas, and lung of adult mice. In situ hybridization revealed that the mRNA was localized in high endothelial venules of mesenteric lymph nodes. The sulfotransferase was concluded to be involved in biosynthesis of glycoconjugates bearing the 6-sulfo N-acetyllactosamine structure such as 6-sulfo sialyl Lewis X. The products of the sulfotransferase probably include glycoconjugates with intercellular recognition signals; one candidate of such a glycoconjugate is an L-selectin ligand.

Structural studies on a sulfated polysaccharide from an Arthrobacter sp. by NMR spectroscopy and methylation analysis

Structural characterization of a sulfated polysaccharide peptidoglycan complex (SP-PG) from an Arthrobacter sp. was performed by NMR spectroscopy and methylation analysis. In order to simplify the analyses, the desulfated SP-PG was used. NMR spectroscopy revealed the presence of a trisaccharide repeating unit and a disaccharide repeating unit. The trisaccharide unit was composed of two galactofuranosides and one glucopyranoside, and the disaccharide unit was of two galactopyranosides, as shown below. The methylation analysis showed that the polysaccharide consists mainly of a 4-linked galactopyranoside, a 6-linked galactopyranoside, a 6-linked galactofuranoside, a 2,6-linked galactofuranoside, a terminal galactopyranoside and a terminal glucopyranoside. These findings confirmed the structure indicated by the NMR spectroscopy. The repeating units determined in this study are novel.

Structures of sulfated oligosaccharides isolated from the respiratory mucins of a non-secretor (O, Le(a + b -)) patient suffering from chronic bronchitis

Mucin glycopeptides were prepared from the respiratory mucus of a non-secretor, chronic bronchitic patient with blood group O, Le(a + b-). Oligosaccharides were released by alkaline borohydride treatment and purified by anion-exchange chromatography, size-exclusion chromatography and high performance anion-exchange chromatography. Structural studies employed 400-MHz 1H-NMR spectroscopy and matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS). Nine monosulfated oligosaccharides ranging in size from tetra- to hexasaccharide, were fully characterized in this study. The sulfate group occurs either on the C-3 of a terminal galactose residue or on the C-6 of a N-acetylglucosamine residue. In keeping with the non-secretor status of the patient, no structure with an (alpha 1-2)-linked fucose residue was found. Five of the structures had fucose present in (alpha 1-3)-linkage in the X determinant, while only one oligosaccharide (compound 7b) was seen with fucose (alpha 1-4)-linked in the Le(a) determinant. Eight structures isolated from the mucins of the non-secretor patient had not been found previously in the respiratory mucins; they are listed below.

Structural analysis of the oligosaccharide-alditols released by reductive beta-elimination from oviducal mucins of Rana temporaria

The carbohydrate chains of the mucins which constitute the jelly coat surrounding the eggs of Rana temporaria were released by alkaline borohydride treatment. Neutral and acidic oligosaccharide-alditols were purified by ion-exchange chromatography and HPLC. From the structural analysis, based upon 1H and 13C-NMR spectroscopy in combination with MALDI-TOF, the following glycan units are proposed.

O-linked protein glycosylation structure and function

There has been a recent resurgence of interest in the post-translational modification of serine and threonine hydroxyl groups by glycosylation, because the resulting O-linked oligosaccharide chains tend to be clustered over short stretches of peptide and hence they can present multivalent carbohydrate antigenic or functional determinants for antibody recognition, mammalian cell adhesion and microorganism binding. Co-operativity can greatly increase the affinity of interactions with antibodies or carbohydrate binding proteins. Thus, in addition to their known importance in bearing tumour associated antigens in the gastrointestinal and respiratory tracts, glycoproteins with O-linked chains have been implicated as ligands or co-receptors for selectins (mammalian carbohydrate binding proteins). Microorganisms may have adopted similar mechanisms for interactions with mammalian cells in infection, by having relatively low affinity ligands (adhesins) for carbohydrate binding, which may bind with higher affinity due to the multivalency of the host ligand and which are complemented by other virulence factors such as interactions with integrin-type molecules. In addition to specific adhesion signals from O-linked carbohydrate chains, multivalent O-glycosylation is involved in determining protein conformation and forming conjugate oligosaccharide-protein antigenic, and possible functional determinants.

Enzyme-aided construction of medium-sized alditols of complete O-linked saccharides. The constructed hexasaccharide alditol Gal beta 1-4GlcNAc beta 1-6Gal beta 1-4GlcNAc beta 1-6(Gal beta 1-3)GalNAc-ol resists the action of endo-beta-galactosidase from Bacteroides fragilis

We have constructed by enzyme-aided in vitro synthesis a hexasaccharide alditol Gal beta 1-4GlcNAc beta 1-6Gal beta 1-4GlcNAc beta 1-6(Gal beta 1-3) GalNAc-ol and shown that it resists the action of endo-beta-galactosidase from Bacteroides fragilis under conditions where a related pentasaccharide alditol, GlcNAc beta 1-3Gal beta 1-4GlcNAc beta 1-6(Gal beta 1-3)GalNAc-ol, was completely cleaved. Together with earlier results from this laboratory, our present data imply that endo-beta-galactosidase from B. fragilis, apparently, can be used to distinguish between GlcNAc beta 1-6Gal and GlcNAc beta 1-3Gal units within linear backbone sequences of all known types of oligo-(N-acetyllactosamino)glycans.

1H-and 13C-n.m.r. spectroscopy of 2-oxo-3-deoxy-D-glycero-D- galactononulosonic acid-containing oligosaccharide-alditols bearing Lewis X, Lewis Y and A-Lewis Y determinants isolated from the jelly coat of Pleurodeles waltl eggs

Three acidic oligosaccharide-alditols carrying Lewis X, Lewis Y and A-Lewis Y determinants were isolated from the jelly coat of Pleurodeles waltl eggs. These compounds possess the following structures. Gal beta 1-4(Fuc alpha 1-3)GlcNAc beta 1-3[2-oxo-3-deoxy-D- glycero-D-galactononulosonic acid (KDN)alpha 2-6] GalNAc-ol; Fuc alpha 1-2Gal beta 1-4(Fuc alpha 1-3)GlcNAc beta 1-3(KDN alpha 2-6) GalNAc-ol and Fuc alpha 1-2(GalNAc alpha 1-3)Gal beta 1-4(Fuc alpha 1-3)GlcNAc beta 1-3(KDN alpha 2-6)GalNAc-ol. The complete 1H-n.m.r.-spectrum assignment for the three compounds and the 13C-n.m.r. analysis of the A-Lewis Y determinant-containing heptasaccharide are reported.

1H and 13C-NMR assignments for sialylated oligosaccharide-alditols related to mucins. Study of thirteen components from hen ovomucin and swallow nest mucin

Four hundred MHz 1H-NMR and 100 MHz 13C-NMR spectra of thirteen sialylated oligosaccharide-alditols isolated from hen ovomucin and swallow nests (Collocalia mucin) were studied. The resonance assignments were determined by combining multiple-relayed coherence-transfer chemical-shift-correlated spectroscopy (multiple-Relay-Cosy) and 1H/13C chemical-shift-correlated 2-D experiments.

Characterization of a novel type of chain-terminator Gal beta 1-6Gal beta 1-4)GlcNAc in an oligosaccharide related to N-glycosylated protein glycans isolated from GM1 the urine of patients with gangliosidosis

Two new oligosaccharides were isolated from the urine of a patient with GM1 gangliosidosis. Final purification of the oligosaccharides was accomplished by capillary supercritical fluid chromatography. Structural analysis was by chemical analysis, chemical-ionization mass spectrometry and 400-MHz 1H-NMR spectroscopy, leading to two primary structures. The first is derived from a classical triantennary N-acetyllactosamine-type glycan: Gal beta 1-4GlcNAc beta 1-4(Gal beta 1-4GlcNAc beta 1-2)Man alpha 1-3Man beta 1-4GlcNAc. The second is unusual with a terminal disaccharide Gal beta 1-6Gal, which had not yet been described for glycans of the N-acetyllactosamine type: Gal beta 1-6Gal beta 1-4GlcNAc beta 1-2Man alpha 1-6Man beta 1-4GlcNAc.

Structure of two sulphated oligosaccharides from respiratory mucins of a patient suffering from cystic fibrosis. A fast-atom-bombardment m.s. and 1H-n.m.r. spectroscopic study

Human respiratory-mucin glycopeptides were isolated from the sputum of a patient suffering from cystic fibrosis. They were subjected to treatment with alkaline borohydride. Application of ion-exchange chromatography afforded carbohydrate fractions containing sulphate. One of these fractions containing a mixture of sulphated oligosaccharides was subsequently submitted to gel-filtration chromatography and h.p.l.c. Two sulphated oligosaccharide-alditols, A and B, were prepared; their structure was determined by means of 400 MHz 1H-n.m.r. spectroscopy and fast-atom-bombardment m.s. They had a core type 2 and the sulphate was 3-linked to a terminal galactose residue: (Formula; see text)

Symbiotic host-specificity of Rhizobium meliloti is determined by a sulphated and acylated glucosamine oligosaccharide signal

Rhizobia are symbiotic bacteria that elicit the formation on leguminous plants of specialized organs, root nodules, in which they fix nitrogen. In various Rhizobium species, such as R. leguminosarum and R. meliloti, common and host-specific nodulation (nod) genes have been identified which determine infection and nodulation of specific hosts. Common nodABC genes as well as host-specific nodH and nodQ genes were shown recently, using bioassays, to be involved in the production of extracellular Nod signals. Using R. meliloti strains overproducing symbiotic Nod factors, we have purified the major alfalfa-specific signal, NodRm-1, by gel permeation, ion exchange and C18 reverse-phase high performance liquid chromatography. From mass spectrometry, nuclear magnetic resonance, (35)S-labelling and chemical modification studies, NodRm-1 was shown to be a sulphated beta-1,4-tetrasaccharide of D-glucosamine (Mr 1,102) in which three amino groups were acetylated and one was acylated with a C16 bis-unsaturated fatty acid. This purified Nod signal specifically elicited root hair deformation on the homologous host when added in nanomolar concentration.

Complete analysis of the 1H- and 13C-NMR spectra of four blood-group A active oligosaccharides

The fully assigned 1H and 13C-NMR spectra of four group A oligosaccharides by use of multiple-relayed, coherence-transfer chemical-shift-correlated spectroscopy (multiple-RELAY-COSY) and 1H-/13C-correlation spectroscopy are reported. These analyses were performed on the following compounds: III-A; GalNAc alpha 1-3[Fuc alpha 1-2]Gal: VI-A; GalNAc alpha 1-3[Fuc alpha 1-2]Gal beta 1-3[Fuc alpha 1-4]GlcNAc beta 1-3Gal: VII-A-1; GalNAc alpha 1-3[Fuc alpha 1-2]Gal beta 1-3[Fuc alpha 1-4]GlcNAc beta 1-3Gal beta 1-1Glycerol: VII-A-2; GalNAc alpha 1-3[Fuc alpha 1-2]Gal beta 1-3[Fuc alpha 1-4]GlcNAc beta 1-3Gal beta 1-4Glc.