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H R Morris

Publications and source records attributed to H R Morris.

At least 109 records · Page 6Linked to original sources
PubMed1996

The occurrence of novel 9-O-sulfated N-glycolylneuraminic acid-capped alpha2-->5-Oglycolyl-linked oligo/polyNeu5Gc chains in sea urchin egg cell surface glycoprotein. Identification of a new chain termination signal for polysialyltransferase.

We report the isolation and structural characterization of an oligo/polysialic acid-containing glycopeptide fraction (designated ESP-Sia) prepared from the egg cell surface complex of the sea urchin, Hemicentrotus pulcherrimus, by exhaustive pronase treatment. The carbohydrate chains isolated from ESP-Sia were shown to consist of O-linked oligo/polysialic acid-containing glycan units and N-linked carbohydrate chains. The present studies have revealed that the O-linked oligo/polysialic acid-containing glycan chains derived from the ESP-Sia were similar to those present in egg jelly coat polysialylated glycoprotein in being composed of tandem repeats of N-glycolylneuraminic acid (Neu5Gc) glycosidically linked in a novel fashion through the glycolyl group, (-->5-OglycolylNeu5Gcalpha2-->)n. However, they differ from the egg jelly coat in two key respects. First, the average degree of polymerization of the oligo/polysialic acid chains of ESP-Sia is only 3; a value far lower than that found in the jelly coat glycoprotein (average degree of polymerization was about 20). Second, ESP-Sia is uniquely characterized by the presence of 9-O-sulfated N-glycolylneuraminic acid (Neu5Gc9HSO3) residues at the nonreducing termini of the (-->5-OglycolylNeu5Gcalpha 2-->)n chains. The terminal sialyl residues in the Neu5Gc9HSO3 alpha2-->(-->5-OglycolylNeu5Gcalpha2-->)n chains were totally resistant to exosialidases. The discovery of Neu5Gc9HSO3 as the nonreducing terminal residue of oligo/poly(-->5-OglycolylNeu5Gcalpha 2-->) group is especially noteworthy in that Neu5Gc9HSO3 appears to be of limited distribution among glycoconjugates. Following the earlier discovery of oligo/polysialic acid chains capped with KDN, i.e. KDN alpha2-->(-->8Neu5Gcalpha2-->)n, found in rainbow trout egg polysialoglycoproteins, it now appears that the sulfated Neu5Gc can serve a similar capping function.

Acetylation↗
PubMed1996

High sensitivity collisionally-activated decomposition tandem mass spectrometry on a novel quadrupole/orthogonal-acceleration time-of-flight mass spectrometer.

Consideration of the special problems encountered in ultra-high sensitivity biopolymer sequencing studies has led to the development of a novel quadrupole/erthogonal-acceleration time-of-flight tandem mass spectrometer described for the first time here. The performance characteristics of this new geometry are demonstrated, including fully resolved daughter-ion spectra with mass accuracies of 0.1 dalton, which allow removal of interpretation ambiguities and easy differentiation of charge states even in weak collisionally-activated decomposition tandem mass spectra. The instrument has been applied to a variety of biopolymer research problems, including the structure determination of major histocompatibility complex peptide antigens using liquid chromatography/electrospray mass spectrometry and nanoflow-electrospray tandem mass spectrometry, and sequencing capability in the low-femtomole and attomole ranges is demonstrated.

Amino Acid Sequence↗
PubMed1996

Isolation and identification of novel sulfated and nonsulfated oligosialyl glycosphingolipids from sea urchin sperm.

Novel sulfated and nonsulfated oligosialylglycosphingolipids were isolated from sperm of the sea urchin, Hemicentrotus pulcherrimus, and their structures were established as follows: [formula: see text] This provides the first evidence for the natural occurrence of a tetrasialic acid structure in glycosphingolipids. The finding of sulfated oligosialyl chains is especially noteworthy in that the sulfate group exclusively resides on the C-8 of the nonreducing terminal residues of oligo/polysialyl chains and that sulfation appears to be a termination signal for elongation of oligosialyl chains. Sulfation at the nonreducing terminal Neu5Ac residues of oligosialyl chains was also found to facilitate the formation of an inter-residue lactone between the carboxyl group at the nonreducing terminal sulfated Neu5Ac and the hydroxyl group at C-9 of the penultimate Neu5Ac residue. The long chain base was 4-hydroxysphinganine (t18:0) and the major fatty acid species were identified as C20:1, C21:1, and C22:1.

Animals↗
PubMed1996

Identification of disulphide bonds in the refolding of bovine pancreatic RNase A.

BACKGROUND: Comprehension of the rules that govern the folding process is still far from satisfactory, though it is nevertheless clear that all the information required to define the folding is encoded in the amino acid sequence. In proteins that contain disulphide bonds, folding is associated with disulphide bond formation. Protein species with different numbers of disulphides tend to accumulate during the process; these species can be trapped in a stable form, by quenching any remaining free SH groups, and then characterized in order to identify the disulphide bonds formed. RESULTS: The refolding pathway of reduced and denatured RNase A has been studied using mass spectrometric strategies which allow identification of the formation and rearrangement of disulphide bonds during the process. When reoxidation was carried out in the presence of B M urea, producing the classic "scrambled' RNase, three native and 11 non-native disulphide bonds were identified. When the reoxidation was performed under nondenaturing conditions, the formation of several well defined non-native as well as native S-S bonds was observed at early stages of the refolding process. Under appropriate conditions, all four native disulphide bonds were identified at later stages of refolding and non-native disulphides were greatly diminished or non-existent. This stage corresponded with the almost complete recovery of biological activity of the protein. CONCLUSIONS: The results presented here show that both native and non-native disulphide bonds are formed during the refolding of reduced and denatured RNase A in vitro under different experimental conditions. Essentially 14 disulphide bonds were observed of the 2B theoretically possible cysteine couplings. Although this number constitutes a significant fraction of the theoretical total, the occurrence of only a subset of disulphides clearly indicates that the formation of the S-S bridges does not occur at random, even when reoxidation takes place under denaturing conditions.

Animals↗
PubMed1996

Characterization of carbohydrate structural features recognized by anti-arabinogalactan-protein monoclonal antibodies.

Arabinogalactan-proteins (AGPs) are a diverse class of plant cell surface proteoglycans implicated in a range of fundamental processes associated with plant cell development. Anti-AGP monoclonal antibodies have been used extensively for the investigation of the developmental regulation of AGPs although virtually nothing is known about the structure of the carbohydrate epitopes recognised by these antibodies. In this report, a series of methyl glycosides of monosaccharides and a range of oligosaccharides that are elements of the carbohydrate component of AGPs have been investigated for recognition by previously derived anti-AGP monoclonal antibodies. No clear evidence was obtained for the involvement of terminal arabinofuranosides, nor of the galactan backbone, in the recognition of the glycan structure of AGPs by any of the antibodies used in this study. Interestingly, the most effective inhibitor of the binding of the monoclonal antibodies MAC207, JIM4 and JIM13 to exudate gum antigens was an acidic trisaccharide, isolated from a partial acid hydrolysate of gum karaya which has the structure: GlcA beta(1-->3) GalA alpha(1-->2)Rha, determined by a combination of FAB-MS, GC-MS and NMR spectroscopy.

Antibodies, Monoclonal↗
PubMed1996

A role for glycoconjugates in human development: the human feto-embryonic defence system hypothesis.

The mechanisms underlying the protection of the human embryo/fetus from the maternal immune response are poorly understood. Substantial evidence indicates that carbohydrate recognition plays a primary role in the sequestration of leukocytes during inflammatory processes, lymphocyte homing, and initial gamete binding. Our previous studies suggest a possible convergence in the types of carbohydrate sequences recognized during initial human gamete binding and immune/inflammatory cell interactions. Our more recent findings indicate that oligosaccharides participating in such processes are also associated with soluble glycoconjugates found in the human placenta, amniotic fluid, and decidua. We theorize that such glycoconjugates may abrogate the maternal immune/inflammatory response by blocking the primary adhesive interactions required for the expression of such activities. Foreign embryonic cells may also be protected by surface expression of oligosaccharide sequences that suppress immune effector cell action in a manner not dependent upon classical major histocompatibility (MHC) recognition. Glycoconjugates expressing selectin ligands may also manifest a potent contraceptive effect that may also be beneficial for both the mother and the developing embryo/fetus. This hypothesis provides a preliminary framework for understanding how temporally and spatially restricted immunosuppressive effects could be expressed in utero that protect the human embryo/fetus during this period of human development.

Animals↗
PubMed1996

Glycodelin from seminal plasma is a differentially glycosylated form of contraceptive glycodelin-A.

Glycodelin-A is a human amniotic fluid-derived glycoprotein with contraceptive and immunosuppressive activities. An immunoreactive form of glycodelin was detected in seminal plasma over a decade ago, but definitive characterization of this glycoprotein was not pursued. We considered it unlikely that the seminal plasma of fertile men would contain an appreciable amount of contraceptive glycodelin-A. To address this issue we purified seminal plasma glycodelin (glycodelin-S) and performed comparative studies with glycodelin-A. Glycodelin-S behaved differently when compared with glycodelin-A during sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and isoelectric focusing but identically after enzymatic deglycosylation. N-terminal sequencing of glycodelin-A and glycodelin-S gave identical results, and digestion with trypsin gave identical peptide fragments. The glycoproteins were also found to be indistinguishable from each other based upon immunological analyses. These results indicate that glycodelin-S and glycodelin-A have similar overall protein structure, suggesting the likelihood that these glycoproteins are differentially glycosylated forms of very similar proteins. This latter possibility is supported by lectin binding studies indicating that, unlike glycodelin-A, glycodelin-S does not manifest any affinity for lectins from Wisteria floribunda or Sambucus nigra. The results of sugar analysis and neuraminidase digestion also lead us to conclude that glycodelin-S and glycodelin-A are differentially glycosylated forms of similar proteins. Our evidence indicates that glycodelin-A mediated its biological activities via its unusual oligosaccharide sequences that are not associated with glycodelin-S. In lectin-immunoassay no appreciable amount of contraceptive glycodelin-A was found in the 22 seminal plasma samples studied.

Amidohydrolases↗
PubMed1995

Structural analysis of the oligosaccharides derived from glycodelin, a human glycoprotein with potent immunosuppressive and contraceptive activities.

Glycodelin, also known as placental protein 14 (PP14) or progesterone-associated endometrial protein (PAEP), is a human glycoprotein with potent immunosuppressive and contraceptive activities. In this paper we report the first characterization of glycodelin-derived oligosaccharides. Using strategies based upon fast atom bombardment and electrospray mass spectrometry we have established that glycodelin is glycosylated at Asn-28 and Asn-63. The Asn-28 site carries high mannose, hybrid and complex-type structures, whereas the second site is exclusively occupied by complex-type glycans. The major non-reducing epitopes in the complex-type glycans are: Gal beta 1-4GlcNAc (lacNAc), GalNAc beta 1-4GlcNAc (lacdiNAc), NeuAc alpha 2-6Gal beta 1-4GlcNAc (sialylated lacNAc), NeuAc alpha 2-6Gal beta 1-4GlcNAc (sialylated lacdiNAc), Gal beta 1-4(Fuc alpha 1-3)GlcNAc (Lewisx), and GalNAc beta 1-4(Fuc alpha 1-3)GlcNAc (lacdiNAc analogue of Lewisx). It is possible that the oligosaccharides bearing sialylated lacNAc or lacdiNAc antennae may manifest immunosuppressive effects by specifically blocking adhesive and activation-related events mediated by CD22, the human B cell associated receptor. Oligosaccharides with fucosylated lacdiNAc antennae have previously been shown to potently block selectin-mediated adhesions and may perform the same function in glycodelin. The potent inhibitory effect of glycodelin on initial human sperm-zona pellucida binding is consistent with our previous suggestion that this cell adhesion event requires a selectin-like adhesion process. This result also raises the possibility that a convergence between immune and gamete recognition processes may have occurred in the types of carbohydrate ligands recognized in the human.

Amino Acid Sequence↗
PubMed1995

A unique multifucosylated -3GalNAc beta 1-->4GlcNAc beta 1-->3Gal alpha 1- motif constitutes the repeating unit of the complex O-glycans derived from the cercarial glycocalyx of Schistosoma mansoni.

The entire surface of the cercarial stage of the human blood fluke Schistosoma mansoni is covered by a 1-microns thick, highly immunogenic, fucose-rich glycocalyx (GCX). Using strategies based on enzymatic, chemical, and mass spectrometric analysis, we have defined the structures of the major glycans released by reductive elimination from GCX. They comprise a heterogeneous population of multifocosylated complex oligosaccharides with the following nonreducing terminal sequences: [formula: see text] Our structural data suggest that these tri- to pentafucosylated epitopes are carried on type 1, R-->Gal beta-1-->3GalNAc, and type 2, R-->Gal beta 1-->3(R-->GlcNAc beta-1-->6)GalNAc, core structures via repeat units of (3GalNAc beta 1-->4(Fuc alpha 1-->2Fuc alpha 1-->2Fuc alpha 1-->3)GlcNAc beta-1-->3Gal alpha-->)n, where n is mainly 0 and 1, and all sugars are in the pyranose form. The proposed structure represents the first instance where an alpha-galactosylated beta-GalNAc(1-->4)-beta-GlcNAc sequence occurs as a repeating unit in a glycoprotein. It is also unique in being substituted with oligofucosyl appendages. The unusual oligosaccharide structures described here, particularly the potentially immunodominant oligofucosyl moieties, are most likely responsible for the known potency of GCX in modulating various immune responses including complement activation, B cell mitogenesis, and delayed type hypersensitivity in schistosomiasis.

Animals↗
PubMed1995

Inositol phosphate capping of the nonreducing termini of lipoarabinomannan from rapidly growing strains of Mycobacterium.

Previous studies have demonstrated that the nonreducing termini of the lipoarabinomannan (LAM) from Mycobacterium tuberculosis are extensively capped with mannose residues, whereas those from a fast growing Mycobacterium sp., once thought to be an attenuated strain of M. tuberculosis, are not. The noncapped LAM, termed AraLAM, is known to be more potent than the mannose-capped LAM (ManLAM) in inducing functions associated with macrophage activation. Using a combination of chemical and enzymatic approaches coupled with fast atom bombardment-mass spectrometry analysis, we demonstrated that LAMs from all M. tuberculosis strains examined (Erdman, H37Ra, and H37Rv), as well as the attenuated Mycobacterium bovis BCG strain, are mannose-capped with the extent of capping varying between 40 and 70%. The nonreducing termini of LAM from Mycobacterium leprae were also found to be capped with mannoses but at a significantly lower level. A novel inositol phosphate capping motif was identified on a minor portion of the otherwise uncapped arabinan termini of LAMs from the fast growing Mycobacterium sp. and Mycobacterium smegmatis ATCC 14468 and mc(2)155. In addition, an inositol phosphate tetra-arabinoside was isolated from among endoarabinase digestion products of AraLAM and was shown to induce tumor necrosis factor-alpha production. Accordingly, we concluded that AraLAM is characteristic of some rapidly growing Mycobacterium spp. It is distinct from ManLAMs of M. tuberculosis, M. bovis BCG, and Mycobacterium leprae not only in the absence of mannose-capping but also in containing some terminal inositol phosphate substituents which may account for its particular potency in inducing macrophage activation.

Antigens, Bacterial↗
PubMed1995

A new interpretation of the structure of the mycolyl-arabinogalactan complex of Mycobacterium tuberculosis as revealed through characterization of oligoglycosylalditol fragments by fast-atom bombardment mass spectrometry and 1H nuclear magnetic resonance spectroscopy.

Previous structural analysis of small oligosaccharide fragments had allowed the recognition of several small structural motifs within arabinogalactan, the dominant cell was structural polysaccharide of Mycobacterium tuberculosis. To determine how these motifs are connected to one another to form the complete polymer, oligosaccharide fragments containing up to 26 glycosyl residues were released by gentle acid hydrolysis of the per-O-methylated arabinogalactan, converted to fully per-O-alkylated oligoglycosylalditols, and purified by high-performance liquid chromatography, and the molecular weights and alkylation patterns of the resultant oligoglycosyl fragments were determined by fast atom bombardment mass spectrometry. The results, combined with previous studies, allowed further understanding of the intricate structural features of the nonreducing ends of arabinogalactan. Thus, the extended nonreducing ends of the arabinan were shown to consist of a tricosaarabinoside (23-mer). We reason that three such arabinan motifs are attached to the homogalactan component or arabinogalactan, which was previously shown to consist of alternating 5- and 6-linked beta-D-galactofuranosyl residues. Using the same approach as applied to the arabinan branches, an extended stretch of the galactan was isolated that consisted of at least 23 alternating beta-1,6 and beta-1,5 D-Galf residues, devoid of any branching, demonstrating that the points of attachment of the arabinan chains to galactan are close to the reducing end of galactan, which itself is linked to peptidoglycan via the linker disaccharide phosphate L-Rhap-(1-->3)-alpha-D-GlcNAc-P. By nuclear magnetic resonance analysis, the L-Rhap was shown to be in the alpha configuration. The long-chain alpha-alkyl-beta-hydroxy mycolic acids, known to occupy the 5-positions of both the terminal beta-D-Araf and internal 2-alpha-D-Araf residues of the terminal branched pentaarabinosyl motif, are now shown to be nonacylated at the beta-hydroxy function. Lack of acylation points to intramolecular hydrogen bonding between the beta-hydroxyl and carbonyl functions of the mycolic acid, providing a highly ordered arrangement of mycolic acids in accord with evolving models of the orientation of the cell wall polymers in mycobacterial cell walls. A revised model is proposed for the composition and orientation of the mycolyl-arabinogalactan in the cell walls of M. tuberculosis, which should increase our understanding of cell wall hydrophobicity, impermeability, and role in disease pathogenesis.

Alkylation↗
PubMed1995

Expression of de-N-acetyl-gangliosides in human melanoma cells is induced by genistein or nocodazole.

Neuraminic acid is the core structure of most known sialic acids. In natural systems, the amino group at the 5 position of neuraminic acid residues is usually assumed to be acylated. Previously, synthetic de-N-acetyl-gangliosides (with free amino groups at the 5 position of neuraminic acids) have been shown to modulate cellular proliferation and tyrosine phosphokinase reactions. While indirect evidence has suggested that traces of these molecules exist naturally in certain tumor cells, further exploration has been hampered by the lack of a system showing consistent expression at an easily detectable level. Using synthetic compounds as antigens, we have developed highly specific monoclonal antibodies against de-N-acetyl-GM3 and de-N-acetyl-GD3 that require both the free amino group and the exocyclic side chain of sialic acids for recognition. Cultured human melanoma cells showed low but variably detectable levels of reactivity with these antibodies. The ability of various biologically active molecules to stimulate this reactivity was explored. Of many compounds tested, only the tyrosine kinase inhibitor genistein induced reactivity in a dose-dependent manner. Antibody reactivity with ganglioside extracts from genistein-treated cells was abolished by chemical re-N-acetylation and/or truncation of sialic acid side chains by mild periodate oxidation. High performance thin layer chromatography immuno-overlay analysis confirmed the presence of the novel compound de-N-acetyl-GD3 in these extracts. Several other tyrosine kinase inhibitors tested did not give the same increase in de-N-acetyl-ganglioside expression. However, the microtubule inhibitor nocodazole caused a similar accumulation of these molecules, particularly in non-adherent cells expected to be arrested at metaphase. Thus, genistein may induce de-N-acetyl-ganglioside expression by virtue of its known ability to arrest cells in the G2M phase, rather than as a general consequence of tyrosine kinase inhibition. These studies also provide a system in which to analyze the enzymatic basis of de-N-acetyl-ganglioside expression and their potential roles as growth regulating molecules.

Antibodies, Monoclonal↗
PubMed1995

Structural definition of acylated phosphatidylinositol mannosides from Mycobacterium tuberculosis: definition of a common anchor for lipomannan and lipoarabinomannan.

Based on chemical analysis, we have previously concluded that the biologically important lipoarabinomannan (LAM) and lipomannan (LM) from Mycobacterium are multiglycosylated forms of the phosphatidylinositol mannosides (PIMs), the characteristic cell envelope mannophosphoinositides of mycobacteria. Using definitive analytical techniques, we have now re-examined the reported multiacylated nature of PIMs in order to gain a better insight into their possible roles as biosynthetic precursors of LM and LAM. High-sensitivity fast atom bombardment-mass spectrometry analyses of the perdeuteroacetyl and permethyl derivatives of PIMs from Mycobacterium tuberculosis and Mycobacterium leprae enabled us to define the exact fatty acyl compositions of the multiacylated, heterogeneous PIM families, notably the dimannoside (PIM2) and the hexamannoside (PIM6). Specifically, in conjunction with other chemical and gas chromatography-mass spectrometry (GC-MS) analyses, the additional C16 fatty acyl substituent on PIM2 and its lyso form were defined as attached to the C6 position of mannose. We also present evidence for triacylated mannophosphoinositide as a common lipid anchor for both LM and LAM, and further postulate that acylation of PIM2 may constitute a key regulatory step in their biosynthesis.

Acetylation↗
PubMed1995

Expression of new KDN-gangliosides in rainbow trout testis during spermatogenesis and their structural identification.

The developmental expression of 2-keto-3-deoxy-D-glycero-D-galacto-nononic acid-containing glycosphingolipids (KDN-gangliosides) in rainbow trout testis during spermatogenesis was studied using a monoclonal antibody, mAb.kdn3G, which recognizes the KDN alpha 2-->3Gal beta 1-->epitope. A major KDN-ganglioside found in mature sperm, (KDN)GM3, KDN alpha 2-->3Gal beta 1-->4Glc beta 1-->Cer (where Cer is ceramide), was expressed in testis throughout all stages of its maturation. On the contrary, four new KDN-gangliosides which were reactive with mAb.kdn3G were not detected in mature sperm, although they were identified in immature testis and expressed during spermatogenesis. The structures of these KDN-gangliosides were established by chemical, enzymatic and immunochemical methods as: (i) (KDN)GD1a, KDN alpha 2-->3Gal beta 1-->3GalNAc beta 1-->4(KDN alpha 2-->3)Gal beta 1-->4Glc beta 1-->Cer; (ii) (KDN, Neu5Ac)GD1a, KDN alpha 2-->3Gal beta 1-->3GalNAc beta 1-->4(Neu5Ac alpha 2-->3)Gal beta 1-->4Glc beta 1-->Cer and Neu5Ac alpha 2-->3Gal beta 1-->3GalNAc beta 1-->4(KDN alpha 2-->3)Gal beta 1-->4Glc beta 1-->Cer; (iii) (KDN) GD1 alpha, KDN alpha 2-->3Gal beta 1-->3(KDN alpha 2-->6)GalNAc beta 1-->4Gal beta 1-->4Glc beta 1-->Cer; and (iv) (KDN,Neu5Ac)GD1 alpha, KDN alpha 2-->3Gal beta 1-->3(Neu5Ac alpha 2-->6)GalNAc beta 1-->4Gal beta 1-->4Glc beta 1-->Cer. (KDN)GD1a and (KDN,Neu5Ac)GD1a first appeared at an early stage of spermatogenesis, but (KDN)GD1 alpha and (KDN,Neu5Ac)GD1 alpha were not expressed until 2 months prior to spermiation. While (KDN)GM3 was previously shown to contain only 4-sphingenine (d18:1) acylated with a C16:0 fatty acid, the new KDN-gangliosides discovered in this study were composed of 4-hydroxysphinganine (t18:0) or 4-sphingenine (d18:1), and were acylated with a C24:1 or C16:0 fatty acid. A possible function of these KDN-gangliosides is suggested.

Acylation↗
PubMed1995

The sulphated carbohydrate-protein linkage region isolated from chondroitin 4-sulphate chains of inter-alpha-trypsin inhibitor in human plasma.

Inter-alpha-trypsin inhibitor (ITI) in human plasma has a unique structural architecture composed of three polypeptide chains (H1, H2 and L chains), which are linked to each other through a chondroitin 4-sulphate chain. The structure of the carbohydrate-protein linkage region of the chondroitin 4-sulphate chain attached to the L chain was investigated. The peptide-chondroitin sulphate fraction was isolated by anion-exchange chromatography after exhaustive digestion with lysyl endopeptidase and then V8 protease. The chondroitin 4-sulphate chain was released from the peptides by beta-elimination using NaB3H4 and then digested with chondroitinase ABC. These treatments resulted in a single 3H-labelled hexasaccharide alditol fraction derived from the linkage region which had been associated with the L chain. Chemical and enzymatic analyses as well as fast-atom bombardment-mass spectrometry (FAB-MS) analysis revealed that the 3H-labelled hexasaccharide alditol had the following structure: delta HexA-alpha 1-3GalNAc(4-sulphate)beta 1-4GlcA beta 1-3Gal(4-sulphate)beta 1-3Gal beta 1-4Xyl-ol (where delta HexA is 4-deoxy-alpha-L-threo-hex-4-enepyranosyluronic acid and Xyl-ol is xylitol). The structure contained the novel 4-sulphated Gal residue, which was previously demonstrated in a linkage hexasaccharide isolated from chondroitin 4-sulphate of rat chondrosarcoma (Sugahara et al., J. Biol. Chem., 263, 10168-10174, 1988) and of whale cartilage (Sugahara et al., Eur. J. Biochem., 202, 805-811, 1991). The above disulphated hexasaccharide alditol was the only component detected in the linkage region fraction of the chondroitin 4-sulphate chain of ITI, which implies some biological significance of this novel structure.

Alpha-Globulins↗
PubMed1995

A precise structural analysis of a fertilization-associated carbohydrate-rich glycopeptide isolated from the fertilized eggs of euryhaline killi fish (Fundulus heteroclitus). Novel penta-antennary N-glycan chains with a bisecting N-acetylglucosaminyl residue.

A novel carbohydrate-rich sialoglycopeptide of apparent molecular mass approximately 6 kDa was isolated from the fertilized eggs of Fundulus heteroclitus (euryhaline killi fish). This glycopeptide is a member of the L-hyosophorin family, characterized by its high content of carbohydrate (80-90% by weight) and formed by depolymerization of the precursor glycopoly-protein (H-hyosophorin) upon fertilization. The structures of the N-glycan chains were unambiguously established by a combination of compositional analysis, methylation analysis, selective chemical degradation (periodate oxidation-Smith degradation and hydrazinolysis-nitrous acid deamination), enzymatic (peptide:N-glycosidase F, several beta-galactosidases, beta-hexosaminidase and alpha-galactosidase) digestions and instrumental analyses (1H-NMR and fast atom bombardment mass spectrometry) to have the novel and unique carbohydrate sequences, Gal alpha 1-->3(Gal beta 1-->4)Gal beta 1-->4GlcNAc beta 1--> and Gal alpha 1-->3(+/- GalNAc beta 1-->4GlcNAc beta 1-->3Gal beta 1-->4)Gal beta 1-->4GlcNAc beta 1-->. This study represents the first detailed investigation of the nature of bulky complex asparagine-linked penta-antennary glycans with a bisecting GlcNAc residue in glycoproteins. Expression of such bulky multiantennary glycan units on proteins may be essential during early embryogenesis.

Acetylglucosamine↗
PubMed1995

Antithrombin-TRI (Ala382 to Thr) causing severe thromboembolic tendency undergoes the S-to-R transition and is associated with a plasma-inactive high-molecular-weight complex of aggregated antithrombin.

An antithrombin (AT) variant Ala382 to Thr (AT-TRI) was identified by mass spectrometric techniques. The variant behaved as a substrate rather than a thrombin inhibitor, but, contrary to previously described P12 AT variants, AT-TRI, expressed as a heterozygous dominant trait, caused severe thromboembolic tendency beginning in their teens in affected members of an English family. In addition, it underwent the S-to-R conformational state transition as evidenced by an increased resistance to thermal denaturation on active centre cleavage, but did not react with a monoclonal antibody, 4C9, directed against a neoepitope that is present on complexed and cleaved normal AT. Antithrombin-TRI, in plasma, was also associated with an abnormal high molecular weight (M(r)) 194,000) component composed of non-covalently-linked antithrombin molecules. This component (D194) showed low affinity for heparin and was devoid of antithrombin progressive activity. D194, isolated by ammonium sulphate precipitation and three chromatographic steps (heparin Sepharose, ion exchange and immunoaffinity), migrated as a single band of M(r) 60,000 on SDS-PAGE under both reducing and non-reducing conditions and was recognized by monospecific anti-human antithrombin antibodies, but did not immunoreact with antibodies raised against a number of proteins including albumin and thrombin. The above data and the fact that the 15 N-terminal amino acids of this M(r) 60,000 band were identical to that of normal antithrombin indicated that the inactive D194 component was composed of aggregated antithrombin molecules, possibly antithrombin trimers. In conclusion, early adulthood severe thromboembolic tendency, failure to expose the 4C9 epitope, and presence of aggregated AT molecules in the plasma are characteristic features of AT-TRI not previously described in other ALA-382 THR mutations.

Adolescent↗