Simon R Haseley

Utrecht University, Utrecht, Utrecht, Netherlands

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Publications (14)40.39 Total impact

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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 01/2010; 33(29).
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    ABSTRACT: Two combinatorial glycopeptide libraries were synthesized on solid support via the "split-and-mix" method combined with the ladder synthesis strategy. The O-glycopeptide library contained Gal(beta1-O)Thr, whereas the S-,N-glycopeptide library contained both Gal(beta1-S)Cys and Gal(beta1-N)Asn. In this model study, the two libraries were screened against the fluorescently labeled lectin Ricinus communis agglutinin (RCA120). The screening results showed that both O- and S- or S-,N-glycopeptides were recognized by the lectin with similar amino acid recognition patterns. Surface plasmon resonance interaction studies demonstrated that both the selected S- or S-,N-glycopeptide hits and the O-glycopeptides bound to the lectin with a similar affinity. Structure 19, containing two glycosylated cysteine residues, bound to the receptor with the highest affinity (KA = 3.81 x 10(4) M(-1)), which is comparable to N-acetyllactosamine. Competition assays, in which some selected glycopeptides and methyl beta-d-galactopyranoside competed for the binding site of immobilized RCA120, showed that the glycopeptide-lectin interaction was carbohydrate-specific. Incubation of the O- and S-,N-glycopeptides with beta-galactosidase demonstrated the complete stability of S-,N-glycopeptides toward enzymatic degradation, whereas O-glycopeptides were not completely stable.
    Journal of Combinatorial Chemistry 01/2006; 8(6):812-9. · 4.93 Impact Factor
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    ABSTRACT: A new, powerful method is presented for screening the binding in real time and taking place under dynamic conditions of oligosaccharides to lectins. The approach combines an SPR biosensor and HPLC profiling with fluorescence detection, and is applicable to complex mixtures of oligosaccharides in terms of ligand-fishing. Labeling the oligosaccharides with 2-aminobenzamide ensures a detection level in the fmol range. In an explorative study the binding of RNase B-derived oligomannose-type N-glycans to biosensor-immobilized concanavalin A (Con A) was examined, and an affinity ranking could be established for Man(5)GlcNAc(2) to Man(9)GlcNAc(2), as monitored by HPLC. In subsequent experiments and using well-defined labeled as well as nonlabeled oligosaccharides, it was found that the fluorescent tag does not interfere with the binding and that the optimum epitope for the interaction with Con A comprises the tetramannoside unit Manalpha2Manalpha6(Manalpha3)Man[D(3)B(A)4'], rather than the generally accepted trimannoside Manalpha6 (Manalpha3)Man [B(A)4' or 4(4')3]. In a similar experimental setup, the interaction of various fucosylated human milk oligosaccharides with the fucose-binding lectin from Lotus tetragonolobus purpureaus was studied, and it appeared that oligosaccharides containing blood group H could selectively be retained and eluted from the lectin-coated surface. Finally, using the same lectin and a mixture of O-glycans derived from bovine submaxillary gland mucin, minor constituents but containing fucose could selectively be picked from the analyte solution as demonstrated by HPLC profiling.
    Glycobiology 06/2004; 14(5):373-86. · 3.54 Impact Factor
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    ABSTRACT: We present an in silico, structure-based approach for design and evaluation of conformationally restricted peptide-vaccines. In particular, we designed four cyclic peptides of ten or 11 residues mimicking the crystallographically observed beta-turn conformation of a predicted immunodominant loop of PorA from Neisseria meningitidis. Conformational correctness and stability of the peptide designs, as evaluated by molecular dynamics simulations, correctly predicted the immunogenicity of the peptides. We observed a peptide-induced functional antibody response that, remarkably, exceeded the response induced by the native protein in outer membrane vesicles, without losing specificity for related strains. The presented approach offers tools for a priori design and selection of peptide-vaccine candidates with full biological activity. This approach could be widely applicable: to outer membrane proteins of Gram-negative bacteria, and to other epitopes in a large range of pathogens.
    Journal of Molecular Biology 06/2003; 328(5):1083-9. · 3.91 Impact Factor
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    ABSTRACT: Long-chain polysialic acid (PSA) is expressed on the vertebrate neural cell adhesion molecule (NCAM) during neuronal plasticity. Its structural similarity to the capsular PSAs of some pathogenic bacteria has hampered the development of polysaccharide vaccines against meningitis. The antibodies formed during immunization require a long epitope for binding, and cross-react with host tissue PSA. The nature of the epitope and possible external effectors involved are still unclear. We have evaluated the interaction of PSA with its antibody mAb735 by surface plasmon resonance. The influences of PSA chain length, pH, temperature, ionic environment, and polyamines were also determined. The antibody binding affinity was found to dramatically increase with PSA chain length. A sub-nanomolar dissociation constant (K(D)=8.5 x 10(-10)M) was obtained for the binding of very long chain native MenB polysaccharides (approximately 200 Neu5Ac-residues). Colominic acid from Escherichia coli K1 (approximately 100 residues) and shorter polymers exhibited progressively weaker affinities. The antibody also bound tightly (K(D) approximately 5 x 10(-9)M) to polysialylated glycopeptides from human embryonal brain. The effects of pH and ionic strength suggested that the interaction is largely electrostatic. Ca2+ and Mn2+ ions promoted the observed surface plasmon resonance response in a concentration dependent fashion. Spermine increased the response in a similar way. Our results suggest that divalent cations and polyamines may play significant role in the regulation of the PSA epitope presentation in vivo.
    Molecular Immunology 12/2002; 39(7-8):399-411. · 2.65 Impact Factor
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    ABSTRACT: Glycosylation of Asn-52 of the alpha-subunit (alphaAsn-52) is required for bioactivity of the alphabeta-dimeric human chorionic gonadotropin (hCG), although at a molecular level the effect of the glycan at alphaAsn-52 is not yet understood. To study the role of this glycan for heterodimer stability, the beta-subunit was recombined in solution with either the alpha-subunit or the alpha-subunit enzymically deglycosylated at alphaAsn-52. Enzymic deglycosylation avoids modification of the glycans at alphaAsn-78 and disturbing the protein folding. The efficiency of recombination after 16 h is 80%, independent of whether alphaAsn-52 is glycosylated or not. The dissociation constant of the hCG complex, with or without the glycan at alphaAsn-52, is less than 1 x 10(-5) s(-1), indicating that the glycan at alphaAsn-52 does not contribute significantly to the stability of the dimer. CD and NMR spectra indicate a local conformational difference between both alphabeta-dimeric hCG variants, most probably involving amino acids of the hCG beta-subunit close to the glycan at alphaAsn-52. These data explain the native-like receptor-binding abilities of hCG lacking the glycan at alphaAsn-52. It is proposed that for bioactivity the glycan at alphaAsn-52 is necessary for inducing and stabilizing a conformational change in hCG upon binding to the receptor, resulting in activation of the signal-transduction pathway.
    Biochemical Journal 07/2002; 364(Pt 2):485-95. · 4.65 Impact Factor
  • 12/2001: pages 702-703;
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    ABSTRACT: Surface plasmon resonance (SPR) is an optical phenomenon occurring at a metal coated interface between two media of different refractive index, e.g., water and glass. Exploitation of this phenomenon for investigating biomolecular interactions has occurred since biomolecules can be attached to a chemically modified gold surface and that an interaction between the surface and other biomolecules in solution will affect the SPR of the system. A great deal of the literature on this subject has involved an investigation of protein-ligand interactions, but this chapter will review the use of this technique for investigating carbohydrate-ligand interactions.
    10/2001: pages 93-114;
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    ABSTRACT: Sponges (Porifera), the simplest and earliest multicellular organisms, are thought to have evolved from their unicellular ancestors about 1 billion years ago by developing cell-recognition and adhesion mechanisms to discriminate against "non-self." Consequently, they are used as models for investigating recognition phenomena. Cellular adhesion of marine sponges is an event involving adherence of extracellular proteoglycan-like molecules, otherwise known as aggregation factors (AFs). In a calcium-independent process the AFs adhere to the cell surface, and in a calcium-dependent process they exhibit AF self-association. A mechanism which has been implied but not definitely proven to play a role in the calcium-dependent event is self-recognition of defined carbohydrate epitopes. For the red beard sponge, Microciona prolifera, two carbohydrate epitopes, a sulfated disaccharide and a pyruvylated trisaccharide, have been implicated in cellular adhesion. To investigate this phenomenon a system has been designed, by using surface plasmon resonance detection, to mimic the role of carbohydrates in cellular adhesion of M. prolifera. The results show self-recognition of the sulfated disaccharide to be a major force behind the calcium-dependent event. The interaction is not simply based on electrostatic interactions, as other sulfated carbohydrates analyzed by using this procedure did not self-associate. Furthermore, the interaction is completely eradicated on substitution of Ca(2+) ions by either Mg(2+) or Mn(2+) ions. This physiologically relevant recognition mechanism confirms the existence of true carbohydrate self-recognition, and may have significant implications for the role of carbohydrates in cellular recognition of higher organisms.
    Proceedings of the National Academy of Sciences 08/2001; 98(16):9419-24. · 9.81 Impact Factor
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    ABSTRACT: The binding properties of a spacer-linked synthetic Sda tetrasaccharide β-d-GalpNAc-(1→4)-〚α-Neu5Ac-(2→3)〛-β-d-Galp-(1→4)-β-d-GlcpNAc-(1→O)-(CH2)5-NH2 (1), two tetrasaccharide mimics β-d-Galp-(1→4)-〚α-Neu5Ac-(2→3)〛-β-d-Galp-(1→4)-β-d-GlcpNAc-(1→O)-(CH2)5-NH2 (2) and β-D-GlcpNAc-(1→4)-〚α-Neu5Ac-(2→3)〛-β-D-Galp-(1→4)-β-d-GlcpNAc-(1→O)-(CH2)5-NH2 (3), and two trisaccharide mimics β-d-GalpNAc-(1→4)-3-O-(SO3H)-β-d-Galp-(1→4)-β-d-GlcpNAc-(1→O)-(CH2)5-NH2 (4) and β-d-GalpNAc-(1→4)-3-O-(CH2COOH)-β-d-Galp-(1→4)-β-d-GlcpNAc-(1→O)-(CH2)5-NH2 (5) with lectins from Dolichos biflorus (DBL), Maackia amurensis (MAL), Phaseolus limensis (PLL), Ptilota plumosa (PPL), Ricinus communis 120 (RCL120) and Triticum vulgaris (wheat germ agglutinin, WGA) have been investigated by surface plasmon resonance (SPR) detection. MAL, PPL, RCL120 and WGA did not display any binding activity with compounds 1–5. However, DBL and PLL, both exhibiting GalNAc-specificity, showed strong binding activity with compounds 1, 4 and 5, and 1, 3, 4 and 5, respectively. The results demonstrate that SPR is a very useful analysis system for identifying biologically relevant oligosaccharide mimics of the Sda determinant.
    Biochimie 07/2001; 83(7):653–658. · 3.14 Impact Factor
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    Biochimie 01/2001; 83(7). · 3.14 Impact Factor
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    ABSTRACT: Two galacturonic-acid-containing polysaccharide fractions (ChSS and P) were isolated from soybean meal and subjected to lithium treatment. The fragments obtained were analyzed by using monosaccharide and methylation analyses, and NMR spectroscopy. Lithium degradation of ChSS, followed by sodium borodeuteride reduction, hydrolysis, sodium borohydride reduction, and acetylation afforded alditol acetates, of which the labeled ones reflected residues linked to GalA. As followed from quantifications of the labeled and non-labeled alditols from each constituent monosaccharide by GLC-EIMS, 6 mol% of Ara, 22 mol% of Fuc, 13 mol% of Gal, 53 mol% of Rha, and 57 mol% of Xyl are glycosidically linked to GalA. Analysis of the lithium-treated polymer revealed that it contains arabinogalactan side chains linked to Rha O-4, which consist of a beta-(1 --> 4)-linked galactan substituted with highly branched arabinan chains. On average, an arabinogalactan chain contains up to 29 Gal and 25 Ara residues. Surface plasmon resonance was used to determine conditions for affinity chromatography. Furthermore, this technique confirmed the presence of terminal alpha-Fuc residues in ChSS. Polysaccharide P turned out to be relatively resistant to lithium degradation.
    Carbohydrate Research 11/2000; 328(4):539-47. · 2.04 Impact Factor
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    ABSTRACT: An accurate, rapid, and sensitive method for characterizing the carbohydrate binding properties of lectins using a BIAcore apparatus and the detection method of surface plasmon resonance is described. As a model study, the sialic acid binding lectins from Sambucus nigra and Maackia amurensis, which are specific for the epitopes Neu5Ac(alpha2-6)Gal and Neu5Ac(alpha2-3)Gal, respectively, were chosen as suitable candidates. Two systems, one for the analysis of oligosaccharides and the other for glycoproteins, were developed after a rigorous analysis and evaluation of such parameters as binding conditions, buffers, and regeneration conditions. The systems take into account nonspecific binding, using the respective denatured lectin as negative blank, and avoid loss of activity: regeneration of the surface using either 10 mM NaOAc (pH 4.3) buffer (oligosaccharide system) or 20 mM HCl (glycoprotein system). The specificity of the lectins is well illustrated, while the kinetics parameters are shown to be sensitive to subtle changes in the recognized epitopes, and to be affected by steric hindrance. Surface plasmon resonance is a suitable technique for the analysis and characterization of lectins.
    Analytical Biochemistry 11/1999; 274(2):203-10. · 2.58 Impact Factor
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    ABSTRACT: Surface plasmon resonance (SPR) is an optical phenomenon occurring at a metal coated interface between two media of different refractive index, e.g., water and glass. Exploitation of this phenomenon for investigating biomolecular interactions has occurred since biomolecules can be attached to a chemically modified gold surface and that an interaction between the surface and other biomolecules in solution will affect the SPR of the system. A great deal of the literature on this subject has involved an investigation of protein-ligand interactions, but this chapter will review the use of this technique for investigating carbohydrate-ligand interactions.

Publication Stats

176 Citations
40.39 Total Impact Points

Institutions

  • 1999–2010
    • Utrecht University
      • • Division of Biochemistry
      • • Division of Organic Chemistry and Catalysis
      • • Bijvoet Institute for Biomolecular Research
      Utrecht, Utrecht, Netherlands
  • 2002
    • University of Kuopio
      • Department of Biochemistry
      Kuopio, Eastern Finland Province, Finland