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  • 1. Andre, Sabine
    et al.
    Pei, Zichao
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Siebert, Hans-Christian
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Gabius, Hans-Joachim
    Glycosyldisulfides from Dynamic Combinatorial Libraries as O-Glycoside Mimetics for Plant and Endogenous Lectins: Their Reactivities in Solid-Phase and Cell Assays and Conformational Analysis by Molecular Dynamics Simulations2006Inngår i: Bioorganic & Medicinal Chemistry, ISSN 0968-0896, Vol. 14, s. 6314-6326Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Dynamic combinatorial library design exploiting the thiol-disulfide exchange readily affords access to glycosyldisulfides. In order to reveal lectin-binding properties of this type of non-hydrolyzable sugar derivative, libraries originating from a mixture of common building blocks of natural glycans and thiocompounds were tested against three plant agglutinins with specificity to galactose, fucose or N-acetylgalactosamine, respectively, in a solid-phase assay. Extent of lectin binding to matrix-immobilized neoglycoprotein presenting the cognate sugar could be reduced, and evidence for dependence on type of carbohydrate was provided by dynamic deconvolution. Glycosyldisulfides also maintained activity in assays of increased physiological relevance, that is, using native tumor cells and also adding to the test panel an endogenous lectin (galectin-3) involved in tumor spread and cardiac dysfunction. N-Acetylgalactosamine was pinpointed as the most important building block of libraries for the human lectin and the digalactoside as most potent compound acting on the toxic mistletoe agglutinin which is closely related to the biohazard ricin. Because this glycosyldisulfide, which even surpasses lactose in inhibitory capacity, rivals thiodigalactoside as inhibitor, their degrees of intramolecular flexibility were comparatively analyzed by computational calculations. Molecular dynamics runs with explicit consideration of water molecules revealed a conspicuously high degree of potential for shape alterations by the disulfide's three-bond system at the interglycosidic linkage. The presented evidence defines glycosyldisulfides as biologically active ligands for lectins

  • 2.
    Dong, Hai
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Pei, Zhichao
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Angelin, Marcus
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Byström, Styrbjörn
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Efficient Synthesis of β-D-Mannosides and β-D-Talosides by Double Parallel or Double Serial Inversion2007Inngår i: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 72, nr 10, s. 3694-3701Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A neighboring equatorial ester group plays a highly important role in the Lattrell-Dax (nitrite-mediated) carbohydrate epimerization reaction, inducing the formation of inversion compounds in good yields. On the basis of this effect, efficient synthetic routes to beta-D-mannosides and beta-D-talosides, from the corresponding beta-D-galactosides and beta-D-glucosides, have been designed. The present routes are based on multiple regioselective acylation via the respective stannylene intermediates, followed by inversions to the corresponding manno- and talopyranoside structures by nitrite or acetate substitution. It was found that the ester group was able to induce the inversion of its two neighboring groups in high yields following either a double parallel or a double serial inversion process. By combination of direct inversion, and neighboring- as well as remote-group participation, several beta-D-mannoside and beta-D-taloside derivatives were very conveniently obtained in good yields.

  • 3.
    Dong, Hai
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Pei, Zhichao
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Byström, Styrbjörn
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Reagent-dependent regioselective control in multiple carbohydrate esterifications2007Inngår i: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 72, nr 4, s. 1499-1502Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Regioselective control in organotin-mediated multiple acylation of carbohydrates is presented. The acylation reagent could be efficiently used to direct the product formation. Reagent-dependent thermodynamic and kinetic control and dynamic assistance mechanisms are suggested, resulting in the efficient preparation of building blocks that normally require many steps with traditional synthesis.

  • 4.
    Dong, Hai
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Pei, Zhichao
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Stereospecific Ester Activation in Nitrite-Mediated Carbohydrate Epimerization2006Inngår i: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 71, nr 8, s. 3306-3309Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Lattrell-Dax method of nitrite-mediated substitution of carbohydrate triflates is an efficient method to generate structures of inverse configuration. In the present study, epimerization of gluco- and galactopyranoside derivatives to the corresponding allo- and gulopyranoside structures by triflation/nitrite treatment has been investigated. It was found that a neighboring ester group was essential for the reactivity of the nitrite-mediated triflate, inversion. Furthermore, a good inversion yield also depended on the relative configuration of the neighboring ester group to the triflate. Only with the ester group in the equatorial position, whatever the configuration of the triflate, did the reaction proceed smoothly, whereas a neighboring axial ester group proved largely inefficient. The results were subsequently used to predict the inversion of glucopyranoside derivatives to the mannopyranoside epimers.

  • 5.
    Dong, Hai
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Pei, Zhichao
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Supramolecular activation in triggered cascade inversion2008Inngår i: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, s. 1359-1361Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An unexpected activation effect from combinations of anionic reagent and amine base resulted in dramatic rate enhancements in multiple carbohydrate cascade inversion.

  • 6. Harnish, B.
    et al.
    Robinson, J. T.
    Pei, Zhichao
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Yan, Mingdi
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    UV-cross-linked poly(vinylpyridine) thin films as reversibly responsive surfaces2005Inngår i: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 17, nr 16, s. 4092-4096Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report that UV-cross-linked poly(4-vinylpyridine) (P4VP) films acted as reversibly responsive coatings that controlled surface wettability and swelling toward external stimuli: solvent and pH. The polymer films were prepared simply by spin-coating a solution of P4VP followed by UV irradiation. These cross-linked films, when treated with chloroform, showed similar to 31% increase in film thickness whereas films extracted with methylene chloride or n-butanol exhibited a slight decrease. The increase in film thickness was due to the protonation of pyridyl groups by hydrogen chloride resulting from the photodegeneration of chloroform. The film expanded to minimize repulsion around the charged centers. This hypothesis was further confirmed by exposing the cross-linked film to hydrogen chloride vapor. The film expanded similar to 37% whereas no thickness increase was observed for films exposed to ammonia or methanol vapors. The extent of swelling was monitored in situ using a quartz crystal microbalance sensor. Large oscillation frequency shifts were detected when the UV-cross-linked P4VP film was exposed to acidic buffer solutions. The changes were rapid, and the effect was reversible.

  • 7.
    Larsson, Rikard
    et al.
    KTH, Tidigare Institutioner, Kemi.
    Pei, Zhichao
    KTH, Tidigare Institutioner, Kemi.
    Ramström, Olof
    KTH, Tidigare Institutioner, Kemi.
    Catalytic Self-Screening of Cholinesterase Substrates from a Dynamic Combinatorial Thioester Library2004Inngår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 43, nr 28, s. 3716-3718Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Simply the best: Dynamic combinatorial chemistry coupled to enzyme catalysis was used to identify enzyme substrates in a library constructed from a series of thioesters and thiols by transesterification. The library was directly coupled to the catalytic action of acetylcholinesterase, which selectively hydrolyzed the best substrate candidates (see schematic representation). The process allowed rapid identification of discrete substrates.

  • 8.
    Pei, Yuxin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Yu, Hui
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Pei, Zhichao
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Theurer, Matthias
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Ammer, Carolin
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    André, Sabine
    Gabius, Hans-Joachim
    Yan, Mingdi
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Photoderivatized polymer thin films at quartz crystal microbalance surfaces: Sensors for carbohydrate-protein interactions2007Inngår i: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 79, nr 18, s. 6897-6902Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Photoderivatized polymer-coated gold surfaces have been developed following a perfluorophenylazide-based double ligation strategy. Gold-plated quartz crystal microbalance (QCM) crystals were initially covalently functionalized with a monolayer of poly(ethylene glycol) (PEG), using photo-or thermolytic nitrene formation and insertion. The polymer surfaces were subsequently used as substrates for photoinsertion of carbohydrate-derivatized photoprobes, yielding different recognition motifs for selective protein binding. The resulting robust and biocompatible sensor surfaces were applied to a flow-through QCM instrument for monitoring lectin-carbohydrate interactions in real time. The results clearly show the predicted lectin selectivity, demonstrating the applicability of the approach.

  • 9.
    Pei, Zhichao
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Carbohydrate Synthesis and Study of Carbohydrate-Lectin Interactions Using QCM Biosensors and Microarray Technologies2006Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Interactions between carbohydrates and proteins are increasingly being recognized as crucial in many biological processes, such as cellular adhesion and communication. In order to investigate the interactions of carbohydrates and proteins, the development of efficient analytic technologies, as well as novel strategies for the synthesis of carbohydrates, have to be explored. To date, several methods have been exploited to analyze interactions of carbohydrates and proteins, for example, biosensors, nuclear magnetic resonance (NMR); enzyme-linked immunosorbent assays (ELISA), X-ray crystallography and array technologies. This thesis describes the development of novel strategies for the synthesis of carbohydrates, as well as new efficient strategies to Quartz Crystal Microbalance- (QCM-) biosensors and carbohydrate microarrays technologies. These methodologies have been used to probe carbohydrate-lectin-interactions for a range of plant and animal lectins.

    Fulltekst (pdf)
    FULLTEXT01
  • 10.
    Pei, Zhichao
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Aastrup, Teodor
    Anderson, Henrik
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Redox-Responsive and Calcium-Dependent Switching of Glycosyldisulfide Interactions with Concanavalin A2005Inngår i: Bioorganic & Medicinal Chemistry Letters, ISSN 0960-894X, E-ISSN 1464-3405, Vol. 15, s. 2707-2710Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Glycosyldisulfides can interact efficiently with carbohydrate-binding entities. This has been shown for a range of thiosaccharide dimers when tested for their effects against the lectin Concanavalin A using a modified quartz crystal microbalance-technique. Contrary to the thiosaccharide monomers, showing no significant binding up to 10 mM, several of the dimers showed IC50-values in the low millimolar range. Three of the glycosyldisulfides tested also displayed very high positive apparent cooperativity effects that were found to be both calcium-dependent and redox-responsive.

  • 11.
    Pei, Zhichao
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Andersson, Henrik
    Aastrup, Teodor
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Study of Real-time Lectin–Carbohydrate Interactions on the Surface of a Quartz Crystal Microbalance2005Inngår i: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 21, nr 1, s. 60-66Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A quartz crystal microbalance (QCM) biosensor system for lectin-carbohydrate interactions has been developed. Yeast mannan was immobilised on polystyrene-coated quartz crystals, and interactions tested with the lectin concanavalin A (Con A). The biosensor could be easily operated, where mannan immobilisation and all binding analyses were performed in real-time using a flow-through system. The apparent binding constant for yeast mannan to Con A was estimated to be 0.4 μM, well in accordance to reported literature values. In addition, the effective concentration values (EC50-values) for a series of mannose/mannoside ligands, acting as competitors to the mannan/Con A interaction, were determined to range from 0.18 to 5.3 mM, in good correlation with a related enzyme-labelled lectin assay (ELLA) protocol

  • 12.
    Pei, Zhichao
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Dong, Hai
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Caraballo, Rémi
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Synthesis of Positional Thiol Analogs of β-D-Galactopyranose2007Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, Vol. 29, s. 4927-4934Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Approaches toward the synthesis of thio- beta -D -galactose derivatives are described. These compounds were prepared from the parent carbohydrates: D-galactose, methyl P-D-galactoside and methyl P-D-glucoside, respectively. It was found that not only the strategies of protecting group introduction and selective deprotection, but also the choices of solvent and nucleophilic reagent concentration were crucial to allow the efficient introduction of sulfur at different positions of the galactose ring. The effects from the solvent, the nucleophilic reagent concentration, and the protecting group patterns have been investigated. The results clearly show that ester protecting groups play highly important roles for the synthesis of thio-containing carbohydrates, requiring nonpolar solvents to suppress the neighboring group participation. For the Lattrell-Dax (nitrite -mediated) inversion reaction, employed in the synthetic route to the 2-thio-beta-D-galactoside, intramolecular nucleophilic attack, as well as stronger stereospecific ester activation, are necessary to overcome hindrance from 4,6-O-benzylidene protection.

  • 13.
    Pei, Zhichao
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Dong, Hai
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Solvent-dependent, kinetically controlled stereoselective synthesis of 3- and 4- thioglycosides2005Inngår i: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 70, nr 17, s. 6952-6955Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Facile approaches to prepare 3- and 4-thioglycosides of the galacto, gulo, and gluco type from the parent triflates are presented. The dependencies of the solvent and the protecting group pattern, as well as the configuration of the neighboring and leaving groups, have been studied for these reactions. The results clearly show that the efficient stereo-selective synthesis of methyl 3-thin-galactoside depends highly on the solvent and the nucleophile concentration.

  • 14.
    Pei, Zhichao
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Larsson, Rikard
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Aastrup, Teodor
    Attana AB.
    Anderson, Henrik
    Uppsala University, Ångström Laboratory, Solid State Electronics.
    Lehn, Jean-Marie
    ISIS-Université Louis Pasteur.
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Quartz crystal microbalance bioaffinity sensor for rapid identification of glycosyldisulfide lectin inhibitors from a dynamic combinatorial library2006Inngår i: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 22, nr 1, s. 42-48Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Carbohydrate-lectin,interactions were probed with dynamic combinatorial libraries, using the plant lectin Concanavalin A as target species. The dynamic combinatorial libraries were generated from a pool of thiol components through reversible thiol-disulfide interchange, and screened using a simple and efficient method based on a quartz crystal microbalance setup. It was found that dimers based on 1-thio- and 6-thin-mannose analogues were the most active inhibitors. Furthermore, the results clearly show that the 6-thio-mannose possess unique characteristics compared to its oxygen-containing counterpart.

  • 15.
    Pei, Zhichao
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Pei, Yuxin
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Yu, Hui
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Theurer, Matthias
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    André, Sabine
    Gabius, Hans-Joachim
    Yan, Mingdi
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Photoderivatized QCM Surfaces for the Study of Real-Time Lectin-Carbohydrate InteractionsArtikkel i tidsskrift (Fagfellevurdert)
  • 16.
    Pei, Zhichao
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Yu, Hui
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Theurer, Matthias
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Waldén, Annelie
    KTH, Skolan för bioteknologi (BIO).
    Nilsson, Peter
    KTH, Skolan för bioteknologi (BIO).
    Yan, Mingdi
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Photogenerated Carbohydrate Microarrays2007Inngår i: ChemBioChem (Print), ISSN 1439-4227, E-ISSN 1439-7633, Vol. 8, nr 2, s. 166-168Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Chemical Equation Presented) Sugars in a row. A new strategy for carbohydrate microarrays based on photochemical ligation of perfluorophenylazide-derivatized carbohydrates to PEO surfaces is presented. It constitutes a controllable and robust method of array fabrication, on the carbohydrate chemistry and on the surface-chemistry levels, and the resulting carbohydrate arrays can be efficiently used to reveal the recognition patterns of carbohydrate-binding proteins.

1 - 16 of 16
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