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  • neoglycoconjugates  (2)
  • Peptide conformation  (1)
  • catenanes  (1)
  • 1
    ISSN: 0947-6539
    Keywords: carbohydrates ; dendrimers ; glycosides ; neoglycoconjugates ; polymers ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The use of preformed poly-(propylene imine) dendrimers (DAB-dendr-(NH2)x) for the rapid and facile construction of high molecular weight carbohydrate-coated dendrimers (glyco-dendrimers) is presented. An efficient attachment of spacer-armed derivatives of D-galactose and lactose to the primary amino end groups of DAB-dendr-(NH2)x has been achieved by means of amide bond formation, using the N-hydroxysuccinimide coupling procedure. Acetate protecting groups have been employed in order to avoid side reactions at the coupling stage. Deacetylation leads to the target glycodendrimers. The reactivity of all the available DAB-dendr-(NH2)x (generations 1-5) has been investigated and a series of homologous carbohydrate-coated dendrimers have been synthesized. In addition, the attachment of larger saccharide moieties has been demonstrated by the condensation of a trisgalactoside cluster with DAB-dendr-(NH2)x carrying both four and eight primary amino groups. The regularity of the glycodendrimers has been proven by NMR spectroscopy, and the molecular weights of the low-generation carbohydrate-coated dendrimers have been determined by mass spectrometry. Modifications of DAB-dendr-(NH2)x with biologically active carbohydrates affords a new and simple approach to high molecular weight compounds that may be considered as neoglycoconjugates with perfectly symmetrical structures and that offer much promise as multivalent ligands involved in carbohydrate-protein interactions.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chicester [u.a.] : Wiley-Blackwell
    Journal of Molecular Recognition 7 (1994), S. 215-220 
    ISSN: 0952-3499
    Keywords: Intercalation ; α-helical ; Peptide conformation ; DNA ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The design and synthesis of a water-soluble 14-residue peptide, in which a quinoline intercalator is attached to the peptide backbone via alkylation of a central cysteine residue, is reported. 600 MHz 1H NMR spectroscopy and circular dichroism indicate that the peptide forms a nascent helix in aqueous solution, ie. an ensemble of turn-like structures over several adjacent residues in the peptide. A large number of sequential dNN(i, i+1) connectivities were observed in NOESY spectra, and titration of trifluoroethanol into a solution of the peptide resulted in the characteristic CD spectrum expected for an α-helix. At low DNA concentrations, CD spectroscopy indicates that this helical conformation is stabilized, presumably due to folding of the peptide in the major groove of DNA.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0947-6539
    Keywords: carbohydrates ; cluster glucosides ; convergent syntheses ; dendrimers ; neoglycoconjugates ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of carbohydratecontaining dendrimers has been achieved by a convergent growth approach. The synthetic strategy involves: 1) the synthesis of the triglucosylated derivative of tris(hydroxymethyl)methylamine (TRIS), 2) the introduction of a glycine-derived spacer and 3,3′-iminodipropionic acid derived branching units on to the TRIS derivative by amide bond formation, 3) condensation of the above saccharidecontaining dendrons with a trifunctional 1,3,5-benzenetricarbonyl derivative, used as the core, by formation of amide bonds, and 4) deprotection of the saccharide units. A 9-mer and an 18-mer, carrying nine and eighteen saccharide units at the periphery, respectively, have been synthesized, in high yields at each step, by this synthetic strategy. By a variety of chromatographic and spectroscopic techniques, the dendrimers were shown to be structurally homogeneous, monodisperse, and error-free at all steps in their growth. These investigations were complemented by molecular modeling studies on the dendrimers. The presence of slightly distorted C3 symmetry was noted in both the 9-mer and the 18-mer.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0947-6539
    Keywords: catenanes ; chirality ; enantioselection ; receptors ; self-assembly ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The design of a new class of chiral [2]catenanes is reported. The self-assembly of [2]catenanes comprising one or two 3,3′-bitolyl spacers in the π-electron-deficient component, and bis-p-phenylene-34-crown-10 (BPP 34 C 10) as the π-electron-rich component, is described. The X-ray crystal structures, together with solution-state dynamic 1H NMR spectroscopic studies, show that the degree of order characterizing the molecular structures is substantially different from that of the “parent” [2]-catenane, comprising cyclobis(paraquat-p-phenylene) and BPP34C 10. When appropriately substituted in their ortho positions, bitolyl compounds can support axial chirality: the self-assembly of axially chiral [2]catenanes, comprising one or two 3,3′-disubstituted-2,2′-dihydroxy-1,1′-binaphthyl spacers, has been achieved in good yields, showing that the introduction of the bulky, axially chiral spacer and the consequent distortion of the cavity of the π-electron-deficient component still permits good molecular recognition between the components leading to efficient catenane production. X-ray crystallography suggests that this recognition is driven by hydrogen bonding and π-π stacking interactions between the complementary subunits. The hydroxyl groups on the chiral spacer were further functionalized as benzoyl esters in a [2]catenane as well as in the tetracationic cyclophanes; that is, chemistry can be done on these catenanes. The chiral tetracationic cyclophanes exhibit good enantiomeric differentiation toward the D- and L-enantiomers of aromatic amino acids in water and their N-acetylated derivatives in organic solvents.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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