RESUMO
The convergent preparation of Janus molecular nanoparticles by thiourea-"clicking" of α,α'-trehalose halves has been implemented; the strategy allows access to macrocyclic derivatives with seggregated cationic and lipophilic domains that in the presence of DNA undergo pH-dependent self-assembly into lamellar superstructures, as established by electrochemical, structural (SAXS), microscopical (TEM) and computational techniques, that mediate transfection in vitro and in vivo.
Assuntos
Química Click/métodos , DNA/química , Nanopartículas/química , Oligossacarídeos/química , Trealose/química , Animais , Células COS , Chlorocebus aethiops , DNA/metabolismo , Concentração de Íons de Hidrogênio , Nanopartículas/metabolismo , Oligossacarídeos/metabolismo , Espalhamento a Baixo Ângulo , Trealose/metabolismo , Difração de Raios XRESUMO
The binding properties of a spacer-linked synthetic Sd(a) tetrasaccharide beta-D-GalpNAc-(1-->4)-alpha-Neu5Ac-(2-->3)]-beta-D-Galp-(1-->4)-beta-D-GlcpNAc-(1-->O)-(CH(2))(5)-NH(2) (1), two tetrasaccharide mimics beta-D-Galp-(1-->4)-alpha-Neu5Ac-(2-->3)]-beta-D-Galp-(1-->4)-beta-D-GlcpNAc-(1-->O)-(CH(2))(5)-NH(2) (2) and beta-D-GlcpNAc-(1-->4)-alpha-Neu5Ac-(2-->3)]-beta-D-Galp-(1-->4)-beta-D-GlcpNAc-(1-->O)-(CH(2))(5)-NH(2) (3), and two trisaccharide mimics beta-D-GalpNAc-(1-->4)-3-O-(SO(3)H)-beta-D-Galp-(1-->4)-beta-D-GlcpNAc-(1-->O)-(CH(2))(5)-NH(2) (4) and beta-D-GalpNAc-(1-->4)-3-O-(CH(2)COOH)-beta-D-Galp-(1-->4)-beta-D-GlcpNAc-(1-->O)-(CH(2))(5)-NH(2) (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 Sd(a) determinant.
Assuntos
Lectinas/química , Oligossacarídeos/química , Ressonância de Plasmônio de Superfície/métodos , Trissacarídeos/síntese química , Sequência de Carboidratos , Antígenos de Histocompatibilidade/química , Cinética , Modelos Biológicos , Lectinas de Plantas , Plantas , Trissacarídeos/químicaRESUMO
The binding properties of multitopic sugar thiourea receptors toward dicarboxylate and monosaccharide guests have been examined taking glutarate and octyl beta-D-glucopyranoside as model ligands. For the anionic hydrogen bond acceptor, both the complex stoichiometry and the association constants (K(as)) were found to be strongly dependent on the relative disposition of recognition elements in the host. In contrast, for the glucoside guest a 1:1 stoichiometry was observed in all cases, the K(as) values being largely independent of the unbound state provided that geometrically equivalent supramolecular topologies can be achieved.
Assuntos
Metabolismo dos Carboidratos , Ácidos Dicarboxílicos/metabolismo , Monossacarídeos/metabolismo , Receptores de Superfície Celular/metabolismo , Tioureia/metabolismo , Sítios de Ligação , Ligação de Hidrogênio , Espectroscopia de Ressonância Magnética , Receptores de Superfície Celular/química , Espectrometria de Massas de Bombardeamento Rápido de ÁtomosRESUMO
The conformational behaviour of the spacer-linked synthetic Sd(a) tetrasaccharide beta-D-GalpNAc-(1-->4)-[alpha-Neu5Ac-(2-->3)]-beta-D-Galp-(1-->4)- beta-D-GlcpNAc-(1-->O)(CH2)5NH2 (1) and the two mimics beta-D-Galp-(1-->4)-[alpha-Neu5Ac-(2-->3)]-beta-D-Galp-(1-->4)-bet a-D-GlcpNAc-(1-->O)(CH2)5NH2 (2) and beta-D-GlcpNAc-(1-->4)-[alpha-Neu5Ac-(2-->3)]-beta-D-Galp-(1-->4)- beta-D-GlcpNAc-(1-->O)(CH2)5NH2 (3) were investigated by 1H NMR spectroscopy in combination with molecular dynamics (MD) simulations in water. Experimental 2D 1H ROESY cross-peak intensities (ROEs) of the tetrasaccharides were compared with calculated ROEs derived from MD trajectories using the CROSREL program. Analysis of these data indicated that the oligosaccharidic skeletons of the compounds 1-3 are rather rigid, especially the beta-D-Hex(NAc)-(1-->4)-[alpha-Neu5Ac-(2-->3)]-beta-D-Galp fragments. The alpha-Neu5-Ac-(2-->3)-beta-D-Galp linkage occurred in two different energy minima in the three-dimensional structure of the compounds 1-3 in aqueous solution. Experimental data and dynamics simulations supported the finding that the higher energy rotamer (CHEAT forcefield) was abundant in compounds 1 and 3 due to the existence of a hydrogen bond between the carboxyl group of the sialic acid and the acetamido group of the terminal monosaccharide (GalNAc or GlcNAc) unit. The conformational similarity between 1 and 3 leads to the suggestion that also their activities will be alike.
Assuntos
Antígenos HLA/química , Oligossacarídeos/química , Configuração de Carboidratos , Sequência de Carboidratos , Carbono/química , Simulação por Computador , Modelos Moleculares , Dados de Sequência Molecular , Ressonância Magnética Nuclear Biomolecular/métodos , Prótons , Soluções , ÁguaRESUMO
6,6'-Dideoxy-6,6'-diisothiocyanato-alpha,alpha'-trehalose (4), 6-deoxy-6-isothiocyanato-alpha-D-fructo-furanose beta-D-fructopyranose 1,2':2,1'-dianhydride (11), 6,6'-dideoxy-6,6'-diisothiocyanatosucrose (16), and per(6-deoxy-6-isothiocyanato)-cyclomaltohexaose (23), -cyclomaltoheptaose (27), and -cyclomaltooctaose (31) have been prepared in high yield by reaction of the corresponding amino sugars with thiophosgene. In the absence of base, all isothiocyanates were stable and could be stored and acetylated without decomposition. In the presence of triethylamine, 6,6'-dideoxy-6,6'-diisothiocyanato-alpha,alpha'-trehalose underwent intramolecular cyclisation involving HO-4 to give the corresponding bis(cyclic thiocarbamate). The product of cyclisation at a single glucopyranosyl unit was obtained in the treatment of the above diisothiocyanate with mixed (H+, HO-) ion-exchange resin. Under identical reaction conditions, 6,6'-dideoxy-6,6'-diisothiocyanatosucrose yielded exclusively the product of intramolecular cyclisation at the D-glucopyranosyl moiety, while derivatives of alpha-D-fructofuranose beta-D-fructopyranose 1,2':2,1'-dianhydride and cyclomaltooligosaccharides remained unchanged.