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1.
Chembiochem ; 9(7): 1100-9, 2008 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-18398881

RESUMO

Compared to monovalent carbohydrates, multivalent carbohydrate ligands exhibit significantly enhanced binding affinities to their interacting proteins. Here, we report globotriose (P(k) ligand)-functionalized gold nanoparticle (AuNP) probes for the investigation of multivalent interactions with the B(5) subunit of Shiga-like toxin I (B-Slt). Six P(k)-ligand-encapsulated AuNPs (P(k)-AuNPs) of varying particle size and linker length were synthesized and evaluated for their potential as multivalent affinity probes by using a surface plasmon resonance competition assay. The affinity of these probes for the interacting proteins was greatly affected by nanoparticle size, linker length, and ligand density on nanoparticle surface. For example, the 20-nm 20-P(k)-l-AuNP, which had a relatively long linker showed a >10(8)-fold increase in affinity compared with the mono P(k) ligand. This intrinsic high-affinity AuNP probe specifically captured the recombinant B-Slt from Escherichia coli lysate, and the resulting purity of the B-Slt was >95 %. We also developed a robust P(k)-AuNP-based detection method for Slt-I by combining the technique with silver enhancement.


Assuntos
Técnicas Biossensoriais/instrumentação , Ouro/química , Nanopartículas Metálicas/análise , Nanopartículas Metálicas/química , Toxina Shiga I/análise , Toxina Shiga I/metabolismo , Trissacarídeos/química , Bactérias/citologia , Glicoconjugados/química , Ligantes , Ligação Proteica , Toxina Shiga I/antagonistas & inibidores , Solubilidade , Ressonância de Plasmônio de Superfície , Triexosilceramidas/síntese química , Trissacarídeos/metabolismo , Água/química
2.
Org Lett ; 9(11): 2131-4, 2007 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-17477538

RESUMO

The Cu(I)-catalyzed alkyne-azide [2 + 3] cycloaddition has been demonstrated to be an effective and orthogonal conjugation reaction to covalently immobilize biomolecules on magnetic nanoparticles (MNPs). The azido group on the MNP surface provides better conjugation efficiency with alkynated molecules. Moreover, the C-terminal alkynated protein was site-specifically immobilized on MNP. The protein binding activity presented by site-specific immobilization is higher than that by random amide bond formation.

3.
Biochem Pharmacol ; 73(12): 1957-70, 2007 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-17445776

RESUMO

Alpha-galactosylceramide (alpha-GalCer), a bioactive glycolipid isolated from the marine sponge Agelas mauritianus, is a potent immunomodulator with therapeutic potential for the treatment of autoimmune diseases and cancer. The Toll-like receptor 4 (TLR4), one of the promising molecular targets for immune-modulating drugs, is commonly expressed in innate immune cells especially macrophages and dendritic cells. Currently, whether alpha-GalCer can activate TLR4 signaling pathways remains unreported. In this study, we examined the effects of alpha-GalCer and its various structural analogs, CCL-1 approximately 47, on TLR4 activation. We found that one alpha-GalCer analog (CCL-34), but not alpha-GalCer itself, strongly stimulated NF-kappaB activity in RAW 264.7 cells. CCL-34 activated NF-kappaB in a TLR4-dependent manner and stimulated TNF-alpha production in bone marrow cells of TLR4-functional C3H/HeN mice but not in those of TLR4-defective C3H/HeJ mice. Furthermore, CCL-34 treatment stimulated NF-kappaB activation and IL-8 production in a 293 cell line constitutively expressing human TLR4, MD-2 and CD14. Treatment of RAW 264.7 cells with CCL-34 also activated TLR4-downstream mitogen-activated protein kinases (ERK, JNK and p38), induced expression of TLR4-downstream genes (TNF-alpha, IL-6, IL-1beta and iNOS) and promoted production of cytokines characteristic of activated macrophages. CCL-34-treated RAW 264.7 cells acquired a distinct morphology similar to that of LPS-activated macrophages and exhibited higher phagocytotic activity. Moreover, treatment with a TLR4-neutalizing antibody inhibited the CCL-34-induced morphological alteration. In summary, we identify a novel synthetic compound CCL-34 that can activate macrophages via TLR4-dependent signaling pathways. Our results suggest that CCL-34 is an immune modulator and may serve as a potential drug lead for immunotherapy.


Assuntos
Galactosilceramidas , Ativação de Macrófagos/efeitos dos fármacos , Macrófagos Peritoneais/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Receptor 4 Toll-Like/metabolismo , Animais , Linhagem Celular , Galactosilceramidas/síntese química , Galactosilceramidas/química , Genes Reporter , Luciferases/metabolismo , Camundongos , Estrutura Molecular , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Receptor 4 Toll-Like/genética
4.
Carbohydr Res ; 341(11): 1948-53, 2006 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-16697995

RESUMO

Vanadyl triflate has been identified as a mild and efficient catalyst for the chemoselective O-isopropylidenation of functionalized carbohydrates with acetone and acetone equivalents. The current protocol is compatible with a diverse array of protecting groups and the products can be readily isolated by simple aqueous wash.


Assuntos
Acetona/química , Carboidratos/química , Mesilatos/química , Vanadatos/química , Catálise , Glicosídeos/síntese química , Glicosídeos/química , Espectroscopia de Ressonância Magnética , Estrutura Molecular
5.
Org Lett ; 7(15): 3343-6, 2005 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-16018656

RESUMO

[reaction: see text]. Aromatic aldehydes can be readily protected as acetals with 1,2- and 1,3-diols by using vanadyl triflate as a catalyst in CH(3)CN at ambient temperature. Carbohydrate-based 1,2- and 1,3-diols can similarly be protected in good to excellent yields. The catalyst can be readily recovered from the aqueous layer. In combination with vanadyl triflate-catalyzed sequential regioselective, reductive acetal opening and chemoselective acylations, the title method allows for differential functionalization of all four hydroxyl units in a given glucopyranoside.


Assuntos
Acetais/síntese química , Álcoois/química , Aldeídos/química , Técnicas de Química Combinatória , Glucosídeos/química , Água/química , Catálise , Mesilatos/química , Estrutura Molecular , Temperatura , Vanadatos/química
7.
Carbohydr Res ; 340(1): 49-57, 2005 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-15620666

RESUMO

An efficient synthesis of a Pk trisaccharide with a functionalized side arm at the reducing end for conjugation to other molecules is presented. Construction of the Pk trisaccharide with a high alpha-selectivity was achieved in high yield by coupling a reactive galactosyl phosphite donor with a lactosyl acceptor.


Assuntos
Trissacarídeos/química , Trissacarídeos/síntese química , Sequência de Carboidratos , Glicosilação , Espectroscopia de Ressonância Magnética , Dados de Sequência Molecular , Estrutura Molecular
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