Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 3 de 3
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
J Phys Chem B ; 120(33): 8193-207, 2016 08 25.
Artigo em Inglês | MEDLINE | ID: mdl-27059440

RESUMO

Brownian dynamics (BD) simulations provide here a theoretical atomic-level treatment of the reduction of human ferric cytochrome b5 (cyt b5) by NADH-cytochrome b5 reductaste (cyt b5r) and several of its mutants. BD is used to calculate the second-order rate constant of electron transfer (ET) between the proteins for direct correlation with experiments. Interestingly, the inclusion of electrostatic forces dramatically increases the reaction rate of the native proteins despite the overall negative charge of both proteins. The role played by electrostatic charge distribution in stabilizing the ET complexes and the role of mutations of several amino acid residues in stabilizing or destabilizing the complexes are analyzed. The complex with the shortest ET reaction distance (d = 6.58 Å) from rigid body BD is further subjected to 1 ns of molecular dynamics (MD) in a periodic box of TIP3P water to produce a more stable complex allowed by flexibility and with a shorter average reaction distance d = 6.02 Å. We predict a docking model in which the following ion-ion interactions are dominant (cyt b5r/cyt b5): Lys162-Heme O1D/Lys163-Asp64/Arg91-Heme O1A/Lys125-Asp70.


Assuntos
Citocromo-B(5) Redutase/química , Citocromos b5/química , Elétrons , Flavina-Adenina Dinucleotídeo/química , Heme/química , NAD/química , Substituição de Aminoácidos , Sítios de Ligação , Citocromo-B(5) Redutase/metabolismo , Citocromos b5/metabolismo , Transporte de Elétrons , Flavina-Adenina Dinucleotídeo/metabolismo , Heme/metabolismo , Humanos , Cinética , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Mutação , NAD/metabolismo , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , Estrutura Secundária de Proteína , Eletricidade Estática , Termodinâmica
2.
FEBS J ; 280(9): 2056-67, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23480609

RESUMO

Burkholderia oklahomensis EO147 agglutinin (BOA) is a 29 kDa member of the Oscillatoria agardhii agglutinin (OAA) family of lectins. Members of the OAA family recognize high-mannose glycans, and, by binding to the HIV envelope glycoprotein 120 (gp120), block the virus from binding to and entering the host cell, thereby inhibiting infection. OAA-family lectins comprise either one or two homologous domains, with a single domain possessing two glycan binding sites. We solved the structure of BOA in the ligand-free form as well as in complex with four molecules of 3α,6α-mannopentaose, the core unit of the N-linked high-mannose structures found on gp120 in vivo. This is the first structure of a double-domain OAA-family lectin in which all four binding sites are occupied by ligand. The structural details of the BOA-glycan interactions presented here, together with determination of affinity constants and HIV inactivation data, shed further light onto the structure-function relationship in this important class of anti-HIV proteins.


Assuntos
Aglutininas/química , Fármacos Anti-HIV/química , Proteínas de Bactérias/química , Burkholderia , Lectinas de Ligação a Manose/química , Aglutininas/farmacologia , Sequência de Aminoácidos , Fármacos Anti-HIV/farmacologia , Proteínas de Bactérias/farmacologia , Sítios de Ligação , Configuração de Carboidratos , Sequência de Carboidratos , Linhagem Celular , Sequência Conservada , Cristalografia por Raios X , HIV-1/efeitos dos fármacos , HIV-1/fisiologia , Humanos , Ligação de Hidrogênio , Concentração Inibidora 50 , Mananas/química , Lectinas de Ligação a Manose/farmacologia , Modelos Moleculares , Dados de Sequência Molecular , Ressonância Magnética Nuclear Biomolecular , Ligação Proteica , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína
3.
J Biol Chem ; 287(40): 33796-811, 2012 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-22865886

RESUMO

Oscillatoria agardhii agglutinin homolog (OAAH) proteins belong to a recently discovered lectin family. All members contain a sequence repeat of ~66 amino acids, with the number of repeats varying among different family members. Apart from data for the founding member OAA, neither three-dimensional structures, information about carbohydrate binding specificities, nor antiviral activity data have been available up to now for any other members of the OAAH family. To elucidate the structural basis for the antiviral mechanism of OAAHs, we determined the crystal structures of Pseudomonas fluorescens and Myxococcus xanthus lectins. Both proteins exhibit the same fold, resembling the founding family member, OAA, with minor differences in loop conformations. Carbohydrate binding studies by NMR and x-ray structures of glycan-lectin complexes reveal that the number of sugar binding sites corresponds to the number of sequence repeats in each protein. As for OAA, tight and specific binding to α3,α6-mannopentaose was observed. All the OAAH proteins described here exhibit potent anti-HIV activity at comparable levels. Altogether, our results provide structural details of the protein-carbohydrate interaction for this novel lectin family and insights into the molecular basis of their HIV inactivation properties.


Assuntos
Aglutininas/química , Fármacos Anti-HIV/química , Lectinas/química , Oscillatoria/metabolismo , Sequência de Aminoácidos , Carboidratos/química , Cristalografia por Raios X/métodos , HIV/metabolismo , Espectroscopia de Ressonância Magnética/métodos , Conformação Molecular , Dados de Sequência Molecular , Polissacarídeos/química , Ligação Proteica , Conformação Proteica , Estrutura Secundária de Proteína , Proteínas/química , Homologia de Sequência de Aminoácidos , Difração de Raios X
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...