RESUMO
The Bauhinia ungulata, also known by its common name "pata de vaca", is one of the species used in Brazil for medicinal purposes, and is commonly used for the treatment of diabetes. In this study, the authors studied the interaction between the chemical constituents which are present in the essential oil of Bauhinia ungulata (EOBU), collected in Boa Vista-RR, Legal Amazon, and their effects on the enzyme acetylcholinesterase (AChE) in the essential oil. The analysis that we perform includes proton magnetic resonance ( 1H NMR), enzymatic inhibition, molecular docking, in silico toxicity prediction, enrichment analysis, and target prediction for biological interactions. According to the tests performed on the essential oil, it obtained 100% inhibition of the enzyme AChE. During 1H NMR experiments, it was found that α- Bisabolol, one of the main components, had a significant alteration in its chemical shift. A molecular docking analysis confirmed that this compound binds to the AChE enzyme, which confirms the 1H NMR analysis. The results of this work showed that the major component of EOBU acted as a possible inhibitor of AChE enzyme in vitro and in silico assays. These results show that EOBU could be potentially applied in Alzheimer's disease treatment.
Assuntos
Acetilcolinesterase , Bauhinia , Inibidores da Colinesterase , Simulação de Acoplamento Molecular , Óleos Voláteis , Inibidores da Colinesterase/farmacologia , Inibidores da Colinesterase/química , Bauhinia/química , Brasil , Acetilcolinesterase/metabolismo , Óleos Voláteis/química , Óleos Voláteis/farmacologia , Simulação por Computador , Sesquiterpenos/farmacologia , Sesquiterpenos/isolamento & purificação , Sesquiterpenos/químicaRESUMO
The plant popularly known as "negramina" (Siparuna guianensis Aubl.), member of the family Siparunaceae produces an essential oil that presents several biological activities reported in literature. Here, the essential oil was obtained by hydrodistillation from fresh leaves collected in the state of Roraima, far north of the Amazon. Chemical composition of the essential oil was characterized by gas chromatography coupled to mass spectrometry (GC-MS) and flame ionization detector (GC-FID). The sesquiterpenoid shyobunone and its derivatives were identified as major compounds in the oil (>40%). The effect of S. guianensis essential oil on the acetylcholinesterase (AChE) activity from Crassostrea rhizophorae, Litopenaeus vannamei and Electrophorus electricus was tested by spectrophotometric assays. The essential oil has been identified as an AChE inhibitor. The mechanism of inhibition was investigated as well as spectrofluorimetric interactions between the essential oil and the enzyme. 1H NMR titration and molecular docking were also investigated. The spectrophotometric results revealed that shyobunone and its derivatives strongly interact with AChE with a kind of non-competitive inhibition. Interaction studies support the results of enzyme inhibition. Molecular coupling predicted that iso-shyobunone is the strongest ligand, corroborated by fluorescence suppression and 1H NMR titration results. In conclusion, Siparuna guianensis essential oil can be a new source of shyobunone and derivatives capable to reversibly inhibit AChE showing potential neuroprotective properties to be applied in the treatment of Alzheimer's disease.
Assuntos
Óleos Voláteis , Sesquiterpenos , Cromatografia Gasosa-Espectrometria de Massas , Simulação de Acoplamento Molecular , Óleos Voláteis/farmacologia , Folhas de Planta , Sesquiterpenos/farmacologiaRESUMO
The ability of erythrocytes, infected by Plasmodium falciparum, to adhere to endothelial cells (cytoadherence) and to capture uninfected erythrocyte (rosetting) is the leading cause of death by severe malaria. Evidences link the binding of the adhesin Duffy Binding Like1-α (DBL1α) domain to the ABH histo-blood antigens with formation of rosettes. Inspired by this very close relationship between the disease susceptibility and individual blood type, here we investigate the structural requirements involved in the interaction of DBL1α with A, B and H histo-blood determinants and their subtypes. Our results evidence the high preference of DBL1α to A epitopes, in comparison to B and H epitopes. DBL1α interacts with ABH epitopes in subtype specific manner, presenting a remarkable affinity for type 2 structures, Fucα1-2Galß1-4GlcNAcß1, particularly the A2 epitope. The contacts made by DBL1α binding pocket and the ABH histo-blood groups were mapped by theoretical methods and supported by NMR experiments.
RESUMO
The reaction between cucurbit[6]uril (CB[6]) and lanthanide chlorides (Eu, Sm, Tb and Tm) in acidic aqueous media led to four new structures. The compounds obtained are isostructural with general formula [Ln2(H2O)12(H2O@CB[6])]Cl6(H2O)4 (Ln = Eu(3+) (1), Sm(3+) (2), Tb(3+) (3) and Tm(3+) (4)) and crystallize in the P21/c space group. For the complexes with Eu(3+), Sm(3+) and Tb(3+), the luminescent properties in the solid state and aqueous media were explored and all spectroscopic observations are in excellent agreement with the single crystal structure data. The excitation and emission spectra show the typical f-f transitions characteristic of the trivalent lanthanide ions. The transitions (7)FJ â (5)D1 (J = 0,1,2) in the europium compound and (7)FJ â (5)D4 (J = 0,1,2) in the terbium compound, not yet reported in lanthanide-CB[n] compounds, were also observed.
RESUMO
Trypanosoma cruzi trans-sialidase (TcTS) is a key target protein for Chagas disease chemotherapy. In this study, we investigated the implications of active site flexibility on the biochemical mechanism of TcTS. Molecular dynamics studies revealed remarkable plasticity in the TcTS catalytic site, demonstrating, for the first time, how donor substrate engagement with the enzyme induces an acceptor binding site in the catalytic pocket that was not previously captured in crystal structures. Furthermore, NMR data showed cooperative binding between donor and acceptor substrates, supporting theoretical results. In summary, our data put forward a coherent dynamic framework to understand how a glycosidase evolved its highly efficient trans-glycosidase activity.
Assuntos
Evolução Molecular , Simulação de Dinâmica Molecular , Proteínas de Protozoários/química , Trypanosoma cruzi/enzimologia , Catálise , Domínio Catalítico , Glicoproteínas , Neuraminidase , Ressonância Magnética Nuclear Biomolecular , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo , Trypanosoma cruzi/genéticaRESUMO
Cytoskeleton and protein trafficking processes, including vesicle transport to synapses, are key processes in neuronal differentiation and axon outgrowth. The human protein FEZ1 (fasciculation and elongation protein zeta 1 / UNC-76, in C. elegans), SCOCO (short coiled-coil protein / UNC-69) and kinesins (e.g. kinesin heavy chain / UNC116) are involved in these processes. Exploiting the feature of FEZ1 protein as a bivalent adapter of transport mediated by kinesins and FEZ1 protein interaction with SCOCO (proteins involved in the same path of axonal growth), we investigated the structural aspects of intermolecular interactions involved in this complex formation by NMR (Nuclear Magnetic Resonance), cross-linking coupled with mass spectrometry (MS), SAXS (Small Angle X-ray Scattering) and molecular modelling. The topology of homodimerization was accessed through NMR (Nuclear Magnetic Resonance) studies of the region involved in this process, corresponding to FEZ1 (92-194). Through studies involving the protein in its monomeric configuration (reduced) and dimeric state, we propose that homodimerization occurs with FEZ1 chains oriented in an anti-parallel topology. We demonstrate that the interaction interface of FEZ1 and SCOCO defined by MS and computational modelling is in accordance with that previously demonstrated for UNC-76 and UNC-69. SAXS and literature data support a heterotetrameric complex model. These data provide details about the interaction interfaces probably involved in the transport machinery assembly and open perspectives to understand and interfere in this assembly and its involvement in neuronal differentiation and axon outgrowth.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas de Transporte/metabolismo , Proteínas de Membrana/metabolismo , Proteínas Associadas aos Microtúbulos/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/química , Proteínas Adaptadoras de Transdução de Sinal/genética , Sequência de Aminoácidos , Sítios de Ligação/genética , Transporte Biológico , Proteínas de Transporte/química , Proteínas de Transporte/genética , Humanos , Cinesinas , Espectroscopia de Ressonância Magnética , Proteínas de Membrana/química , Proteínas de Membrana/genética , Modelos Moleculares , Dados de Sequência Molecular , Proteínas do Tecido Nervoso/química , Proteínas do Tecido Nervoso/genética , Ligação Proteica , Multimerização Proteica , Estrutura Terciária de Proteína , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Espalhamento a Baixo Ângulo , Homologia de Sequência de Aminoácidos , Técnicas do Sistema de Duplo-Híbrido , Difração de Raios XRESUMO
The glycobiology of the cestodes, a class of parasitic flatworms, is still largely unexplored. An important cestode species is Echinococcus granulosus, the tissue-dwelling larval stage of which causes hydatid disease. The E. granulosus larva is protected from the host by a massive mucin-based extracellular matrix termed laminated layer (LL). We previously reported ( Díaz et al. 2009. Biochemistry 48:11678-11691) the molecular structure of the most abundant LL O-glycans, comprising up to six monosaccharide residues. These are based on Cores 1 and 2, in cases elongated by a chain of Galpß1-3 residues, which can be capped by Galpα1-4. In addition, the Core 2 GlcNAcp residue can be decorated with the Galpα1-4Galpß1-4 disaccharide. Larger glycans also detected contained additional HexNAc residues that could not be explained by the structural repertoire described above. In this work, we elucidate, by mass spectrometry (MS) and nuclear magnetic resonance (NMR), six additional glycans from the E. granulosus LL between six and eight residues in size. Their structures are related to those already described but in cases bear GlcNAcpß1-6 or Galpα1-4Galpß1-4GlcNAcpß1-6 as ramifications on the core Galpß1-3 residue. We also obtained evidence that noncore Galpß1-3 residues can be similarly ramified. Thus, the new motif together with the previous information may explain all the glycan compositions detected in the LL by MS. In addition, we show that the anti-Echinococcus monoclonal antibody E492 (Parasite Immunol 21:141, 1999) recognizes Galpα1-4Galpß1-4GlcNAcp (the blood P(1)-antigen motif). This explains the antibody's reactivity with a range of Echinococcus tissues, as the P(1)-motif is also carried on non-LL N-glycans and glycolipids from this genus.
Assuntos
Echinococcus granulosus/química , Polissacarídeos/química , Animais , Configuração de Carboidratos , Globosídeos/imunologia , Monossacarídeos/química , Polissacarídeos/imunologiaRESUMO
Cellulases participate in a number of biological events, such as plant cell wall remodelling, nematode parasitism and microbial carbon uptake. Their ability to depolymerize crystalline cellulose is of great biotechnological interest for environmentally compatible production of fuels from lignocellulosic biomass. However, industrial use of cellulases is somewhat limited by both their low catalytic efficiency and stability. In the present study, we conducted a detailed functional and structural characterization of the thermostable BsCel5A (Bacillus subtilis cellulase 5A), which consists of a GH5 (glycoside hydrolase 5) catalytic domain fused to a CBM3 (family 3 carbohydrate-binding module). NMR structural analysis revealed that the Bacillus CBM3 represents a new subfamily, which lacks the classical calcium-binding motif, and variations in NMR frequencies in the presence of cellopentaose showed the importance of polar residues in the carbohydrate interaction. Together with the catalytic domain, the CBM3 forms a large planar surface for cellulose recognition, which conducts the substrate in a proper conformation to the active site and increases enzymatic efficiency. Notably, the manganese ion was demonstrated to have a hyper-stabilizing effect on BsCel5A, and by using deletion constructs and X-ray crystallography we determined that this effect maps to a negatively charged motif located at the opposite face of the catalytic site.