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1.
Biophys Chem ; 256: 106270, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31706136

RESUMO

DNA strands can be designed to assemble into stable three-dimensional structures, based on Watson-Crick base pairing rules. The simplest of these is the DNA tetrahedron that is composed of four oligonucleotides. We have re-designed the sequence of a DNA tetrahedron so that it contains a single (AATT) binding site for the minor groove binding ligand Hoechst 33258. We examined the stability of this structure by placing fluorescent groups within each of its edges and have shown that all the edges melt at the same temperature in the absence of the ligand. The minor groove ligand still binds to its recognition sequence within the tetrahedron and increases the melting temperature of the folded complex. This ligand-induced stabilisation is propagated into the adjacent helical arms and the tetrahedron melts as a single entity in a cooperative fashion.


Assuntos
DNA/química , Ligantes , Sequência de Bases , Sítios de Ligação , Bisbenzimidazol/química , Bisbenzimidazol/metabolismo , Conformação de Ácido Nucleico , Transição de Fase/efeitos da radiação , Espectrometria de Fluorescência , Temperatura de Transição , Raios Ultravioleta
2.
Biophys Chem ; 256: 106281, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31756663

RESUMO

Timely and accurate diagnosis of Alzheimer's disease (AD) remains a major challenge in the medical arena. ß-amyloid (Aß) imaging techniques such as positron emission tomography and single photon emission computed tomography require the use of an imaging probe. To date, only flutemetamol, florbetaben and florbetapir have been approved for clinical use as imaging probes. Design of imaging probes requires a detailed understanding of disease mechanism(s) and receptor-ligand interaction. In this study, molecular docking, molecular dynamics and binding free energies were used to investigate the multiple binding sites exhibited by ß-amyloid fibrils. Protein atomic models 2BEG, 5KK3, 2M4J, 2LMN, 5OQV, 2NAO, 2MVX and 2MXU (protein databank codes) were used to investigate the nature and location of binding sites and binding profiles of selected molecules with known affinities. Although amyloid fibrils are known to have multiple binding sites, we demonstrated that model 2MXU possesses one site which is druggable and can bind with common scaffolds currently being used in the imaging of amyloid fibrils. Models 2NAO, 5KK3 and 2M4J revealed that even though multiple sites may be available in some fibrils, the entire protein may not have a druggable site. Molecular dynamics revealed atomic models 2MXU and 2MVX to be the least flexible among the list. The outcomes of this investigation can be translated to assist in designing novel molecules that can be used for brain imaging in Alzheimer's disease.


Assuntos
Amiloide/química , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Amiloide/metabolismo , Sítios de Ligação , Bases de Dados de Proteínas , Humanos , Ligantes , Ligação Proteica , Estrutura Terciária de Proteína
3.
Biophys Chem ; 257: 106315, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31841862

RESUMO

Lipocalins are a widely distributed family of extracellular proteins typically involved in the transport of small hydrophobic molecules. To gain new insights into the molecular basis that governs ligand recognition by this ancient protein family, the binding properties of the domain-swapped dimer bovine odorant binding protein (bOBP) and its monomeric mutant bOBP121G+ were characterized using calorimetric techniques and molecular dynamics simulations. Thermal unfolding profiles revealed that the isolated bOBP subunits behave as a cooperative folding unit. In addition, bOBP and bOBP121G+ exhibited similar ligand binding properties, characterized by a non-classical hydrophobic effect signature. The energetic differences in the binding of bOBP to 1-hexen-3-ol and the physiological ligand 1-octen-3-ol were strikingly larger than those observed for the interaction of other lipocalins with congeneric ligands. MD simulations revealed that the recurrent opening of transient pores in the submicrosecond timescale allows a profuse exchange of water molecules between the protein interior and the surrounding solvent. This picture contrasts with other lipocalins whose ligand-free binding cavities are devoid of solvent molecules. Furthermore, the simulations indicated that internal water molecules solvate the protein cavity suboptimally, forming fewer hydrogen bonds and having lower density and higher potential energy than bulk water molecules. Upon ligand occupation, water molecules were displaced from the binding cavity in an amount that depended on the ligand size. Taken together, calorimetric and MD-simulation results are consistent with a significant contribution of cavity desolvation to the enthalpically-driven interaction of bOBP with its hydrophobic ligands.


Assuntos
Ligantes , Receptores Odorantes/química , Solventes/química , Animais , Sítios de Ligação , Bovinos , Interações Hidrofóbicas e Hidrofílicas , Simulação de Dinâmica Molecular , Mutagênese Sítio-Dirigida , Estabilidade Proteica , Receptores Odorantes/genética , Receptores Odorantes/metabolismo , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/química , Proteínas Recombinantes/isolamento & purificação , Termodinâmica , Água/química
4.
Zhongguo Zhong Yao Za Zhi ; 44(19): 4152-4157, 2019 Oct.
Artigo em Chinês | MEDLINE | ID: mdl-31872692

RESUMO

Target discovery is the core of elucidating the mechanism of traditional Chinese medicine( TCM),and it is also the key to correlate the chemical composition and pharmacological action of TCM. The traditional target screening methods such as the activitybased probe profiling,affinity chromatography,and protein microarray are commonly used in the past,however,which are limited in TCM due to the complexity of small molecules existed in the herbal medicine. The label-free small molecule probe is a recently well-applied technology in the target discovery of natural products,which is characterized by discovering the small molecule-protein ligation without any structural modification at the ligands,and is therefore suitable to the complex chemical constituents in TCM. Furthermore,this method is conducted on the basis of proteome,which is advanced in the discovery of new or multiple target proteins of TCM. Owing to the potential of label-free probe in the target discovery of TCM,its analytical principle,application status,and general protocol were reviewed in this paper. The label-free probe technology is anticipated to accelerate the mechanism-uncovering of TCM.


Assuntos
Medicamentos de Ervas Chinesas , Medicina Tradicional Chinesa , Plantas Medicinais , Ligantes , Fitoterapia
5.
Yi Chuan ; 41(11): 1041-1049, 2019 Nov 20.
Artigo em Chinês | MEDLINE | ID: mdl-31735706

RESUMO

Accurate epitope presentation prediction is a key procedure in tumour immunotherapies based on neoantigen for targeting T cell specific epitopes. Epitopes identified by mass spectrometry (MS) is valuable to train an epitope presentation prediction model. In spite of the accelerating accumulation of MS data, the number of epitopes that match most of human leukocyte antigens (HLAs) is relatively small, which makes it difficult to build a reliable prediction model. Therefore, this research attempted to use the transfer learning method to train a model to learn common features among the mixed allele specific epitopes. Then based on this pre-trained model, we used the allele-specific epitopes to train the final epitope presentation prediction model, termed Pluto. The average 0.1% positive predictive value (PPV) of Pluto outperformed the prediction model without pretraining with a margin of 0.078 on the same validation dataset. When evaluating Pluto on external HLA eluted ligand datasets, Pluto achieved an averaged 0.1% PPV of 0.4255, which is better than the prediction model without pretraining (0.3824) and other popular methods, including MixMHCpred (0.3369), NetMHCpan4.0-EL (0.4000), NetMHCpan4.0-BA (0.3188) and MHCflurry (0.3002). Moreover, when it comes to the evaluation of predicting immunogenicity, Pluto can identify more neoantigens than other tools. Pluto is publicly available at https://github.com/weipenegHU/Pluto.


Assuntos
Algoritmos , Apresentação do Antígeno , Epitopos de Linfócito T/química , Animais , Humanos , Ligantes , Aprendizado de Máquina
6.
J Phys Chem Lett ; 10(22): 7270-7276, 2019 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-31692352

RESUMO

M2 muscarinic acetylcholine receptor (M2R) is a prototypical G protein-coupled receptor (GPCR) that responds to acetylcholine and mediates various cellular responses in the nervous system. Here, we used attenuated total reflection-Fourier transform infrared spectroscopy analyses on M2R reconstituted in a lipid membrane to understand the molecular mechanism behind the ligand binding-induced conformational changes. Upon agonist binding, M2R shows large spectral change of the amide-I band corresponding to backbone C═O stretch, which likely connects with the receptor activation in the lipid environment. These results pave the way to probe effects of different ligand binding on GPCRs using vibrational spectroscopy.


Assuntos
Receptor Muscarínico M2/química , Sítios de Ligação , Humanos , Ligantes , Conformação Proteica , Espectroscopia de Infravermelho com Transformada de Fourier
8.
Adv Exp Med Biol ; 1163: 171-186, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31707704

RESUMO

NMR allows assessment of protein structure in solution. Unlike conventional X-ray crystallography that provides snapshots of protein conformations, all conformational states are simultaneously accessible to analysis by NMR. This is a significant advantage for discovery and characterization of allosteric effects. These effects are observed when binding at one site of the protein affects another distinct site through conformational transitions. Allosteric regulation of proteins has been observed in multiple physiological processes in health and disease, providing an opportunity for the development of allosteric inhibitors. These compounds do not directly interact with the orthosteric site of the protein but influence its structure and function. In this book chapter, we provide an overview on how NMR methods are utilized to identify allosteric sites and to discover novel inhibitors, highlighting examples from the field. We also describe how NMR has contributed to understanding of allosteric mechanisms and propose that it is likely to play an important role in clarification and further development of key concepts of allostery.


Assuntos
Sítio Alostérico , Descoberta de Drogas , Ligantes , Espectroscopia de Ressonância Magnética , Regulação Alostérica , Sítios de Ligação , Descoberta de Drogas/métodos , Descoberta de Drogas/tendências , Conformação Proteica
9.
Adv Exp Med Biol ; 1163: 225-251, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31707706

RESUMO

G protein-coupled receptors (GPCRs) influence virtually every aspect of human physiology; about one-third of all marketed drugs target members of this family. GPCR allosteric ligands hold the promise of improved subtype selectivity, spatiotemporal sensitivity, and possible biased property over typical orthosteric ligands. However, only a small number of GPCR allosteric ligands have been approved as drugs or in clinical trials since the discovery process is very challenging. The rapid development of GPCR structural biology leads to the discovery of several allosteric sites and sheds light on understanding the mechanism of GPCR allosteric ligands, which is critical for discovering novel therapeutics. This book chapter summarized different GPCR allosteric modulating mechanisms and discussed validated mechanisms based on allosteric modulator-GPCR complex structures.


Assuntos
Descoberta de Drogas , Receptores Acoplados a Proteínas-G , Regulação Alostérica , Sítio Alostérico , Humanos , Ligantes , Relação Estrutura-Atividade
10.
Adv Exp Med Biol ; 1163: 313-334, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31707709

RESUMO

Protein-protein interactions (PPIs) represent promising drug targets of broad-spectrum therapeutic interests due to their critical implications in both health and disease circumstances. Hence, they are widely accepted as the Holy Grail of drug development. Historically, PPIs were rendered "undruggable" for their large, flat, and pocket-less structures. Current attempts to drug these "intractable" targets include orthosteric and allosteric methodologies. Previous efforts employing orthosteric approaches like protein therapeutics and orthosteric small molecules frequently suffered from poor performance caused by the difficulties in directly targeting PPI interfaces. As structural biology progresses rapidly, allosteric modulators, which direct to the allosteric regulatory sites remote to the PPI surfaces, have gradually established as a potential solution. Allosteric pockets are topologically distal from the PPI orthosteric sites, and their ligands do not need to compete with the PPI partners, which helps to improve the physiochemical and pharmacological properties of allosteric PPI modulators. Thus, exploiting allostery to tailor PPIs is regarded as a tempting strategy in future PPI drug discovery. Here, we provide a comprehensive review of our representative achievements along the way we utilize allosteric effects to tame the difficult PPI systems into druggable targets. Importantly, we provide an in-depth mechanistic analysis of this success, which will be instructive to future related lead optimizations and drug design. Finally, we discuss the current challenges in allosteric PPI drug discovery. Their solutions as well as future perspectives are also presented.


Assuntos
Sítio Alostérico , Descoberta de Drogas , Regulação Alostérica , Sítio Alostérico/fisiologia , Ligantes , Ligação Proteica/efeitos dos fármacos , Inibidores de Proteínas Quinases/farmacologia
11.
J Biomed Nanotechnol ; 15(12): 2413-2427, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31748021

RESUMO

With aging of population, changing of living habits, and intake of high-fat diet, more and more people have been suffering from cardio-cerebral apoplexy. The synchronous treatment of cardio-cerebral conditions based on an integral strategy may bring benefit to the better clinical efficacy. The simultaneously-targeting delivery of active molecules by nanoscale carriers to heart and brain remains unmet problem. The physiological difference of targets between heart and brain makes it a huge challenge which one targeting ligand modification acquires the delivery of two organs and treatment, simultaneously. Traditionally, dually targeting strategies are introduced to enhance the selectivity for one aimed tissue and delivery efficiency of these particles. However, the interference between two targeting ligands on the surface of nanoscale carriers may influence the affinity of these ligands with their receptors or transporters, resulting to the change distribution of carriers. Herein, we observed that how anti-cardiac troponin I (cTnI) antibody (Ab) conjugated with the linker, polyethylene glycol (PEG), on the surface of liposomes influenced the affinity of mannose derivatives with transporter and regulated distribution of these vesicles in the heart and brain. The dually targeting liposomes can target to the heart and brain tissue simultaneously by the regulation length of PEG chain linking with p -pentanoic acid phenyl-α-D-acetylmannosamine (Ac4MAN). These results may bring benefit to design the multi-modification of nanocarriers and the treatment of cardio-cerebral diseases.


Assuntos
Lipossomos , Portadores de Fármacos , Sistemas de Liberação de Medicamentos , Imunoconjugados , Ligantes , Manose , Polietilenoglicóis
12.
Phys Chem Chem Phys ; 21(42): 23501-23513, 2019 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-31617551

RESUMO

YIV-906 (formally PHY906, KD018) is a four-herb formulation that is currently being developed to improve the therapeutic index and ameliorate the side effects of many chemotherapeutic drugs including sorafenib, irinotecan, and capecitabine. However, as a promising anti-cancer adjuvant, the molecular mechanism of action of YIV-906 remains unrevealed due to its multi-component and multi-target features. Since YIV-906 has been shown to induce apoptosis and autophagy in cancer cells through modulating the negative regulators of ERK1/2, namely DUSPs, it is of great interest to elucidate the key components that cause the therapeutic effect of YIV-906. In this work, we investigated the mechanism of YIV-906 inhibiting DUSPs, using a broad spectrum of molecular modelling techniques, including molecular docking, molecular dynamics (MD) simulations, and binding free energy calculations. In total, MD simulations and binding free energy calculations were performed for 99 DUSP-ligand complexes. We found that some herbal components or their metabolites could inhibit DUSPs. Based on the docking scores and binding free energies, the sulfation and glucuronidation metabolites of the S ingredient in YIV-906 play a leading role in inhibiting DUSPs, although several original herbal chemicals with carboxyl groups from the P and Z ingredients also make contributions to this inhibitory effect. It is not a surprise that the electrostatic interaction plays the dominant role in the ligand binding process, given the fact that several charged residues reside in the binding pockets of DUSPs. Our MD simulation results demonstrate that the sulfate moieties and carboxyl moieties of the advantageous ligands from YIV-906 can occupy the enzymes' catalytic sites, mimicking the endogenous phosphate substrates of DUSPs. As such, the ligand binding can inhibit the association of DUSPs and ERK1/2, which in turn reduces the dephosphorylation of ERK1/2 and causes cell cycle arrest in the tumor. Our modelling study provides useful insights into the rational design of highly potent anti-cancer drugs targeting DUSPs. Finally, we have demonstrated that multi-scale molecular modelling techniques are able to elucidate molecular mechanisms involving complex molecular systems.


Assuntos
Antineoplásicos Fitogênicos/química , Medicamentos de Ervas Chinesas/química , Antineoplásicos Fitogênicos/metabolismo , Sítios de Ligação , Domínio Catalítico , Medicamentos de Ervas Chinesas/metabolismo , Fosfatases de Especificidade Dupla/antagonistas & inibidores , Fosfatases de Especificidade Dupla/metabolismo , Humanos , Ligantes , Proteína Quinase 3 Ativada por Mitógeno/química , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Termodinâmica
13.
Prog Chem Org Nat Prod ; 110: 99-141, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31621012

RESUMO

Pharmacophore-based techniques currently are an integral part of many computer-aided drug design workflows and have been successfully and extensively applied for tasks such as virtual screening, de novo design, and lead optimization. Pharmacophore models can be derived both in a receptor-based and in a ligand-based manner, and provide an abstract description of essential non-bonded interactions that typically occur between small-molecule ligands and macromolecular targets. Due to their simplistic and abstract nature, pharmacophores are both perfectly suited for efficient computer processing and easy to comprehend by life and physical scientists. As a consequence, they have also proven to be a valuable tool for communicating between computational and medicinal chemists.This chapter aims to provide a short overview of the pharmacophore concept and its applications in modern computer-aided drug design. The chapter is divided into three distinct parts. The first section contains a brief introduction to the pharmacophore concept. The second section provides a description of the most common nonbonded interaction types and their representation as pharmacophoric features. Furthermore, it gives an overview of the various methods for pharmacophore generation and important pharmacophore-based techniques in drug design. This part concludes with examples for recent pharmacophore concept-related research and development. The last section is dedicated to a review of research in the field of natural product chemistry as carried out by employing pharmacophore-based drug design methods.


Assuntos
Química Farmacêutica , Projeto Auxiliado por Computador , Desenho de Drogas , Produtos Biológicos/química , Ligantes , Receptores de Droga
14.
Inorg Chem ; 58(21): 14294-14298, 2019 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-31599154

RESUMO

Metal complexes to promote oxidative DNA cleavage by H2O2 are desirable as anticancer drugs. A dicopper(II) complex of known p-cresol-derived methylene-tether ligand Hbcc [Cu2(bcc)]3+ did not promote DNA cleavage by H2O2. Here, we synthesized a new p-cresol-derived amide-tether one, 2,6-bis(1,4,7,10-tetrazacyclododecyl-1-carboxyamide)-p-cresol (Hbcamide). A dicopper(II) complex of the new ligand [Cu2(µ-OH)(bcamide)]2+ was structurally characterized. This complex promoted the oxidative cleavage of supercoiled plasmid pUC19 DNA (Form I) with H2O2 at pH 6.0-8.2 to give Forms II and III. The reaction was largely accelerated in a high pH region. A µ-1,1-hydroperoxo species was formed as the active species and spectroscopically identified. The amide-tether complex is more effective in cytotoxicity against HeLa cells than the methylene-tether one.


Assuntos
Amidas/farmacologia , Antineoplásicos/farmacologia , Complexos de Coordenação/farmacologia , Cobre/farmacologia , Cresóis/farmacologia , Peróxido de Hidrogênio/farmacologia , Amidas/química , Antineoplásicos/síntese química , Antineoplásicos/química , Proliferação de Células/efeitos dos fármacos , Complexos de Coordenação/síntese química , Complexos de Coordenação/química , Cobre/química , Cresóis/química , Clivagem do DNA , Ensaios de Seleção de Medicamentos Antitumorais , Células HeLa , Humanos , Peróxido de Hidrogênio/síntese química , Peróxido de Hidrogênio/química , Ligantes , Estrutura Molecular , Oxirredução
15.
J Chem Theory Comput ; 15(11): 6225-6242, 2019 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-31603667

RESUMO

Designing ligands that bind their target biomolecules with high affinity and specificity is a key step in small-molecule drug discovery, but accurately predicting protein-ligand binding free energies remains challenging. Key sources of errors in the calculations include inadequate sampling of conformational space, ambiguous protonation states, and errors in force fields. Noncovalent complexes between a host molecule with a binding cavity and a druglike guest molecule have emerged as powerful model systems. As model systems, host-guest complexes reduce many of the errors in more complex protein-ligand binding systems, as their small size greatly facilitates conformational sampling, and one can choose systems that avoid ambiguities in protonation states. These features, combined with their ease of experimental characterization, make host-guest systems ideal model systems to test and ultimately optimize force fields in the context of binding thermodynamics calculations. The Open Force Field Initiative aims to create a modern, open software infrastructure for automatically generating and assessing force fields using data sets. The first force field to arise out of this effort, named SMIRNOFF99Frosst, has approximately one tenth the number of parameters, in version 1.0.5, compared to typical general small molecule force fields, such as GAFF. Here, we evaluate the accuracy of this initial force field, using free energy calculations of 43 α and ß-cyclodextrin host-guest pairs for which experimental thermodynamic data are available, and compare with matched calculations using two versions of GAFF. For all three force fields, we used TIP3P water and AM1-BCC charges. The calculations are performed using the attach-pull-release (APR) method as implemented in the open source package, pAPRika. For binding free energies, the root-mean-square error of the SMIRNOFF99Frosst calculations relative to experiment is 0.9 [0.7, 1.1] kcal/mol, while the corresponding results for GAFF 1.7 and GAFF 2.1 are 0.9 [0.7, 1.1] kcal/mol and 1.7 [1.5, 1.9] kcal/mol, respectively, with 95% confidence ranges in brackets. These results suggest that SMIRNOFF99Frosst performs competitively with existing small molecule force fields and is a parsimonious starting point for optimization.


Assuntos
Ligantes , Modelos Moleculares , Termodinâmica , alfa-Ciclodextrinas/química , beta-Ciclodextrinas/química
16.
Int J Nanomedicine ; 14: 7155-7171, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31564871

RESUMO

Background: Platelet activation and subsequent aggregation are the initial stages of thrombosis. A molecular probe that specifically targets activated platelets and remains retained under high shear stress in vivo can enhance the imaging effect to achieve early and accurate diagnosis. Methods and materials: In this study, we constructed nanoparticles (NPs) using polydopamine to carry two peptides that simultaneously bind integrin αIIbß3 and P-selectin on activated platelets to enhance the targeting of NPs to thrombus. Results: The targeting specificity and binding stability of the NPs on red and white thrombi were demonstrated in vitro using a simulated circulatory device and the targeting effect of the NPs on mixed thrombus was studied by  magnetic resonance (MR)/photoacoustic (PA) dual-modality imaging in vivo. NPs that were surface modified with both peptides have higher selectivity and retention to red and white thrombi in vitro than NPs with a single or no peptide, and the targeting effect was closely related to the number and distribution of activated platelets as well as the structure and type of thrombus. The NPs also have MR/PA dual-modality imaging functionality, significantly enhancing the imaging of mixed thrombus in vivo. Conclusion: These dual-targeted NPs have improved targeting specificity and binding stability to different thrombi under high shear stress and are beneficial for the early diagnosis of thrombosis.


Assuntos
Indóis/química , Imagem por Ressonância Magnética , Nanopartículas/química , Técnicas Fotoacústicas , Polímeros/química , Trombose/diagnóstico por imagem , Animais , Meios de Contraste/química , Humanos , Ligantes , Espectroscopia de Ressonância Magnética , Imagem Molecular , Nanopartículas/ultraestrutura , Ativação Plaquetária , Ratos Sprague-Dawley
17.
Inorg Chem ; 58(20): 13933-13944, 2019 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-31566371

RESUMO

Density functional vibrational frequency calculations have been performed on eight geometry optimized cytochrome c oxidase (CcO) dinuclear center (DNC) reaction cycle intermediates and on the oxymyoglobin (oxyMb) active site. The calculated Fe-O and O-O stretching modes and their frequency shifts along the reaction cycle have been compared with the available resonance Raman (rR) measurements. The calculations support the proposal that in state A[Fea33+-O2-•···CuB+] of CcO, O2 binds with Fea32+ in a similar bent end-on geometry to that in oxyMb. The calculations show that the observed 20 cm-1 shift of the Fea3-O stretching mode from the PR to F state is caused by the protonation of the OH- ligand on CuB2+ (PR[Fea34+═O2-···HO--CuB2+] → F[Fea34+═O2-···H2O-CuB2+]), and that the H2O ligand is still on the CuB2+ site in the rR identified F[Fea34+═O2-···H2O-CuB2+] state. Further, the observed rR band at 356 cm-1 between states PR and F is likely an O-Fea3-porphyrin bending mode. The observed 450 cm-1 low Fea3-O frequency mode for the OH active oxidized state has been reproduced by our calculations on a nearly symmetrically bridged Fea33+-OH-CuB2+ structure with a relatively long Fea3-O distance near 2 Å. Based on Badger's rule, the calculated Fea3-O distances correlate well with the calculated νFe-O-2/3 (νFe-O is the Fea3-O stretching frequency) with correlation coefficient R = 0.973.


Assuntos
Teoria da Densidade Funcional , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Ferro/química , Oxigênio/química , Biocatálise , Domínio Catalítico , Cristalografia por Raios X , Complexo IV da Cadeia de Transporte de Elétrons/química , Ferro/metabolismo , Ligantes , Modelos Moleculares , Oxigênio/metabolismo , Vibração
18.
Anticancer Res ; 39(10): 5531-5539, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31570447

RESUMO

BACKGROUND: Possible correlations between the expression of immune checkpoint molecules and prognosis in childhood acute leukemia were investigated. MATERIALS AND METHODS: The expression of programmed-death 1 (PD1), cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), and B- and T-lymphocyte attenuator (BTLA) was determined by flow cytometry on peripheral αß+ and γδ+ T-cells from patients with newly diagnosed acute lymphoblastic leukemia (ALL) (n=9) or acute myeloid leukemia (AML) (n=12), and from healthy volunteers (n=7). The expression of programmed-death ligand 1 (PD-L1), B7-1, B7-2, human leukocyte antigen-ABC (HLA-ABC), and herpesvirus-entry mediator (HVEM) ligands was determined on leukemia blasts. RESULTS: PD1 expression on αß+ and γδ+ T-cells was significantly higher in patients with ALL than in those with AML (p=0.0019 and 0.0239, respectively). CTLA-4 expression was moderately higher on αß+ and γδ+ T-cells in ALL (p=0.077 and 0.077, respectively), whereas HLA-ABC expression was significantly higher in AML blast cells (p=0.0182). The expression of CTLA-4 on γδ+ T-cells and the B7-2 ligand on blasts was higher in patients with high-risk ALL (p=0.02 and 0.02, respectively). In AML, PD1 expression on αß+ T-cells was higher in the intermediate-risk group (p=0.05), whereas HVEM expression was significantly higher in the low-risk group (p=0.02). Expression of CTLA-4 on γδ+ T-cells and PD-L1 on blasts were both associated with poor relapse-free survival outcomes in ALL (p=0.049). CONCLUSION: The higher expression of immune checkpoint molecules, in particular, CTLA-4 and PD-L1 are associated with a poorer prognosis in ALL, suggesting that selective use of the immune checkpoint blockade might improve the clinical outcomes in patients with ALL.


Assuntos
Leucemia/metabolismo , Leucemia-Linfoma Linfoblástico de Células Precursoras/metabolismo , Linfócitos T/imunologia , Doença Aguda , Adolescente , Adulto , Antígeno B7-H1/metabolismo , Antígeno CTLA-4/metabolismo , Criança , Pré-Escolar , Intervalo Livre de Doença , Feminino , Humanos , Lactente , Ligantes , Masculino , Pessoa de Meia-Idade , Recidiva , Adulto Jovem
19.
Chem Commun (Camb) ; 55(87): 13066-13069, 2019 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-31570904

RESUMO

A platinum(ii) complex containing an aminophosphonate ligand preferentially accumulates in the endoplamic reticulum (ER) in association with potent ER stress and reactive oxygen species generation, followed by the activation of damage-associated molecular pattern signals and immune responses. Importantly, the Pt complex exhibits potent anti-tumour activities in two independent mouse models via an immunogenic cell death pathway.


Assuntos
Antineoplásicos Imunológicos/farmacologia , Ésteres/farmacologia , Neoplasias Pulmonares/tratamento farmacológico , Organofosfonatos/farmacologia , Compostos Organoplatínicos/farmacologia , Animais , Antineoplásicos Imunológicos/química , Morte Celular/efeitos dos fármacos , Ésteres/química , Humanos , Ligantes , Neoplasias Pulmonares/imunologia , Neoplasias Pulmonares/patologia , Camundongos , Camundongos Endogâmicos C57BL , Neoplasias Experimentais/tratamento farmacológico , Neoplasias Experimentais/imunologia , Neoplasias Experimentais/patologia , Organofosfonatos/química , Compostos Organoplatínicos/química
20.
Int J Nanomedicine ; 14: 7399-7417, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31571858

RESUMO

Purpose: We studied the effects of silver nanoparticles (AgNPs) on human blood platelet function. We hypothesized that AgNPs, a known antimicrobial agent, can be used as blood-compatible, "ideal material'' in medical devices or as a drug delivery system. Therefore, the aim of the current study was to investigate if functionalized AgNPs affect platelet function and platelets as well as endothelial cell viability in vitro. Methods: AgNPs, functionalized with reduced glutathione (GSH), polyethylene glycol (PEG) and lipoic acid (LA) were synthesized. Quartz crystal microbalance with dissipation was used to measure the effect of AgNPs on platelet aggregation. Platelet aggregation was measured by changes in frequency and dissipation, and the presence of platelets on the sensor surface was confirmed and imaged by phase contrast microscopy. Flow cytometry was used to detect surface abundance of platelet receptors. Lactate dehydrogenase test was used to assess the potential cytotoxicity of AgNPs on human blood platelets, endothelial cells, and fibroblasts. Commercially available ELISA tests were used to measure the levels of thromboxane B2 and metalloproteinases (MMP-1, MMP-2) released by platelets as markers of platelet activation. Results: 2 nm AgNPs-GSH, 3.7 nm AgNPs-PEG both at 50 and 100 µg/mL, and 2.5 nm AgNPs-LA at 100 µg/mL reduced platelet aggregation, inhibited collagen-mediated increase in total P-selectin and GPIIb/IIIa, TXB2 formation, MMP-1, and MMP-2 release. The tested AgNPs concentrations were not cytotoxic as they did not affect, platelet, endothelial cell, or fibroblast viability. Conclusion: All tested functionalized AgNPs inhibited platelet aggregation at nontoxic concentrations. Therefore, functionalized AgNPs can be used as an antiplatelet agent or in design and manufacturing of blood-facing medical devices, such as vascular grafts, stents, heart valves, and catheters.


Assuntos
Plaquetas/efeitos dos fármacos , Nanopartículas Metálicas/química , Agregação Plaquetária/efeitos dos fármacos , Prata/farmacologia , Colágeno/metabolismo , Fibroblastos/efeitos dos fármacos , Citometria de Fluxo , Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Células Endoteliais da Veia Umbilical Humana/metabolismo , Humanos , L-Lactato Desidrogenase/metabolismo , Ligantes , Metaloproteinases da Matriz/metabolismo , Nanopartículas Metálicas/ultraestrutura , Selectina-P/metabolismo , Tamanho da Partícula , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/metabolismo , Polietilenoglicóis/química , Técnicas de Microbalança de Cristal de Quartzo , Espectroscopia de Infravermelho com Transformada de Fourier , Tromboxano B2/metabolismo
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