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1.
Nat Commun ; 12(1): 648, 2021 01 28.
Artigo em Inglês | MEDLINE | ID: mdl-33510170

RESUMO

Controlling nanocarrier interactions with the immune system requires a thorough understanding of the surface properties that modulate protein adsorption in biological fluids, since the resulting protein corona redefines cellular interactions with nanocarrier surfaces. Albumin is initially one of the dominant proteins to adsorb to nanocarrier surfaces, a process that is considered benign or beneficial by minimizing opsonization or inflammation. Here, we demonstrate the surface chemistry of a model nanocarrier can be engineered to stabilize or denature the three-dimensional conformation of adsorbed albumin, which respectively promotes evasion or non-specific clearance in vivo. Interestingly, certain common chemistries that have long been considered to convey stealth properties denature albumin to promote nanocarrier recognition by macrophage class A1 scavenger receptors, providing a means for their eventual removal from systemic circulation. We establish that the surface chemistry of nanocarriers can be specified to modulate adsorbed albumin structure and thereby tune clearance by macrophage scavenger receptors.


Assuntos
Macrófagos/metabolismo , Nanopartículas/química , Dobramento de Proteína , Soroalbumina Bovina/química , Adsorção , Animais , Bovinos , Microscopia Crioeletrônica , Humanos , Cinética , Camundongos , Camundongos Endogâmicos C57BL , Microscopia Eletrônica de Transmissão , Nanopartículas/ultraestrutura , Coroa de Proteína/química , Coroa de Proteína/metabolismo , Células RAW 264.7 , Receptores Depuradores/química , Receptores Depuradores/metabolismo , Soroalbumina Bovina/metabolismo , Propriedades de Superfície
2.
Ecotoxicol Environ Saf ; 207: 111280, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-32937227

RESUMO

As a top-selling neonicotinoid insecticide widely used in the field, thiamethoxam is an environmental pollutant because of the accumulation in ecosystem and has also been reported that it has potential risks to the health of mammals even humans. In order to understand the binding mechanism of thiamethoxam with biological receptors, spectroscopic techniques and theoretical simulations was used to explore the specific interactions between thiamethoxam and proteins. Interestingly, the results indicated that hydrophobic interaction as the main driving force, thiamethoxam formed a single binding site complex with proteins spontaneously, resulting in a decrease in the esterase-like activity of human serum albumin. The results of computer simulation showed that there were hydrophobic, electrostatic and hydrogen bonding interactions between thiamethoxam and receptors. The results of experiment and computer simulation were mutually confirmed, so a model was established for the interaction between the two which uncovered the structural characteristics of the binding site. This research provided new insights for the structure optimization of thiamethoxam, as well as gave an effective reference for evaluating the risk of thiamethoxam systemically in the future.


Assuntos
Inseticidas/química , Modelos Químicos , Soroalbumina Bovina/química , Albumina Sérica Humana/química , Tiametoxam/química , Animais , Sítios de Ligação , Ligação Competitiva , Simulação por Computador , Ecossistema , Esterases/química , Esterases/metabolismo , Humanos , Interações Hidrofóbicas e Hidrofílicas , Ligantes , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Ligação Proteica , Soroalbumina Bovina/metabolismo , Albumina Sérica Humana/metabolismo , Espectrometria de Fluorescência , Varfarina/química
3.
Chem Biol Interact ; 335: 109364, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33359597

RESUMO

Metallic nanoparticles are an important and widely used materials in development of nano-enabled medicine. For that reason, their interaction with biological molecules has to be systematically examined, as use of nanoparticles can lead to altered biological functions. In this study, we evaluated the interaction between silver nanoparticles (AgNPs) and two important plasma transport proteins - albumin and α-1-acid glycoprotein. To investigate comprehensively how different physico-chemical properties impact interaction of proteins with nanosurface, AgNPs of different size, shape and surface coating was prepared. The study was conducted using UV-Vis absorption, fluorescence, inductively coupled plasma mass spectrometry, circular dichroism spectroscopy, transmission electron microscopy, dynamic and electrophoretic light scattering techniques. The results showed significant complexities of the nano-bio interface and binding affinities of proteins onto surface of different AgNPs, which were affected by both AgNPs and protein properties. The most significant role on AgNPs-protein interaction had the coating agents used for AgNPs surface stabilization. Our findings should improve safe-by-design approach to development of the metallic nanomaterials for medical use.


Assuntos
Nanopartículas Metálicas/química , Orosomucoide/metabolismo , Soroalbumina Bovina/metabolismo , Animais , Bovinos , Orosomucoide/química , Tamanho da Partícula , Polímeros/química , Ligação Proteica , Conformação Proteica/efeitos dos fármacos , Soroalbumina Bovina/química , Prata/química , Tensoativos/química
4.
Food Chem ; 333: 127432, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32659661

RESUMO

The sensory qualities and shelf life of tea beverage strongly affected by tea cream that forms by the interaction of polyphenols and protein. The study aimed to investigate the effects of the interactions between tea polyphenols (TPs) and bovine serum albumin (BSA) on tea cream formation at different concentrations. The tea cream formation increased with TPs and BSA concentration increased. The optimal concentration (TPs: 800 mg/L, BSA: 40 mg/L), for high clarities and contents of phytochemicals, was selected by the technique for order preference by similarity to ideal solution (C = 0.7572). The interaction mechanism of TPs-BSA was investigated by fluorescence spectroscopy, UV-visible absorption spectroscopy, synchronous fluorescence spectroscopy, and molecular docking. TPs interacted with BSA via static quenching process, affecting tryptophan and tyrosine residue microenvironment of BSA. Ester catechins had more binding affinity than non-ester catechins. Hydrogen bonds were the main interaction forces of TPs-BSA.


Assuntos
Polifenóis/química , Polifenóis/metabolismo , Soroalbumina Bovina/química , Chá/química , Animais , Sítios de Ligação , Catequina/química , Catequina/metabolismo , Precipitação Química , Ligação de Hidrogênio , Simulação de Acoplamento Molecular , Tamanho da Partícula , Soroalbumina Bovina/metabolismo , Espectrometria de Fluorescência , Espectrofotometria Ultravioleta , Chá/metabolismo , Termodinâmica
5.
Food Chem ; 332: 127302, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32615389

RESUMO

The study aimed to evaluate the inhibitory effects of Centella asiatica phenolics (CAP) on bovine serum albumin glycoxidation in a BSA-glucose model in vitro. The impact of the phenolic extract on the formation of total fluorescent advanced glycation end products (AGEs) and Amadori adducts were determined. Dityrosine, N-formylkynurenine, kynurenine and protein-carbonyls were quantified as markers of protein oxidation. Protein structural perturbations were determined by Congo red binding and FTIR analysis. Chemical characterization and CAP phytoconstituent profile was obtained by colorimetric and UHPLC-ESI-qTOF-MS analysis, respectively. Our data show that CAP attenuated the formation of fluorescent AGEs (38.5%), Dityrosine (44.6%), N-formylkynurenine (42.9%), Amadori products, and resisted structural alterations of BSA subjected to glycation. These effects could be due to the antioxidant and radical scavenging activities of CAP mediated by the presence of phenolics and triterpenoids. The results collectively suggest that CAP possesses antiglycative properties with potentials for nutraceutical applications.


Assuntos
Antioxidantes/farmacologia , Centella/química , Glucose/metabolismo , Fenóis/farmacologia , Soroalbumina Bovina/metabolismo , Animais , Bovinos , Glicosilação/efeitos dos fármacos , Oxirredução
6.
Nat Commun ; 11(1): 3244, 2020 06 26.
Artigo em Inglês | MEDLINE | ID: mdl-32591520

RESUMO

Bioorthogonal chemistry introduces affinity-labels into biomolecules with minimal disruption to the original system and is widely applicable in a range of contexts. In proteomics, immobilized metal affinity chromatography (IMAC) enables enrichment of phosphopeptides with extreme sensitivity and selectivity. Here, we adapt and combine these superb assets in a new enrichment strategy using phosphonate-handles, which we term PhosID. In this approach, click-able phosphonate-handles are introduced into proteins via 1,3-dipolar Huisgen-cycloaddition to azido-homo-alanine (AHA) and IMAC is then used to enrich exclusively for phosphonate-labeled peptides. In interferon-gamma (IFNγ) stimulated cells, PhosID enabled the identification of a large number of IFN responsive newly synthesized proteins (NSPs) whereby we monitored the differential synthesis of these proteins over time. Collectively, these data validate the excellent performance of PhosID with efficient analysis and quantification of hundreds of NSPs by single LC-MS/MS runs. We envision PhosID as an attractive and alternative tool for studying stimuli-sensitive proteome subsets.


Assuntos
Organofosfonatos/metabolismo , Biossíntese de Proteínas , Animais , Biotina/metabolismo , Bovinos , Células HeLa , Humanos , Interferon gama/farmacologia , Células Jurkat , Organofosfonatos/química , Peptídeos/metabolismo , Biossíntese de Proteínas/efeitos dos fármacos , Soroalbumina Bovina/metabolismo , Coloração e Rotulagem , Estreptavidina/metabolismo
7.
Sci Rep ; 10(1): 8074, 2020 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-32415277

RESUMO

Interactions between proteins and ligands, which are fundamental to many biochemical processes essential to life, are mostly studied at dilute buffer conditions. The effects of the highly crowded nature of biological cells and the effects of liquid-liquid phase separation inducing biomolecular droplet formation as a means of membrane-less compartmentalization have been largely neglected in protein binding studies. We investigated the binding of a small ligand (ANS) to one of the most multifunctional proteins, bovine serum albumin (BSA) in an aqueous two-phase system (ATPS) composed of PEG and Dextran. Also, aiming to shed more light on differences in binding mode compared to the neat buffer data, we examined the effect of high hydrostatic pressure (HHP) on the binding process. We observe a marked effect of the ATPS on the binding characteristics of BSA. Not only the binding constants change in the ATPS system, but also the integrity of binding sites is partially lost, which is most likely due to soft enthalpic interactions of the BSA with components in the dense droplet phase of the ATPS. Using pressure modulation, differences in binding sites could be unravelled by their different volumetric and hydration properties. Regarding the vital biological relevance of the study, we notice that extreme biological environments, such as HHP, can markedly affect the binding characteristics of proteins. Hence, organisms experiencing high-pressure stress in the deep sea need to finely adjust the volume changes of their biochemical reactions in cellulo.


Assuntos
Naftalenossulfonato de Anilina/química , Soroalbumina Bovina/química , Soroalbumina Bovina/metabolismo , Estresse Mecânico , Água/química , Animais , Bovinos , Interações Hidrofóbicas e Hidrofílicas , Pressão , Ligação Proteica , Conformação Proteica
8.
AAPS PharmSciTech ; 21(4): 134, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-32415347

RESUMO

This work described the development of a cationic polylactic acid (PLA)-based nanoparticles (NPs) as an antigen delivery system using dimethyldioctadecylammonium bromide (DDA) to facilitate the engulfment of BSA-FITC by porcine alveolar macrophages (3D4/2 cells) and heat-labile enterotoxin subunit B (LTB) to enhance the transport of BSA-FITC across M cells. The experimental design methodology was employed to study the influence of PLA, polyvinyl alcohol (PVA), DDA, and LTB on the physical properties of the PLA-based NPs. The size of selected cationic PLA NPs comprising 5% PLA, 5% PVA, and 0.6% DDA with or without LTB absorption was range from 367 to 390 nm with a polydispersity index of 0.26, a zeta potential of + 26.00 to + 30.55 mV, and entrapment efficiency of 41.43%. Electron micrographs revealed NPs with spherical shape. The release kinetic of BSA from the NPs followed the Korsmeyer-Peppas kinetics. The cationic PLA NPs with LTB surface absorption showed 3-fold increase in BSA-FITC transported across M cells compared with the NPs without LTB absorption. The uptake studies demonstrated 2-fold increase in BSA-FITC intensity in 3D4/2 cells with cationic NPs as compared with anionic NPs. Overall, the results suggested that LTB decreased the retention time of BSA-FITC loaded in the cationic PLA NPs within the M cells, thus promoting the transport of BSA-FITC across the M cells, and cationic NPs composed of DDA help facilitate the uptake of BSA-FITC in the 3D4/2 cells. Further studies in pigs with respiratory antigens will provide information on the efficacy of cationic PLA NPs as a nasal antigen carrier system.


Assuntos
Fluoresceína-5-Isotiocianato/análogos & derivados , Macrófagos Alveolares/metabolismo , Nanopartículas/metabolismo , Poliésteres/metabolismo , Soroalbumina Bovina/metabolismo , Animais , Cátions , Linhagem Celular , Técnicas de Cocultura , Fluoresceína-5-Isotiocianato/administração & dosagem , Fluoresceína-5-Isotiocianato/química , Fluoresceína-5-Isotiocianato/metabolismo , Macrófagos Alveolares/efeitos dos fármacos , Nanopartículas/administração & dosagem , Nanopartículas/química , Tamanho da Partícula , Poliésteres/administração & dosagem , Poliésteres/química , Soroalbumina Bovina/administração & dosagem , Soroalbumina Bovina/química , Suínos
9.
Food Chem ; 324: 126872, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32344347

RESUMO

Fluorescence techniques and circular dichroism (CD) were utilized to investigate the interactions of a typical gallotannin 1,2,3,4,6-penta-O-galloyl-ß-D-glucopyranose (PGG) and two simple phenolic compounds ellagic acid (EA) and gallic acid (GA) with bovine serum albumin (BSA). Fluorescence experiments showed that PGG and EA could strongly interact with BSA. The binding constants showed a pH-dependent binding of phenolic acids by BSA. The CD spectra revealed that GA, EA and PGG has slight effect on the secondary structure of BSA at the low concentration (50 µM). However, obvious alterations of the secondary structure of BSA were observed at high concentrations (from 100 µM to 500 µM). The interaction of GA, EA and PGG at high concentrations with BSA caused an unfolding of the secondary structure of BSA. PGG has a greater impact on the secondary structure of BSA when compared with small molecule compounds GA and EA.


Assuntos
Ácido Elágico/química , Ácido Gálico/química , Taninos Hidrolisáveis/química , Soroalbumina Bovina/química , Espectrometria de Fluorescência , Animais , Bovinos , Dicroísmo Circular , Ácido Elágico/metabolismo , Ácido Gálico/metabolismo , Concentração de Íons de Hidrogênio , Taninos Hidrolisáveis/metabolismo , Ligação Proteica , Estrutura Secundária de Proteína , Soroalbumina Bovina/metabolismo
10.
Sci Rep ; 10(1): 6534, 2020 04 16.
Artigo em Inglês | MEDLINE | ID: mdl-32300169

RESUMO

Novel derivatives possessing imidazo[1,2-a]pyrazine and 1H-benzo[d]imidazole scaffolds were synthesized using Suzuki-Miyaura cross-coupling reactions. In vitro anticancer activities against NCI-60 cancer cell panels were tested at 10 µM concentration. The best results were obtained from substitution of two 1-cyclohexyl-1H-benzo[d]imidazole groups present at C-6 and C-8 positions of imidazo[1,2-a]pyrazine (31). Compound 31 was found to be cytotoxic against 51 cell lines and cytostatic against 8 cell lines with broad range of growth inhibitions (-98.48 to 98.86%). GI50 value of compound 31 was found in the range of 0.80-2.87 µM for 59 human cancer cell lines at five-dose concentration levels. DNA binding study of potent compound 31 was suggested that this compound was intercalated into DNA base pairs with binding constant of 1.25 × 104 M-1. Compound 31 showed effective binding with bovine serum albumin (BSA) and presented binding constant value of 3.79 ×104 M-1. Pharmacokinetic studies revealed that all compounds are following Lipinski's rule of five and expected to be orally active.


Assuntos
DNA/metabolismo , Imidazóis/síntese química , Imidazóis/farmacocinética , Soroalbumina Bovina/metabolismo , Animais , Ligação Competitiva , Bovinos , Morte Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Etídio/metabolismo , Transferência Ressonante de Energia de Fluorescência , Células HEK293 , Humanos , Imidazóis/química , Imidazóis/farmacologia , Simulação de Acoplamento Molecular , Desnaturação de Ácido Nucleico , Ligação Proteica , Espectrometria de Fluorescência , Temperatura
11.
AAPS PharmSciTech ; 21(4): 122, 2020 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-32337617

RESUMO

This study aimed to investigate the effect of pH-mediated surface properties of bovine serum albumin (BSA) on protein aggregation and the changes of protein structure and colloidal stability at different solution pH levels. The hydrophobicity of BSA surface was characterized by endogenous fluorescence spectroscopy, fluorescence quenching of acrylamide, and fluorescence probe. The results showed that the hydrophobicity of BSA surface was similar at pH 5, 6, 7.4, followed by pH 4, 8, 9, 10, and finally by pH 3 and 11 with strong acidity and alkalinity. The positive charge on the BSA surface was increased gradually with the decrease of solution pH, while the negative charge on protein surface was increased gradually with the increase of solution pH. The degree of protein aggregation was examined by turbidimetry, flow cytometry, and SDS-PAGE. The results showed that the oscillating aggregation of BSA did not change with the solution pH, but was partially dependent on the relative contribution of electrostatic and hydrophobic interactions between the protein molecules. In addition, the secondary structure, conformational stability, unfolding degree, and colloidal stability of proteins were investigated by circular dichroism, fluorescence spectroscopy, protein pulse hydrolysis, and dynamic light scattering, respectively. The results suggested that the solution pH could change the structure and stability of the protein at different levels. Solution pH has distinct effects on the structural stability of protein at different levels. The change of protein surface properties mediated by solution pH is related to protein aggregation.


Assuntos
Agregados Proteicos , Soroalbumina Bovina/química , Água/química , Animais , Bovinos , Dicroísmo Circular/métodos , Corantes Fluorescentes/química , Corantes Fluorescentes/metabolismo , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Estrutura Secundária de Proteína , Soroalbumina Bovina/metabolismo , Espectrometria de Fluorescência/métodos , Eletricidade Estática , Propriedades de Superfície , Água/metabolismo
12.
Int J Mol Sci ; 21(5)2020 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-32155814

RESUMO

The main coffee diterpenes cafestol, kahweol, and 16-O-methylcafestol, present in the bean lipid fraction, are mostly esterified with fatty acids. They are believed to induce dyslipidaemia and hypercholesterolemia when taken with certain types of coffee brews. The study of their binding to serum albumins could help explain their interactions with biologically active xenobiotics. We investigated the interactions occurring between cafestol and 16-O-methylcafestol palmitates with Bovine Serum Albumin (BSA), Human Serum Albumin (HSA), and Fatty Free Human Serum Albumin (ffHSA) by means of circular dichroism and fluorimetry. Circular Dichroism (CD) revealed a slight change (up to 3%) in the secondary structure of fatty-free human albumin in the presence of the diterpene esters, suggesting that the aliphatic chain of the palmitate partly occupies one of the fatty acid sites of the protein. A warfarin displacement experiment was performed to identify the binding site, which is probably close but not coincident with Sudlow site I, as the affinity for warfarin is enhanced. Fluorescence quenching titrations revealed a complex behaviour, with Stern-Volmer constants in the order of 103-104 Lmol-1. A model of the HSA-warfarin-cafestol palmitate complex was obtained by docking, and the most favourable solution was found with the terpene palmitate chain inside the FA4 fatty acid site and the cafestol moiety fronting warfarin at the interface with site I.


Assuntos
Diterpenos/metabolismo , Ácidos Graxos não Esterificados/metabolismo , Soroalbumina Bovina/metabolismo , Albumina Sérica Humana/metabolismo , Animais , Sítios de Ligação , Bovinos , Café , Diterpenos/química , Ácidos Graxos não Esterificados/química , Humanos , Modelos Moleculares , Ligação Proteica , Conformação Proteica , Soroalbumina Bovina/química , Albumina Sérica Humana/química
13.
Sci Rep ; 10(1): 5120, 2020 03 20.
Artigo em Inglês | MEDLINE | ID: mdl-32198463

RESUMO

More than 20 unique diseases such as diabetes, Alzheimer's disease, Parkinson's disease are caused by the abnormal aggregations of pathogenic proteins such as amylin, ß-amyloid (Aß), and α-synuclein. All pathogenic proteins differ from each other in biological function, primary sequences, and morphologies; however, the proteins are toxic when aggregated. Here, we investigated the cellular toxicity of pathogenic or non-pathogenic protein aggregates. In this study, six proteins were selected and they were incubated at acid pH and high temperature. The aggregation kinetic and cellular toxicity of protein species with time were characterized. Three non-pathogenic proteins, bovine serum albumin (BSA), catalase, and pepsin at pH 2 and 65 °C were stable in protein structure and non-toxic at a lower concentration of 1 mg/mL. They formed aggregates at a higher concentration of 20 mg/mL with time and they induced the toxicity in short incubation time points, 10 min and 20 min only and they became non-toxic after 30 min. Other three pathogenic proteins, lysozyme, superoxide dismutase (SOD), and insulin, also produced the aggregates with time and they caused cytotoxicity at both 1 mg/mL and 20 mg/mL after 10 min. TEM images and DSC analysis demonstrated that fibrils or aggregates at 1 mg/mL induced cellular toxicity due to low thermal stability. In DSC data, fibrils or aggregates of pathogenic proteins had low thermal transition compared to fresh samples. The results provide useful information to understand the aggregation and cellular toxicity of pathogenic and non-pathogenic proteins.


Assuntos
Catalase/metabolismo , Insulina/metabolismo , Muramidase/metabolismo , Pepsina A/metabolismo , Agregados Proteicos/fisiologia , Agregação Patológica de Proteínas/patologia , Soroalbumina Bovina/metabolismo , Superóxido Dismutase/metabolismo , Doença de Alzheimer/genética , Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/metabolismo , Linhagem Celular , Diabetes Mellitus/genética , Diabetes Mellitus/patologia , Humanos , Polipeptídeo Amiloide das Ilhotas Pancreáticas/metabolismo , Modelos Moleculares , Doença de Parkinson/genética , Doença de Parkinson/patologia , Estrutura Secundária de Proteína/fisiologia , alfa-Sinucleína/metabolismo
14.
Food Chem ; 315: 126265, 2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-32014668

RESUMO

Protein glycation plays a vital role in the progression of various diabetes complications. Therefore, inhibition of protein glycation could be a key strategy to prevent these diabetic abnormalities. Evaluation of phenolic compositions and their antiglycation activity revealed that p-coumaric and chlorogenic acids were major phenolic acids in barnyard millet. These phenolics exhibited multiple antioxidant activities in various mechanisms and protected the oxidative DNA damage and hydroxyl radical-induced protein fragmentation. Millet phenolics were very effective in scavenging >78% reactive carbonyl intermediates in the reaction and protected protein thiol group oxidation. Furthermore, 68.3% inhibition of protein glycation and reduced formation of protein aggregates were also observed with millet phenolics. Besides, fluorescence intensity measurements indicated a significant decrease in advance glycated end products and protection against glycoxidation-induced protein conformational changes at 100 µg/ml phenolics. These results suggest the potential utility of barnyard millet as an ingredient in functional foods for controlling protein glycation associated diabetic complications.


Assuntos
Echinochloa/química , Produtos Finais de Glicação Avançada/metabolismo , Fenóis/farmacologia , Proteínas/metabolismo , Antioxidantes/análise , Antioxidantes/farmacologia , Frutose/metabolismo , Produtos Finais de Glicação Avançada/efeitos dos fármacos , Oxirredução , Fenóis/análise , Fenóis/isolamento & purificação , Extratos Vegetais/química , Proteínas/química , Soroalbumina Bovina/metabolismo
15.
J Environ Sci Health B ; 55(6): 509-516, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32037956

RESUMO

This study investigates the interaction between tebuconazole and bovine serum albumin (BSA) in a physiological buffer (pH = 7.4) using the fluorescence quenching method to obtain the apparent binding constants (K) and number of binding sites (n) in the interaction between tebuconazole and BSA. The results revealed that tebuconazole can quench the intrinsic fluorescence of BSA through a static quenching procedure. It also shows that the thermodynamic parameters of enthalpy change (ΔH) and entropy change (ΔS) are negative, indicating that the interaction of tebuconazole with BSA is mainly driven by van der Waals forces and hydrogen bonds. The process of binding was a spontaneous process in which Gibbs free energy change was negative. The distance of r between the donor (BSA) and acceptor (tebuconazole) was calculated to be 0.68 nm based on Forster's non-radiative energy transfer theory. Analysis of synchronous fluorescence, three-dimensional fluorescence and circular dichroism (CD) spectra demonstrates that tebuconazole can induce conformational changes of BSA.


Assuntos
Soroalbumina Bovina/química , Soroalbumina Bovina/metabolismo , Triazóis/metabolismo , Sítios de Ligação , Dicroísmo Circular , Entropia , Fluorescência , Ligação de Hidrogênio , Conformação Proteica , Espectrometria de Fluorescência , Espectrofotometria Ultravioleta , Termodinâmica , Triazóis/química , Triazóis/toxicidade
16.
Spectrochim Acta A Mol Biomol Spectrosc ; 230: 118074, 2020 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-31981855

RESUMO

Folic acid is a bioactive food component whose deficiency can lead to a variety of health problems, while a high intake of folic acid can reduce the cytotoxicity of natural killer cells. The binding mechanism of folic acid to free bovine serum albumin (BSA) was studied using fluorescence, while the biomolecular interaction between confined-BSA and free folic acid was assessed by electrochemical methods and surface plasmon resonance. The fluorescence quenching mechanism of BSA by folic acid was found to have a static character. The thermodynamic parameters of the interaction were determined and indicated a spontaneous exothermic process with a binding constant of 8.72 × 104 M-1 at 25 °C. Confinement of BSA to gold surfaces occurred through different immobilization methods (static and hydrodynamic), inducing conformational changes, which influenced the orientation of BSA molecules binding sites towards free folic acid. The apparent binding constant using electrochemical methods (voltammetry and impedance spectroscopy) was only 5 times higher (41 and 37 × 104 M-1) compared to BSA free in solution, while for surface plasmon resonance, where the hydrodynamic immobilization method was used, the value was much higher (19 × 106 M-1). This work gives also an insight on the interaction of BSA with gold substrates, surface plasmon resonance enabling the calculation of the adsorbed amount. The obtained results help understanding the specific interaction between free and confined BSA with free folic acid.


Assuntos
Técnicas Eletroquímicas/métodos , Ácido Fólico/metabolismo , Soroalbumina Bovina/metabolismo , Espectrometria de Fluorescência/métodos , Ressonância de Plasmônio de Superfície/métodos , Animais , Sítios de Ligação , Bovinos , Ligação Proteica , Termodinâmica
17.
Food Chem ; 315: 126228, 2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-31991257

RESUMO

Monascin (MS) is a yellow lipid-soluble azaphilonoid pigment identified from Monascus-fermented products with promising biological activities. This work studied interactions between MS and bovine serum albumin (BSA) as well as their influences on the antioxidant activity of MS. Experimental results demonstrated that the fluorescence emission of BSA was quenched by MS via static quenching mechanism and the formed BSA-MS complex was mainly maintained by hydrophobic and hydrogen bond interactions. Meanwhile, the probable binding pocket of MS located near site I of BSA and the corresponding conformational and structural alterations of BSA were determined. Furthermore, the molecular modeling approach was performed to understand the visual representation of binding mode between BSA and MS. It was noticeable that the BSA-MS complex exhibited reduced DPPH radical-scavenging ability, which might be attributed to the restraining effect of BSA on the relevant reaction pathways involved in antioxidation by MS.


Assuntos
Antioxidantes/metabolismo , Compostos Heterocíclicos com 3 Anéis/metabolismo , Modelos Moleculares , Soroalbumina Bovina/metabolismo , Animais , Sítios de Ligação , Interações Hidrofóbicas e Hidrofílicas , Simulação de Acoplamento Molecular , Estresse Oxidativo , Ligação Proteica , Espectrometria de Fluorescência , Termodinâmica
18.
Nanoscale ; 12(6): 3630-3636, 2020 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-31998910

RESUMO

Plant nanobiotechnology has the potential to revolutionize agriculture. However, the lack of effective methods to deliver nanoparticles (NPs) to the precise locations in plants where they are needed impedes these technological innovations. Here, model gold nanoparticles (AuNP) were coated with citrate, bovine serum albumin (BSA) as a protein control, or LM6-M, an antibody with an affinity for functional groups unique to stomata on leaf surfaces to deliver the AuNPs to stomata. One-month-old Vicia faba leaves were exposed via drop deposition to aqueous suspensions of LM6-M-coated AuNPs and allowed to air dry. After rinsing, Au distribution on the leaf surface was investigated by enhanced dark-field microscopy and X-ray fluorescence mapping. While citrate-coated AuNPs randomly covered the plant leaves, LM6M-AuNPs strongly adhered to the stomata and remained on the leaf surface after rinsing, and BSA-AuNPs specifically targeted trichome hairs. To the authors' knowledge, this is the first report of active targeting of live leaf structures using NPs coated with molecular recognition molecules. This proof-of-concept study provides a strategy for future targeted nanopesticide delivery research.


Assuntos
Anticorpos/metabolismo , Ouro/metabolismo , Nanopartículas Metálicas/química , Estômatos de Plantas/metabolismo , Tricomas/metabolismo , Anticorpos/química , Citratos/química , Citratos/metabolismo , Ouro/química , Estômatos de Plantas/química , Soroalbumina Bovina/química , Soroalbumina Bovina/metabolismo , Tricomas/química , Vicia faba/química , Vicia faba/metabolismo
19.
Spectrochim Acta A Mol Biomol Spectrosc ; 230: 118063, 2020 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-32000060

RESUMO

In the present study the binding of diversin (DIV), a prenylated coumarin isolated from Ferula diversivittata, to bovine serum albumin (BSA) was investigated using surface plasmon resonance (SPR), spectrofluorimetry, and molecular docking approaches. Following the activation of carboxylic groups, via NHS/EDC, BSA was immobilized on the carboxymethyl dextran (CMD) hydrogel coated Au sensor, and was used for real-time monitoring of the interactions between DIV and BSA. KD value of DIV binding to BSA increased with increasing temperature, confirmed that the affinity between BSA and DIV decreases with rising temperature. In addition, the fluorescence and synchronous fluorescence spectroscopic data revealed that the intrinsic emission intensity of BSA was quenched via a dynamic mechanism. In addition, the micro-region around BSA tyrosine residue was changed upon interaction with DIV. The thermodynamic parameter findings suggested that the hydrophobic interactions were dominant in the binding and formation of the BSA and DIV complex. The molecular docking outputs indicated that there is only one binding site on BSA for DIV, in agreement with experimental data, and DIV bind BSA in subdomain IB.


Assuntos
Cumarínicos/química , Cumarínicos/metabolismo , Ferula/metabolismo , Fluorescência , Simulação de Acoplamento Molecular , Monoterpenos/química , Monoterpenos/metabolismo , Soroalbumina Bovina/química , Soroalbumina Bovina/metabolismo , Ressonância de Plasmônio de Superfície , Animais , Sítios de Ligação , Bovinos , Interações Hidrofóbicas e Hidrofílicas , Ligação Proteica , Espectrometria de Fluorescência , Termodinâmica
20.
Carbohydr Polym ; 232: 115802, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31952601

RESUMO

A series of biocompatible and non- toxic polysaccharide molecules have been successfully fabricated and explored their potential application for scavenging the carbonyl species in vitro. These macromolecules were dextrans with different hydrazide substitution ratios determined by TNBS assay, NMR and FTIR characterization. The colorimetric assay had demonstrated that these macromolecules could effectively scavenge acrolein, oxidized bovine serum albumin (BSA) in buffer solutions as well as carbonyl proteins from serum. The scavengers could achieve twice more scavenging effects for modified dextrans with high molecular weight (Mw = 100,000) than those of low ones (Mw = 40,000) with the same substitution ratio. Protein gel electrophoresis confirmed that the formation of the complex between carbonyls and modified dextrans resulted in appearance of slower bands. It also revealed that such macromolecules could protect cultured cells against the toxicity of acrolein or its derivatives. The proposed macromolecules indicated a very promising capability as scavengers for oxidative stress plus its derivatives without side effects.


Assuntos
Dextranos/metabolismo , Depuradores de Radicais Livres/metabolismo , Hidrazinas/metabolismo , Soroalbumina Bovina/metabolismo , Animais , Bovinos , Dextranos/química , Depuradores de Radicais Livres/química , Hidrazinas/química , Estrutura Molecular , Carbonilação Proteica , Soroalbumina Bovina/química
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