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1.
Chem Res Toxicol ; 36(6): 926-933, 2023 06 19.
Artículo en Inglés | MEDLINE | ID: mdl-37261822

RESUMEN

Drosophila shares maximum homology with the human disease-causing genes and thus has been employed to evaluate the toxicity of numerous compounds. Further, its distinguishable developmental stages, easy rearing, and short lifespan make it a perfect model organism to study toxicological properties of any new compound. The current study evaluates the toxic effect of a coumarin-based organic fluorescent dye, 7-hydroxy-4-methyl-8-((4-(2-oxo-2H-chromen-3-yl)thiazol-2-ylimino)methyl)-2H-chromen-2-one (CTC), using Drosophila melanogaster as a model organism by studying different behavioral, screening, and staining techniques using Oregon-R flies. For toxicity assessment, one control fly group was compared with various flies that had been subjected to fed CTC dye orally of different concentrations (0.5, 1, 2.5, and 5 µg/mL). The 3rd instar larvae were checked for the larvae crawling assay. The crawling assay demonstrates that the speed and path of the treated larvae are almost equal to the control ones, which signifies the non-neurotoxic property of CTC. Trypan blue assay further suggested that the dye does not cause any major damage to the gut. Phalloidin staining revealed that the actin composition remains unaltered even after the CTC treatment, while the DAPI staining experiment indicates that CTC does not cause any nuclear damage to fly gut cells. However, at a concentration of 5 µg/mL, CTC causes developmental delay. The flies hatched after larval treatment of CTC do not show any structural defects, suggesting clearly that CTC is also nongenotoxic to Drosophila. The current studies propose CTC as a noncytotoxic and nongenotoxic dye to track actin protein in the model organism D. melanogaster.


Asunto(s)
Actinas , Drosophila melanogaster , Humanos , Animales , Drosophila melanogaster/genética , Colorantes Fluorescentes/farmacología , Cumarinas/farmacología , Larva
2.
Bioconjug Chem ; 33(11): 2113-2120, 2022 11 16.
Artículo en Inglés | MEDLINE | ID: mdl-36264777

RESUMEN

Selective fluorescence imaging of actin protein hugely depends on the fluorescently labeled actin-binding domain (ABD). Thus, it is always a challenging task to image the actin protein (in vivo or in vitro) directly with an ABD-free system. To overcome the limitations of actin imaging without an ABD, we have designed a facile and cost-effective red fluorescent coumarin dye 7-hydroxy-4-methyl-8-(4-(2-oxo-2H-chromen-3-yl)thiazol-2-ylimino)methyl-2H-chromen-2-one (CTC) for actin binding. The selective binding of the dye was investigated using the gut and eye of the model organism Drosophila melanogaster and C2C12 and SCC-9 cell lines. Our result suggests two major advantages of CTC over the dyes presently used for imaging actin proteins. First, the dye can bind to actin efficiently without any secondary intermediate. Second, it is much more stable at room temperature and exhibits excellent photostability. To the best of our knowledge, this is the first fluorescent dye that can bind to the actin protein without employing any secondary intermediate/actin-binding domain. These findings could pave the way for many biologists and physicists to successfully employ the CTC dye for imaging and tracking actin proteins by fluorescence microscopy in various in vivo and in vitro systems.


Asunto(s)
Actinas , Colorantes Fluorescentes , Animales , Actinas/metabolismo , Colorantes Fluorescentes/química , Drosophila melanogaster , Cumarinas/química , Línea Celular
3.
Luminescence ; 37(6): 876-882, 2022 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-35305059

RESUMEN

A comparative study of interaction between chicken egg white lysozyme (Lyz) with two hexavalent chromate ions; chromate and dichromate; which are prevalently known for their toxicity, was investigated using different spectroscopic techniques along with a molecular docking study. Both steady-state and time-resolved studies revealed that the addition of chromate/dichromate is responsible for strong quenching of intrinsic fluorescence in Lyz and the quenching is caused by both static and dynamic quenching mechanisms. Different binding and thermodynamic parameters were also calculated at different temperatures from the intrinsic fluorescence of Lyz. The conformational change in Lyz and thermodynamic parameters obtained during the course of interaction with chromate/dichromate were well-supported by the molecular docking results.


Asunto(s)
Cromatos , Muramidasa , Sitios de Unión , Dicroismo Circular , Simulación del Acoplamiento Molecular , Muramidasa/química , Unión Proteica , Espectrometría de Fluorescencia , Termodinámica
4.
Luminescence ; 33(6): 990-998, 2018 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-29927538

RESUMEN

The binding affinity between bovine serum albumin (BSA) and copper ferrite (CuFe2 O4 ) nanoparticles in terms of conformation, stability and activity of protein was studied using various spectroscopic methods. The quenching involved in BSA-CuFe2 O4 NP interaction was static quenching as analysed by different techniques (steady-state and time-resolved fluorescence along with temperature-dependent fluorescence measurements). Among all types of possible interactions, it was revealed that the major binding forces were van der Waals interaction and hydrogen bonding, which were explored from negative values of enthalpy change (∆H = -193.85 kJ mol-1 ) and entropy change (∆S = -588.88 J mol-1  K-1 ). Additionally, synchronous, circular dichroism (CD) and Fourier transform infrared (FTIR) spectroscopy measurements confirmed the conformational changes in BSA upon the addition of CuFe2 O4 NP. Furthermore, thermal denaturation observations were consistent with the circular dichroism results. The interaction of CuFe2 O4 NP with BSA decreased the esterase activity in the BSA assay, revealing the affinity of copper ferrite towards the active site of BSA.


Asunto(s)
Cobre/química , Compuestos Férricos/química , Nanopartículas/química , Albúmina Sérica Bovina/química , Animales , Sitios de Unión , Bovinos , Modelos Moleculares , Tamaño de la Partícula , Conformación Proteica , Albúmina Sérica Bovina/metabolismo , Propiedades de Superficie
5.
Luminescence ; 32(5): 695-705, 2017 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-27808452

RESUMEN

The study of protein-ionic liquid interactions is very important because of the widespread use of ionic liquids as protein stabilizer in the recent years. In this work, the interaction of bovine serum albumin (BSA) with different imidazolium-based ionic liquids (ILs) such as [1-ethyl-3-methyl-imidazolium ethyl sulfate (EmimESO4 ), 1-ethyl-3-methyl-imidazolium chloride (EmimCl) and 1-butyl-3-methyl-imidazolium chloride (BmimCl)] has been investigated using different spectroscopic techniques. The intrinsic fluorescence of BSA is quenched by ILs by the dynamic mechanism. The thermodynamic analysis demonstrates that very weak interactions exist between BSA and ILs. 8-Anilino-1-naphthalenesulfonic acid (ANS) fluorescence and lifetime measurements reveal the formation of the compact structure of BSA in IL medium. The conformational changes of BSA were monitored by CD analysis. Temperature-dependent ultraviolet (UV) measurements were done to study the thermal stability of BSA. The thermal stability of BSA in the presence of ILs follows the trend EmimESO4  > EmimCl > BmimCl and in the presence of more hydrophobic IL, destabilization increases rapidly as a function of concentration.


Asunto(s)
Líquidos Iónicos/química , Albúmina Sérica Bovina/química , Naftalenosulfonatos de Anilina , Dicroismo Circular , Interacciones Hidrofóbicas e Hidrofílicas , Imidazoles , Espectrometría de Fluorescencia , Espectrofotometría Ultravioleta , Termodinámica
6.
J Fluoresc ; 26(5): 1849-55, 2016 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-27422695

RESUMEN

Double-stranded DNA stabilized gold nanoparticles (Au NPs) are synthesized by chemical reduction method and characterized with different spectroscopic techniques such as UV-Visible absorption, Fourier transform infrared (FTIR), & circular-dichroism (CD) as well as transmission electron microscopy (TEM). These NPs show absorption maximum at 520 nm and size of most of the particles are of the order of 3.5 ± 1.0 nm. These Au NPs show crystalline nature as confirmed from electron diffraction pattern. The effect of formation of Au NPs on the macromolecule has been studied using infrared and circular dichroism spectroscopy. Formation of NPs causes conformational changes in the DNA molecules. These Au NPs are further used as resonant energy acceptor of fluorescence emission from dye molecules (Rhodamine 6G). The fluorescence intensity of Rhodamine 6G (R6G) is quenched in presence of Au NPs. The effect of DNA molecules on the fluorescence quenching and the rate of energy transfer from R6G molecules to Au NPs have been explored.

7.
Nanotoxicology ; : 1-19, 2024 Jul 03.
Artículo en Inglés | MEDLINE | ID: mdl-38958196

RESUMEN

Plastic pollution has become a major environmental concern, and various plastic polymers are used daily. A study was conducted to examine the toxic effects of polyethylene terephthalate (PET) nanoplastics (NPLs) on Drosophila melanogaster. We have successfully synthesized PET NPLs and characterized using DLS, Zeta potential, TEM, HRTEM, SAED, XRD, FTIR, and Raman spectroscopy to gain crucial insights into the structure and properties. We fed PET NPLs to Drosophila to assess toxicity. ROS was quantified using DCFH-DA and NBT, and the nuclear degradation was checked by DAPI staining. Quantification of protein and activity of antioxidant enzymes like SOD, catalase depicted the adverse consequences of PET NPLs exposure. The dorsal side of the abdomens, eyes, and wings were also defective when phenotypically analyzed. These results substantiate the genotoxic and cytotoxic impact of nanoplastics. Notably, behavioral observations encompassing larval crawling and climbing of adults exhibit normal patterns, excluding the presence of neurotoxicity. Adult Drosophila showed decreased survivability, and fat accumulation enhanced body weight. These findings contribute to unraveling the intricate mechanisms underlying nanoplastic toxicity and emphasize its potential repercussions for organismal health and ecological equilibrium.

8.
Int J Biol Macromol ; 263(Pt 1): 130128, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38350587

RESUMEN

Bone morphogenetic protein-2 (BMP-2) is a critical growth factor of bone extracellular matrix (ECM), pivotal for osteogenesis. Glycosaminoglycans (GAGs), another vital ECM biomolecules, interact with growth factors, affecting signal transduction. Our study primarily focused on hyaluronic acid (HA), a prevalent GAG, and its sulfated derivative (SHA). We explored their impact on BMP-2's conformation, aggregation, and mechanistic pathways of aggregation using diverse optical and rheological methods. In the presence of HA and SHA, the secondary structure of BMP-2 underwent a structured transformation, characterized by a substantial increase in beta sheet content, and a detrimental alteration, manifesting as a shift towards unstructured content, respectively. Although both HA and SHA induced BMP-2 aggregation, their mechanisms differed. SHA led to rapid amorphous aggregates, while HA promoted amyloid fibrils with a lag phase and sigmoidal kinetics. Aggregate size and shape varied; HA produced larger structures, SHA smaller. Each aggregation type followed distinct pathways influenced by viscosity and excluded volume. Higher viscosity, low diffusivity of protein and higher excluded volume In the presence of HA promotes fibrillation having size in micrometer range. Low viscosity, high diffusivity of protein and lesser excluded volume leads to amorphous aggregate of size in nanometer range.


Asunto(s)
Glicosaminoglicanos , Ácido Hialurónico , Ácido Hialurónico/química , Glicosaminoglicanos/química , Matriz Extracelular/metabolismo , Proteína Morfogenética Ósea 2/metabolismo , Fenómenos Químicos , Osteogénesis
9.
Artículo en Inglés | MEDLINE | ID: mdl-38829386

RESUMEN

Two pyrrolo-based compounds, 1H-pyrrolo[3,2-b]pyridine-3-carboxylic acid (L1) and 1H-pyrrolo[3,2-c]pyridine-4-carboxylic acid (L2), were employed for the detection of bovine serum albumin (BSA) by UV-Vis and fluorescence spectroscopic methods in phosphate buffer solution (pH = 7). In the presence of L1 and L2, the fluorescence emission of BSA at 340 nm was quenched and concomitantly a red-shifted emission band appeared at 420 nm (L1)/450 nm (L2). The fluorescence spectral changes indicate the protein-ligand complex formation between BSA and L1/L2. An isothermal titration calorimetry (ITC) experiment was conducted to determine the binding ability between BSA and L1/L2. The binding constants are found to be 4.45 ± 0.22 × 104 M-1 for L1 and 2.29 ± 0.11 × 104 M-1 for L2, respectively. The thermodynamic parameters were calculated from ITC measurements (i.e. ∆rH = -40 ± 2 kcal/mol, ∆rG = -4.57 ± 0.22 kcal/mol and -T∆rS = 35.4 ± 1.77 kcal/mol), which indicated that the protein-ligand complex formation between L1/L2 with BSA is mainly due to the electrostatic interactions. The protein-ligand interactions were studied by performing molecular docking. Further, the antibacterial assay of L1 and L2 was conducted against gram-positive and gram-negative bacterial strains in an effort to address the difficulties caused by the co-occurrence of antimicrobial and multidrug-resistant bacteria. E. coli and S. aureus were significantly inhibited by L1 and L2. The L1 exhibits 13, 12 and 15 mm, whereas L2 exhibits a 2, 3 and 5 mm zone of inhibition against S. aureus, S. pyogenes and E. coli, respectively. In silico molecular docking of L1 and L2 was performed with bacterial DNA gyrase to establish the intermolecular interactions. Finally, the in vitro cytotoxicity activities of the ligands L1 and L2 have been carried out using drosophila.

10.
J Biomol Struct Dyn ; 41(24): 15435-15445, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36931873

RESUMEN

Nanoparticles (NPs) can directly or indirectly enter into the body because of their small size; then they tend to alter the conformation and function of proteins upon interaction with them. Thus, it is crucial to understand the impact of NPs in a biological medium. Recently, niobium pentoxide nanoparticles (Nb2O5 NPs) are finding increasing applications in the biological system, for example, bone tissue and dental material, matrix for biosensing of proteins, etc. In all such applications, the Nb2O5 NP interacts with proteins and other biomolecules. Hence, the study of such interactions is of considerable importance. Here in this work, we present the impact of Nb2O5 NP on the structure, stability and activity of blood proteins, bovine serum albumin (BSA) and human serum albumin (HSA) by means of various spectroscopic approaches. Steady-state fluorescence studies indicated that intrinsic fluorescence intensities of both serum albumin proteins got quenched upon their interaction with NP. The nature of the quenching was elucidated by time-resolved fluorescence and absorption measurements. Using circular dichroism (CD) and synchronous fluorescence spectroscopy (SFS), the structural perturbations of the protein molecules after interaction with NP were investigated. Moreover, the role of temperature on protein stability upon complexation with NP was also explored. In addition, the effect of NP on protein functionality was probed by esterase-like activity assays.Communicated by Ramaswamy H. Sarma.


Asunto(s)
Nanopartículas , Humanos , Nanopartículas/química , Espectrometría de Fluorescencia , Óxidos , Dicroismo Circular , Albúmina Sérica Bovina/química , Unión Proteica , Termodinámica , Sitios de Unión , Simulación del Acoplamiento Molecular
11.
Chemphyschem ; 12(3): 532-41, 2011 Feb 25.
Artículo en Inglés | MEDLINE | ID: mdl-21308943

RESUMEN

Fluorescence correlation spectroscopy (FCS) and Förster resonance energy transfer (FRET) are both scientific concepts that are frequently discussed in the context of single-molecule fluorescence techniques. In contrast to FCS, FRET is strictly not a technique but a photophysical phenomenon, which can be employed in combination with any method that probes fluorescence intensity or lifetime. Thus, the combination of FCS with FRET is possible and­although these concepts are quite often treated as alternative approaches, particularly for the analysis of biological systems­also quite attractive. However, under certain circumstances, for example, for applications of fluorescence cross-correlation spectroscopy, FRET effects can cause significant complications for quantitative data analysis, and careful calibration has to be carried out to avoid FRET-induced artifacts. This can be most elegantly done if alternating excitation schemes such as PIE (pulsed interleaved excitation) are employed. In this minireview, we discuss the potential and the caveats of FCS combined with FRET and give a short record on successful and promising applications.


Asunto(s)
Transferencia Resonante de Energía de Fluorescencia/métodos , Espectrometría de Fluorescencia/métodos , Algoritmos , Colorantes Fluorescentes/química
12.
Colloids Surf B Biointerfaces ; 202: 111696, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-33770701

RESUMEN

The importance of macromolecules paves the way towards a detailed molecular level investigation as all most all cellular processes occurring at the interior of cells in the form of proteins, enzymes, and other biological molecules are significantly affected because of their crowding. Thus, exploring the role of crowding environment on the denaturation and renaturation kinetics of protein molecules is of great importance. Here, CRABP I (cellular retinoic acid binding protein I) is employed as a model protein along with different molecular weights of Polyethylene glycol (PEG) as molecular crowders. The experimental evaluations are done by accessing the protein secondary structure analysis using circular dichroism (CD) spectroscopy and unfolding kinetics using intrinsic fluorescence of CRABP I at 37 °C to mimic the in vivo crowding environment. The unfolding kinetics results indicated that both PEG 2000 and PEG 4000 act as stabilizers by retarding the unfolding kinetic rates. Both kinetic and stability outcomes presented the importance of crowding environment on stability and kinetics of CRABP I. The molecular dynamics (MD) studies revealed that thirteen PEG 2000 molecules assembled during the 500 ns simulation, which increases the stability and percentage of ß-sheet. The experimental findings are well supported by the molecular dynamics simulation results.


Asunto(s)
Polietilenglicoles , Receptores de Ácido Retinoico , Dicroismo Circular , Cinética , Desnaturalización Proteica , Pliegue de Proteína , Estructura Secundaria de Proteína
13.
Int J Biol Macromol ; 192: 564-573, 2021 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-34653439

RESUMEN

Myoglobin is an essential transport protein of heart and muscle tissues that acts as a local oxygen reservoir and a marker in different diseased conditions. On the other hand, Vitamin B12 is a vital nutrient that helps synthesize red blood cells, DNA, and proteins. To understand the ability of vitamin B12 to bind to the excess of myoglobin produced in the body under certain conditions (muscle injuries, severe trauma, etc.), it is essential to dig into the interaction between them. Therefore, the present study reports the binding interaction of vitamin B12 and myoglobin employing different spectroscopic and computational methods. The myoglobin's intrinsic fluorescence is quenched by vitamin B12 via static nature as observed from steady-state as well as time-resolved fluorescence measurements. The microenvironment of myoglobin's tryptophan residue gets affected, but there is no change observed in its α-helical content by vitamin B12 as seen from synchronous fluorescence and circular dichroism measurements. The probable binding of vitamin B12 on myoglobin was elucidated through molecular docking, and the interaction stability was studied by molecular dynamics simulation. The determination of vitamin B12's affinity to myoglobin and its effect on the conformational transitions of myoglobin might afford valuable insight for clinical pharmacology.


Asunto(s)
Conformación Molecular , Simulación del Acoplamiento Molecular , Simulación de Dinámica Molecular , Mioglobina/química , Vitamina B 12/química , Sitios de Unión , Dicroismo Circular , Humanos , Enlace de Hidrógeno , Unión Proteica , Análisis Espectral
14.
Int J Biol Macromol ; 189: 306-315, 2021 Oct 31.
Artículo en Inglés | MEDLINE | ID: mdl-34419543

RESUMEN

Protein-ligand interactions play a significant role in all living organisms, thereby affecting the design and application of drugs and other biomaterials. The current study reports the binding of vitamin B12 to hemoglobin, employing optical spectroscopy and computational methods. It is observed that vitamin B12 quenched the intrinsic fluorescence of hemoglobin. The nature of quenching appears to be static according to the steady-state and time-resolved fluorescence measurements. The conformational changes of hemoglobin caused by vitamin B12 interactions were studied by synchronous fluorescence spectroscopy and protein secondary structure analyses. The synchronous fluorescence spectra indicate the tryptophan residue microenvironment change while no secondary structural change is observed from circular dichroism spectra and molecular dynamics (MD) simulation study. The computational molecular docking elucidated the probable binding of vitamin B12 at the active site of hemoglobin, whereas the stability of the hemoglobin-vitamin B12 complex was studied by MD simulation. The study might be helpful for the treatment of pernicious anemia, hereditary transcobalamin deficiency, and performance enhancement of elite athletes.


Asunto(s)
Hemoglobinas/química , Simulación de Dinámica Molecular , Vitamina B 12/química , Sitios de Unión , Dicroismo Circular , Hemoglobinas/metabolismo , Humanos , Enlace de Hidrógeno , Cinética , Simulación del Acoplamiento Molecular , Unión Proteica , Conformación Proteica , Estructura Secundaria de Proteína , Espectrometría de Fluorescencia , Espectrofotometría Ultravioleta , Termodinámica , Factores de Tiempo , Vitamina B 12/metabolismo
15.
Int J Biol Macromol ; 182: 2144-2150, 2021 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-34087306

RESUMEN

Glial-cell-line-derived neurotrophic factor (GDNF) is a protein that has therapeutic potential in the treatment of Parkinson's disease and other neurodegenerative diseases. The activity of GDNF is highly dependent on the interaction with sulfated glycans which bind at the N-terminus consisting of 19 residues. Herein, we studied the influence of different glycosaminoglycan (i.e., glycan; GAG) molecules on the conformation of a GDNF-derived peptide (GAG binding motif, sixteen amino acid residues at the N-terminus) using both experimental and theoretical studies. The GAG molecules employed in this study are heparin, heparan sulfate, hyaluronic acid, and sulfated hyaluronic acid. Circular dichroism spectroscopy was employed to detect conformational changes induced by the GAG molecules; molecular dynamics simulation studies were performed to support the experimental results. Our results revealed that the sulfated GAG molecules bind strongly with GDNF peptide and induce alpha-helical structure in the peptide to some extent.


Asunto(s)
Factor Neurotrófico Derivado de la Línea Celular Glial/química , Heparina/farmacología , Heparitina Sulfato/farmacología , Ácido Hialurónico/farmacología , Simulación de Dinámica Molecular , Péptidos/química , Secuencia de Aminoácidos , Dicroismo Circular , Heparina/química , Heparitina Sulfato/química , Ácido Hialurónico/química , Conformación Proteica , Solventes/química , Factores de Tiempo
16.
Spectrochim Acta A Mol Biomol Spectrosc ; 242: 118726, 2020 Dec 05.
Artículo en Inglés | MEDLINE | ID: mdl-32745937

RESUMEN

The impact of glycosaminoglycan (chondroitin sulphate, CS) on bone morphogenetic protein - 2 (BMP - 2) structure, stability (thermal and chemical), association kinetics and conformation was monitored by multiple spectroscopic techniques (UV-Visible, fluorescence and circular dichroism). The absorbance in peptide region and fluorescence intensity of BMP - 2 was quenched in presence of CS; thus, confirming the formation of a ground-state complex. As there was an increase in Stern-Volmer constant observed as a function of temperature, idea of dynamic quenching was established. However, the negligible changes in lifetime indicated static quenching; thus, making the process a combination of static-dynamic quenching. Basically, the protein - glycan interaction was driven by entropy of the system and mediated by hydrophobic interactions. Secondary structure (CD spectroscopy) of native protein was significantly affected (intensity became more negative) in presence of CS, thus, introducing more compactness in the protein. CS infused thermal and chemical stability into BMP - 2 via alteration in its conformation. The rate of association was inversely proportional to concentration of quencher (CS), which confirmed the correlation between large size (~ 5 times the size of protein) and structural complexity of CS with fewer binding sites present in BMP - 2. The rate of association in presence of urea, suggested a decrease in association rate as a function of urea concentration for 15 µM CS. Experimental evidences suggested an interaction between protein and glycan mediated by hydrophobic interactions, which deciphers structural, thermal and chemical stability into protein.


Asunto(s)
Glicosaminoglicanos , Sitios de Unión , Dicroismo Circular , Cinética , Unión Proteica , Estructura Secundaria de Proteína , Espectrometría de Fluorescencia , Termodinámica
17.
Int J Biol Macromol ; 150: 727-736, 2020 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-32061704

RESUMEN

The biophysical aspects of the binding interaction between a phytoestrogen (quercetin, QT) and bone morphogenetic protein - 2 (BMP - 2) was analyzed by various spectroscopic, calorimetric and molecular docking techniques. Interaction studies represented a loss in the absorbance of protein (only the amide region) along with a prominent red shift indicating ground-state complexation which was further confirmed by quenching with significant blue shift observed from steady-state fluorescence measurements. To narrow down the involvement of aromatic residues (Tyr & Trp), synchronous fluorescence spectroscopy was employed. Both Tyr and Trp fluorescence intensity was quenched, however, shifting was noticed only in case of Tyr residues; thus, confirming the alteration in confirmation was mediated upon reduction in polarity around tyrosine residues. It was further validated by quenching studies which highlighted the existence of a buried fraction of fluorophore upon interaction. The nature of fluorescence quenching was static and the binding efficiency was low (binding constant K ~ 10-2 M). Mechanistically, the involvement of van der Waals and hydrogen bonding interaction was confirmed from both van't Hoff plot and molecular docking studies. Secondary structure and thermal stability of the protein was not significantly affected by quercetin. All these investigations confirmed a significant effect on the structure and conformation of BMP - 2 in presence of quercetin which might serve as a potential therapeutic for the treatment of osteoporosis in postmenopausal women.


Asunto(s)
Proteína Morfogenética Ósea 2/química , Simulación del Acoplamiento Molecular , Simulación de Dinámica Molecular , Fitoestrógenos/química , Quercetina/química , Humanos , Unión Proteica
18.
Food Chem ; 312: 126064, 2020 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-31891887

RESUMEN

Biophysical insight into the binding interaction between the major whey protein, ß-Lactoglobulin (ßLG) and vitamin B12, was studied using different spectroscopic tools such as steady-state & time-resolved fluorescence spectroscopy, Circular Dichroism (CD) and Fluorescence Correlation Spectroscopy (FCS). The intrinsic fluorescence of ßLG was quenched by vitamin B12. From the time-resolved fluorescence experiment, the nature of quenching was found to be static suggesting ground-state complex formation between ßLG and vitamin B12, which was also supported by the excitation spectra. Synchronous fluorescence spectra revealed that the tryptophan residue microenvironment of ßLG was affected by the vitamin B12. The CD spectra suggested that the secondary structure of the ßLG remains unaffected by vitamin B12. From the FCS experiment, the tertiary structure of ßLG was observed to be stable in the presence of vitamin B12 at the single-molecule level. The outcome of this study might have potential applications in the food and pharmaceutical industry.


Asunto(s)
Lactoglobulinas/química , Vitamina B 12/química , Fenómenos Biofísicos , Dicroismo Circular , Lactoglobulinas/metabolismo , Estructura Secundaria de Proteína , Espectrometría de Fluorescencia , Triptófano/química , Vitamina B 12/metabolismo
19.
J Biomol Struct Dyn ; 38(7): 2038-2046, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-31282288

RESUMEN

Graphene based materials have attracted global attention due to their excellent properties. GO-metal oxide nanocomposites have been conjugated with biomolecules for the development of novel materials and potentially used as biomarkers. Herein, a detailed study on the interaction of Bovine serum albumin (BSA) with MnO2@RGO (manganese dioxide-reduced graphene oxide) nanocomposites (NC) has been carried out. MnO2@RGO nanocomposites were prepared through a template/surfactant free hydrothermal route at 180 °C for 12 h by varying the graphene oxide (GO) concentration. Different biophysical experiments have been carried out to evaluate molecular interactions between BSA and NCs. Intrinsic fluorescence has been used to quantify the quenching efficiency of NCs and the binding association of BSA-NC complexes. NCs effectively quenched the intrinsic fluorescence of BSA via static and dynamic mechanism. Further, the results indicate that the molecular interactions of NC with BSA are dependent on the GO percentage in NC. Circular dichroism results demonstrate nominal changes in the secondary structure of BSA in presence of NCs. Also, the esterase-like activity of BSA was marginally affected after adsorption upon NCs. In addition, the FESEM micrographs reveal that the protein-NC complexes consist of nanorod and sheet-like morphologies are forming aggregates of different sizes. We hope that this study will provide a basis for the design of novel graphene based and other related nanomaterials for several biological applications.Communicated by Ramaswamy H. Sarma.


Asunto(s)
Grafito , Nanocompuestos , Compuestos de Manganeso , Óxidos , Albúmina Sérica Bovina
20.
Int J Biol Macromol ; 165(Pt A): 333-345, 2020 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-32980413

RESUMEN

The current study aims to check various behavioural, developmental, cytotoxic, and genotoxic effects of Fe3O4-GG nanocomposite (GGNCs) on Drosophila melanogaster. Fe3O4 nanoparticles were prepared by the chemical co-precipitation method and cross-linked with guargum nanoparticles to prepare the nanocomposites. The nanocomposites were characterized by using transmission electron microscopy (TEM), X-ray diffraction (XRD), and FTIR techniques. To investigate the biomolecular interaction, GGNCs was further tagged with Fluorescein isothiocyanate. Various concentrations of nanocomposites were mixed with the food and flies were allowed to complete the life cycle. The life cycle of the flies was studied as a function of various concentrations of GGNCs. The 1st instar larvae after hatching from the egg start eating the food mixed with GGNCs. The 3rd instar larvae were investigated for various behavioural and morphological abnormalities within the gut. The 3rd instar larva has defective crawling speed, crawling path, and more number of micronuclei within the gut. Similarly, in adult flies thermal sensitivity, climbing behaviour was found to be altered. In adult flies, a significant reduction in body weight was found which is further correlated with variation of protein, carbohydrate, triglyceride, and antioxidant enzymes. Altogether, the current study suggests GGNCs as a non-genotoxic nanoparticle for various biological applications.


Asunto(s)
Materiales Biocompatibles Revestidos , Daño del ADN , Óxido Ferrosoférrico , Galactanos , Mananos , Gomas de Plantas , Animales , Materiales Biocompatibles Revestidos/química , Materiales Biocompatibles Revestidos/farmacología , Drosophila melanogaster , Óxido Ferrosoférrico/química , Óxido Ferrosoférrico/farmacología , Galactanos/química , Galactanos/farmacología , Larva/crecimiento & desarrollo , Mananos/química , Mananos/farmacología , Gomas de Plantas/química , Gomas de Plantas/farmacología
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