Spectrochimica Acta Part A- Molecular and Biomolecular Spectroscopy (original) (raw)
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BioNanoScience, 2019
Benzocaine drug (BZC) is an active component of various nonprescription drugs and used for numb teething treatments. The interaction of BZC with bovine serum albumin (BSA) has been studied using fluorescence, synchronous fluorescence, UV-Vis, circular dichroism (CD), and molecular docking analysis. The results revealed that BZC has a strong affinity to quench the intrinsic fluorescence of BSA in terms of a static quenching mechanism under physiological conditions. The fluorescence quenching data revealed that the quenching constants are (K SV) 4.10, 3.30, and 2.35 × 10 4 L mol −1 at 298, 304, and 310 K, respectively. The binding constants (K b) at three different temperatures (298, 304, and 310 K) were found to be 6.02, 3.72, and 1.10 × 10 5 L mol −1 , respectively. The thermodynamic parameters ΔH°and ΔS°have been estimated to be − 70.67 and − 128.9 J mol −1 K −1 , respectively, thereby, indicating that hydrogen bonding and Van der Waals forces play major role in the interaction of BSA-BZC. Moreover, the negative values of ΔG°− 32.30, − 31.50, − 30.68 kJ mol −1 at 298, 304, 310 K, respectively, indicate the spontaneity of the interaction. FRET analysis proved high probability of energy transfer from BSA to the drug molecule. Molecular docking and displacement studies indicated that BZC was bound to the Sudlow's site II through hydrogen bonding and Van der Waals interactions.
The Journal of Physical Chemistry B
This work aimed to investigate the interaction of bovine serum albumin with newly synthesized potent new pyrene derivatives (PS1 and PS2), which might prove useful to have a better antibacterial character as found for similar compounds in the previous report [Low et al. Bioconjugate Chemistry 2014, 12, 2269−2284]. However, to date, binding studies with plasma protein are still unknown. Steady-state fluorescence spectroscopy and lifetime fluorescence studies show that the static interaction binding mode and binding constants of PS1 and PS2 are 7.39 and 7.81 [K b × 10 5 (M −1)], respectively. The experimental results suggest that hydrophobic forces play a crucial role in interacting pyrene derivatives with BSA protein. To verify this, molecular docking and molecular dynamics simulations were performed to predict the nature of the interaction and the dynamic behavior of the two compounds in the BSA complex, PS1 and PS2, under physiological conditions of pH = 7.1. In addition, the free energies of binding for the BSA-PS1 and BSA-PS2 complexes were estimated at 300 K based on the molecular mechanics of the Poisson− Boltzmann surface (MMPBSA) with the Gromacs package. PS2 was found to have a higher binding affinity than PS1. To determine the behavior of the orbital transitions in the ground state geometry, we found that both compounds have similar orbital transitions from HOMO−LUMO via π → π* and HOMO−1−LUMO+1 via n → π*, which was included in the FMO analysis. A cytotoxicity study was performed to determine the toxicity of the compounds. Based on the MD study, the stability of the compounds with BSA and the dynamic binding modes were further revealed, as well as the nature of the binding force components involved and the important residues involved in the binding process. From the binding energy analysis, it can be assumed that PS2 may be more active than PS1.
Biomolecules, 2022
Benzofuran derivatives are synthetic compounds that are finding an increasing interest in the scientific community not only as building blocks for the realization of new materials, but also as potential drugs thanks to their ability to interact with nucleic acids, interfere with the amyloid peptide aggregation and cancer cell cycle. However, their ability to interact with proteins is a theme still in need of investigation for the therapeutic importance that benzofurans could have in the modulation of protein-driven processes and for the possibility of making use of serum albumins as benzofurans delivery systems. To this scope, we investigated the protein binding ability of two 4-nitrophenyl-functionalized benzofurans previously synthesized in our laboratory and herein indicated as BF1 and BDF1, which differed for the number of furan rings (a single moiety in BF1, two in BDF1), using bovine serum albumin (BSA) as a model protein. By circular dichroism (CD) spectroscopy we demonstrate...
Binding interaction of 1-(4-methybenzyl)-2-p-tolyl-1H-benzo[d]imidazole with bovine serum albumin
A promising benzimidazole derivative 1-(4-methybenzyl)-2-p-tolyl-1H-benzo[d]imidazole (MBTBI) has been synthesized and characterized by single crystal XRD, NMR, mass and IR spectral techniques. The mutual interaction of this benzimidazole derivative (MBTBI) with bovine serum albumin (BSA) was investigated using solution spectral studies. The fluorescence quenching mechanism of BSA by MBTBI was analyzed and the binding constant has been calculated. The binding distance between these two was obtained based on the theory of Forester's non-radiation energy transfer (FRET). The effect of some common ions on the binding constant was also examined.
Molecules
The lipophilic derivative of thalidomide (4-(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)-N-[(4-ethoxyphenyl)methylidene]benzohydrazide, 6P) was synthesized to enhance its characteristics and efficacy. Earlier studies have proved the immunomodulatory and anti-inflammatory effects of 6P. In this study the interaction between bovine serum albumin (BSA) and 6P was studied using a multi-spectroscopic approach which included UV spectrophotometry, spectrofluorimetry and three dimensional spectrofluorometric and molecular docking studies. Static quenching was involved in quenching the fluorescence of BSA by 6P, because a complex formation occurred between the 6P and BSA. The binding constant decreased with higher temperature and was in the range of 2.5 × 10 5-4.8 × 10 3 L mol −1 suggesting an unstable complex at higher temperatures. A single binding site was observed and the the site probe experiments showed site II (sub-domain IIIA) of BSA as the binding site for 6P. The negative values of ∆G 0 , ∆H 0 and ∆S 0 at (298/303/308 K) indicated spontaneous binding between 6P and BSA as well as the interaction was enthalpy driven and van der Waals forces and hydrogen bonding were involved in the interaction. The docking results and the results from the experimental studies are complimentary to each other and confirm that 6P binds at site II (sub-domain IIIA) of BSA.
Luminescence, 2017
Chalcones possess various biological properties, for example, antimicrobial, anti-inflammatory, analgesic, antimalarial, anticancer, antiprotozoal and antitubercular activity. In this study, naphthylchalcone derivatives were synthesized and characterized using 1 H NMR 13 C NMR, Fou-rier transform infrared and mass techniques. Yields for all derivatives were found to be >90%. Protein-drug interactions influence the absorption, distribution, metabolism and excretion (ADME) properties of a drug. Therefore, to establish whether the synthesized naphthylchalcone derivatives can be used as drugs, their binding interaction toward a serum protein (bovine serum albumin) was investigated using fluorescence, circular dichroism and molecular docking techniques under physiological conditions. Fluorescence quenching of the protein in the presence of naphthylchalcone derivatives, and other derived parameters such as association constants, number of binding sites and static quenching involving confirmed non-covalent binding interactions in the protein-ligand complex were observed. Circular dichroism clearly showed changes in the secondary structure of the protein in the presence of naphthylchalcones, indicating binding between the derivatives and the serum protein. Molecular modelling further confirmed the binding mode of naphthylchalcone derivatives in bovine serum albumin. A site-specific molecular docking study of naphthylchalcone derivatives with serum albumin showed that binding took place primarily in the aromatic low helix and then in subdomain II. The dominance of hydrophobic, hydrophilic and hydrogen bonding was clearly visible and was responsible for stabilization of the complex.
2009
Binding of a newly synthesized indanedione derivative, 2-(2-hydroxy-3ethoxybenzylidene)-1,3-indanedione (HEBID), to human and bovine serum albumins (HSA and BSA), under simulated physiological conditions was monitored by fluorescence spectroscopy. The binding parameters (binding constants and number of binding sites) and quenching constants were determined according to literature models. The quenching mechanism was assigned to a Förster non-radiative energy transfer due to the HEBID-SA complex formation. A slightly increased affinity of HEBID for HSA was found, while the number of binding sites is approximately one for both albumins. The molecular distance between donor (albumin) and acceptor (HEBID) and the energy transfer efficiency were estimated, in the view of Förster's theory. The effect of HEBID on the protein conformation was investigated using circular dichroism and synchronous fluorescence spectroscopies. The results revealed partial unfolding in the albumins upon interaction, as well as changes in the local polarity around the tryptophan residues.
Molecular Probes for Biomedical Applications II, 2008
2-pyridone (2Py) and 3-pyridone (3Py) were examined in different solvents and their binding to human serum albumin (HSA) was studied using steady-state spectroscopy and time-resolved fluorescence. Solvation of 2Py and 3Py by water was examined in binary mixtures of 1,4-dioxane and water. Analysis of the absorption and fluorescence data reveals the solvation of the hydrogen bonding center in 2Py by one water molecule and in 3Py by three water molecules. A zwitterionic tautomer of 3Py is formed in water and shows distinct absorption peaks from the absorption of the neutral tautomer. Fluorescence of 3Py was observed in polar solvents only, whereas 2Py is fluorescent in polar and nonpolar solvents. The absorption and fluorescence spectra of 2Py in different solvents indicate less solute-solvent interaction in nonpolar solvents. This observation was confirmed by the measured longer fluorescence lifetime of 2Py in cyclohexane compared to that in water. The mechanism of binding of 2Py and 3Py as probe ligands to HSA was investigated by following the intensity change and lifetime of HSA fluorescence after excitation at 280 nm. The presence of 2Py and 3Py causes a reduction in the fluorescence intensity and lifetime of HSA. This observation indicates that subdomain IIA binding site (Sudlow site I) is the host of the probes and the reduction in the fluorescence of HSA is due to energy transfer from the Trp-214 residue to the probe in each case. The distance between Trp-214 and each of the probes was calculated using Förster theory for energy transfer to be 1.99 nm for HSA/2Py and 2.44 nm for HSA/3Py. The shorter distance in the former complex indicates more efficient energy transfer than in the latter. This was confirmed by estimating the quenching rate constant (k q ) in each complex. k q was calculated to be 1.44 x 10 12 M -1 s -1 for HSA/2Py and 3.45 x 10 11 M -1 s -1 for HSA/3Py. The calculated distances and the k q values indicate a static quenching mechanism operative in the two complexes. The binding constants were estimated to be K = (3.4 ± 0.4) x 10 4 M -1 for the HSA/2Py complex and K = (2.3 ± 0.3) x 10 4 M -1 for the HSA/3Py complex. The number of binding sites of HSA was calculated to be one in both complexes. The latter results, along with the quenching results, indicate that both probes, 2Py and 3Py, bind only in Sudlow site I in subdomain IIA.