Monitoring the interactions between bovine serum albumin and ZnO/Ag nanoparticles by spectroscopic techniques.

Inducing the bio-functionalization in noble metal nanoparticles like gold, silver, zinc is very important to accomplish their biocompatibility in biological activities. These metal nanoparticles are being rigorously used in bio-sensing tools keeping their remarkable properties in mind. Amongst the serum albumins, the most ample proteins in plasma are bovine serum albumin and human serum albumin. A broad variety of physiological functions of bovine serum albumin has made it a model protein for bio-functionalization. In the present study, ZnO/Ag nanoparticles were synthesized and characterized by SEM and XRD techniques and the interaction between bovine serum albumin and ZnO/Ag nanoparticles was evaluated by employing ultra-violet, steady state fluorescence, circular dichroism and FTIR spectroscopic techniques. Upon the excitation of bovine serum albumin, ZnO/Ag nanoparticles appreciably reduced the intrinsic fluorescence intensity of bovine serum albumin. The number of binding locations and apparent binding constants at different temperatures were calculated by the fluorescence quenching method. Static mechanism of quenching and conformational modifications in bovine serum albumin were also found.Communicated by Ramaswamy H. Sarma.

Molecular spectroscopic and docking analysis of the interaction of fluorescent thiadicarbocyanine dye with biomolecule bovine serum albumin.

Binding studies of the water-soluble thiadicarbocyanine dye 3,3'-diethylthiadicarbocyanine acetate (DTC) with bovine serum albumin (BSA) were examined under physiological conditions using spectroscopic techniques like fluorescence, UV-Visible, circular dichroism (CD), FT-IR and molecular docking methods. Compiled experimental results envisage that DTC quench the fluorescence intensity of BSA. The increasing binding constants (K) were found to be in the order of 103 Mol-1 as a function of temperature, as calculated from the fluorescence quenching data. The quenching mechanism, thermodynamic parameters (ΔH0, ΔS0 and ΔG0) and the number of binding sites have been explored. CD values showed that the secondary structure of the BSA has been altered upon binding to DTC. Displacement experiments were carried out with different site probes to find out the binding site of DTC on BSA and it was found that binding interaction at site II of sub-domain IIIA. The interference of common metal ions on the interaction of DTC with BSA has also been studied. The experimental data exhibit that DTC interacts with BSA by hydrophobic forces. The experimental findings from BSA binding studies were validated by using in silico molecular docking technique. The results of the investigations were accurately supported by studies on molecular docking. The optimal shape of the molecular probe demonstrated the affinity as a free binding energy release of -7.37 Kcal/mol. The present research report endeavors to the approachable nature of water-soluble DTC dye and paves way for targeted biological interactions.Communicated by Ramaswamy H. Sarma.

BSA binding and antibacterial studies of newly synthesized 5,6-Dihydroimidazo[2,1-b]thiazole-2-carbaldehyde.

A new heterocyclic compound, 5,6-Dihydroimidazo[2,1-b]thiazole-2-carbaldehyde (ITC) was synthesized and its antibacterial activity and also its interaction with bovine serum albumin (BSA) were studied. The structure of the synthesized compound was confirmed by 1H NMR, 13C NMR and IR spectroscopic techniques. The antibacterial activity was carried out by minimum inhibitory concentration (MIC) method. The compound showed a good antibacterial activity. The mechanism of interaction between the BSA and ITC under physiological conditions was investigated by various molecular spectroscopic techniques like, fluorescence, circular dichroism (CD), UV absorption and FT-IR. The interaction between ITC and BSA was followed by studying the quenching of intrinsic fluorescence of BSA upon the addition of ITC at three different temperatures. The binding constant (K), Stern-Volmer quenching constant (Ksv) and number of binding sites were determined. The separation distance between BSA and ITC was evaluated based on the fluorescence resonance energy transfer theory. The conformational changes in BSA upon binding of ITC were also confirmed. The interference of some metal ions on interaction was studies. The displacement studies with site specific markers confirm that the site III was the binding site for ITC on BSA.

Synthesis, crystal studies, anti-tuberculosis and cytotoxic studies of 1-[(2E)-3-phenylprop-2-enoyl]-1H-benzimidazole derivatives.

Series of 1-[(2E)-3-phenylprop-2-enoyl]-1H-benzimidazole derivatives were synthesized and characterized by spectral methods. Among 21 derivatives, single crystals of 3a and 3l were grown and their structural parameters were evaluated. Newly synthesized compounds were screened for anti-tubercular activity and the MIC was determined against Mycobacterium tuberculosis H37Rv by Microplate Alamar Blue Assay (MABA) method. Majority of the compounds exhibited a promising inhibition of M. tuberculosis and the molecules functionalized with electron-donating groups at C-2 carbon of benzimidazole moiety were found to be more active in inhibiting M. tuberculosis. Further, more promising compounds viz., 3b, 3i and 3l were tested for their cytotoxic activity. Compound 3l was found to display excellent activity (IC50 < 10 µg mL(-1)) with 100% cell lysis at 30 µg mL(-1) concentration against A549 (Human lung carcinoma) and 8E5 (Human; Acute Lymphoblastic Leukemia) cell lines.

The effect of anti-tubercular drug, ethionamide on the secondary structure of serum albumins: a biophysical study.

Serum albumin (SA) is the principal extra cellular protein with higher concentration in the blood plasma and acts as a carrier for many drugs to different molecular targets. The present work is designed to investigate the mechanism of interaction between the protein and an anti-tubercular drug, ethionamide (ETH) at the physiological pH by different molecular spectroscopic techniques viz., fluorescence, UV absorption, CD and FTIR. The interaction of SA with ETH was studied by following the quenching of intrinsic fluorescence of protein by ETH at different temperatures. The Stern-Volmer quenching constant, binding constant and the binding site numbers were calculated from fluorescence results. The results indicated the presence of static quenching mechanism in both HSA-ETH and BSA-ETH systems. The distances of separation between the acceptor and donor were calculated based on the theory of fluorescence resonance energy transfer and were found to be 2.35 nm and 2.18 nm for HSA-ETH and BSA-ETH systems, respectively. The conformational changes in protein were confirmed from UV absorption, CD and FTIR spectral data. Displacement experiments with different site probes revealed that the site I was the main binding site for ETH in protein. Effect of some metal ions was also investigated.

Interaction of triprolidine hydrochloride with serum albumins: thermodynamic and binding characteristics, and influence of site probes.

The interaction between triprolidine hydrochloride (TRP) to serum albumins viz. bovine serum albumin (BSA) and human serum albumin (HSA) has been studied by spectroscopic methods. The experimental results revealed the static quenching mechanism in the interaction of TRP with protein. The number of binding sites close to unity for both TRP-BSA and TRP-HSA indicated the presence of single class of binding site for the drug in protein. The binding constant values of TRP-BSA and TRP-HSA were observed to be 4.75 ± 0.018 × 10(3) and 2.42 ± 0.024 × 10(4)M(-1) at 294 K, respectively. Thermodynamic parameters indicated that the hydrogen bond and van der Waals forces played the major role in the binding of TRP to proteins. The distance of separation between the serum albumin and TRP was obtained from the Förster's theory of non-radioactive energy transfer. The metal ions viz., K(+), Ca(2+), Co(2+), Cu(2+), Ni(2+), Mn(2+) and Zn(2+) were found to influence the binding of the drug to protein. Displacement experiments indicated the binding of TRP to Sudlow's site I on both BSA and HSA. The CD, 3D fluorescence spectra and FT-IR spectral results revealed the changes in the secondary structure of protein upon interaction with TRP.

Interaction of bioactive coomassie brilliant blue g with protein: insights from spectroscopic methods.

The binding of coomassie brilliant blue G (CBB) to bovine serum albumin (BSA) was investigated under simulative physiological conditions employing different optical spectroscopic techniques viz., fluorescence emission, UVâvisible absorption and FTIR. Fluorescence quenching data obtained at different temperatures suggested the presence of dynamic type of quenching mechanism. The binding constant of CBB-BSA and the number of binding sites (n) for CBB in BSA were calculated and found to be 4.20 Ã 10(4) M(â1) and 0.96 respectively, at 302 K. The value of n close to unity indicated that the protein has a single class of binding sites for CBB. The thermodynamic parameters revealed that the hydrophobic forces played a major role in the interaction of CBB to BSA. The distance between the CBB and protein was calculated using the theory of FÃsterâs Resonance Energy Transfer (FRET). The conformational change in the secondary structure of BSA upon interaction with dye was investigated by synchronous fluorescence and FTIR techniques. Competitive binding studies were also carried out to know the location of binding of CBB on BSA.

Probing the binding of fluoxetine hydrochloride to human serum albumin by multispectroscopic techniques.

The interaction between human serum albumin (HSA) and fluoxetine hydrochloride (FLX) have been studied by using different spectroscopic techniques viz., fluorescence, UV-vis absorption, circular dichroism and FTIR under simulated physiological conditions. Fluorescence results revealed the presence of static type of quenching mechanism in the binding of FLX to HSA. The values of binding constant, K of FLX-HSA were evaluated at 289, 300 and 310 K and were found to be 1.90x10(3), 1.68x10(3) and 1.45x10(3) M(-1), respectively. The number of binding sites, n was noticed to be almost equal to unity thereby indicating the presence of a single class of binding site for FLX on HSA. Based on the thermodynamic parameters, DeltaH(0) and DeltaS(0) nature of binding forces operating between HSA and FLX were proposed. Spectral results revealed the conformational changes in protein upon interaction. Displacement studies indicated the site I as the main binding site for FLX on HSA. The effect of common ions on the binding of FLX to HSA was also investigated.

Voltammetric and spectroscopic investigations on the mechanism of interaction of buzepide methiodide with protein.

Adsorption or immobilization of proteins on solid surfaces promotes the biological responses to materials. Using immobilization technique, we have prepared human serum albumin (HSA) modified glassy carbon electrode (GCE) and employed it to probe the mode of interaction between antidepressant drug, buzepide methiodide (BZP) and HSA. At HSA modified GCE, the peak potential of BZP appeared at more positive potential compared to that at bare electrode thereby indicating the hydrophobic mode of interaction between BZP and HSA. Peak currents of BZP decreased upon the addition of HSA at bare GCE with positive shift in peak potential. Further, no new peaks were observed in presence of HSA. From electrochemical data, the binding constant and binding ratio between HSA and BZP were calculated to be 9.33 x 10(6)M(-1) and 1:2, respectively. FT-IR and circular dichroism (CD) studies revealed that the secondary structure of protein was perturbed upon interaction with BZP.