Arjama Kundu

Binding interaction of an anionic amino acid surfactant with bovine serum albumin: physicochemical and spectroscopic investigations combined with molecular docking study

The interaction of a synthesised amino acid surfactant, sodium-N-dodecanoylphenylalaninate (AAS) with a transport protein, bovine serum albumin (BSA) has been uncovered employing various physicochemical and spectroscopic techniques like tensiometry, electro kinetic potential measurements, steady-state fluorometry, time-resolved measurements and circular dichroism (CD) at physiological pH and 298 K. The difference in tensiometric responses of AAS in the absence and presence of BSA indicates a significant interaction operative between them. The zeta (ξ) potential measurements have been taken into account in assigning the type of binding interaction between them. The steady-state fluorescence study reveals the sequential unfolding of BSA with stepwise addition of AAS. Stern–Volmer and modified Stern–Volmer plots, Scatchard plots and thermodynamic parameters have been employed to find the type of binding of AAS to BSA. Life-time measurements have been carried out to shed light on the relative amplitude of binding of AAS to the two Trp residues of BSA namely Trp-134 and Trp-213. The changes in protein secondary structure induced by AAS are unveiled by CD measurements. Quantum mechanical calculations involving density functional theory (DFT) and molecular docking analysis have been undertaken to highlight the interactive phenomenon between the two. Thus this work shows a total inspection of an amino acid surfactant–BSA interaction.

Binding affinities of Schiff base Fe(II) complex with BSA and calf-thymus DNA: Spectroscopic investigations and molecular docking analysis.

The binding interaction of a synthesized Schiff base Fe(II) complex with biological macromolecules viz., bovine serum albumin (BSA) and calf thymus(ct)-DNA have been investigated using different spectroscopic techniques coupled with viscosity measurements at physiological pH and 298K. Regular amendments in emission intensities of BSA upon the action of the complex indicate significant interaction between them, and the binding interaction have been characterized by Stern Volmer plots and thermodynamic binding parameters. On the basis of this quenching technique one binding site with binding constant (Kb=(7.6±0.21)×10(5)) between complex and protein have been obtained at 298K. Time-resolved fluorescence studies have also been encountered to understand the mechanism of quenching induced by the complex. Binding affinities of the complex to the fluorophores of BSA namely tryptophan (Trp) and tyrosine (Tyr) have been judged by synchronous fluorescence studies. Secondary structural changes of BSA rooted by the complex has been revealed by CD spectra. On the other hand, hypochromicity of absorption spectra of the complex with the addition of ct-DNA and the gradual reduction in emission intensities of ethidium bromide bound ct-DNA in presence of the complex indicate noticeable interaction between ct-DNA and the complex with the binding constant (4.2±0.11)×10(6)M(-1). Life-time measurements have been studied to determine the relative amplitude of binding of the complex to ct-DNA base pairs. Mode of binding interaction of the complex with ct-DNA has been deciphered by viscosity measurements. CD spectra have also been used to understand the changes in ct-DNA structure upon binding with the metal complex. Density functional theory (DFT) and molecular docking analysis have been employed in highlighting the interactive phenomenon and binding location of the complex with the macromolecules.

Kinetic investigation on the oxidation of tris(1,10-phenanthroline)iron(II) by oxone: the effect of BSA-SDS interaction.

The kinetic investigations of oxidation of tris(1,10-phenanthroline)iron(II) by oxone have been studied spectrophotometrically in phosphate buffer medium of pH 6.8, temperature 308 K, and ionic strength 0.25 mol L(-1). The reactions were also carried out in presence of globular transport protein, bovine serum albumin (BSA) having isoelectric point 4.9, anionic surfactant sodium dodecyl sulfate (SDS), and their mixtures. The critical aggregation concentration (CAC) and critical micelle concentration (CMC) of SDS in presence of BSA have been determined using conductivity and kinetic measurement techniques. The secondary structure of BSA was examined by Circular Dichroism (CD) measurement at 308 K. The helix nature of BSA decreases with increase of SDS concentration. The effect of pH on rate in presence of BSA is opposite to its absence, and the effect of urea on rate in presence of BSA indicates the denaturation of BSA. The results depict that amphiphile SDS interacts with BSA and different molecular events, for example, specific binding, cooperative binding, protein unfolding, and micelle formation act. Activation parameters of the reaction in different environments have been determined.

Kinetic exploration supplemented by spectroscopic and molecular docking analysis in search of the optimal conditions for effective degradation of malachite green

The degradation of malachite green (MG) by an alkaline hydrolytic process has been explored spectrophotometrically. The kinetics of the reaction have been meticulously studied under the influence of cationic alkyltrimethylammonium bromide (DTAB, TTAB and CTAB) surfactants, α-, β- and γ-cyclodextrins (CDs) and surfactant–β-CD mixed systems applying pseudo-first order conditions at 298 K. The surfactants and cyclodextrins individually catalyze the hydrolytic rate, whereas surfactant–β-CD mixed systems exhibit both an inhibiting and catalytic influence depending on the surfactant concentrations. The kinetic results have been explained precisely based on the pseudo-phase ion exchange (PIE) model of micelles and CD-catalyzed model of CD systems. The surfactants exhibit micellar surface catalysis, while CDs accelerate the rate by forming MG–CD inclusion complexes, thereby facilitating nucleophilic attack of its ionized secondary hydroxyl group on the carbocation center of MG. The encapsulation of MG within the supramolecular host cavity of the CDs has been investigated diligently using a steady-state absorption spectroscopic technique. The result shows 1 : 1 host–guest complexation with different relative orientations of the guest (MG) inside the hosts. Studies employing density functional theory (DFT) as well as molecular docking analysis provide valuable insight on the insertion mechanism. The results reveal that quantitative analysis can be utilized to predict the optimum conditions for the fastest degradation of MG in ambient environments.