Exploration of pH-Dependent Behavior of the Anion Receptor Pocket of Subdomain IIA of HSA: Determination of Effective Pocket Charge Using the Debye–Hückel Limiting Law

Delineating the cascade of molecular events in protein aggregation triggered by Glyphosate, aminomethylphosphonic acid, and Roundup in serum albumins

The molecular basis of protein unfolding on exposure to the widely used herbicide, Glyphosate (GLY), its metabolite aminomethylphosphonic acid (AMPA), and the commercial formulation Roundup have been probed using human and bovine serum albumins (HSA and BSA). Protein solutions were exposed to chemical stress at set experimental conditions. The study proceeds with spectroscopic and imaging tools. Steady-state and time-resolved fluorescence (TRF) measurements indicated polarity changes with the possibility of forming a ground-state complex. Atomic force microscopy imaging results revealed the formation of fibrils from BSA and dimer, trimer, and tetramer forms of oligomers from HSA under the chemical stress of GLY. In the presence of AMPA, serum albumins (SAs) form a compact network of oligomers. The compact network of oligomers was transformed into fibrils for HSA with increasing concentrations of AMPA. In contrast, Roundup triggered the formation of amorphous aggregates from SAs. Analysis of the Raman amide I band of all aggregates showed a significant increase in antiparallel β-sheet fractions at the expense of α-helix. The highest percentage, 24.6%, of antiparallel β-sheet fractions was present in amorphous aggregate formed from HSA under the influence of Roundup. These results demonstrated protein unfolding, which led to the formation of oligomers and fibrils.

Non-enzymatic electrochemical glucose sensing by Cu2O octahedrons: elucidating the protein adsorption signature

Developing an electrochemical biosensor based on Cu₂O octahedrons for rapid, sensitive and highly selective detection of glucose in real samples with an unprecedented analysis of their protein adsorption signature.

Insights into the binding mechanism of BODIPY-based photosensitizers to human serum albumin: A combined experimental and computational study

Photodynamic therapy (PDT) is a noninvasive and effective approach in clinical cancer treatments. Boron-dipyrromethene (BODIPY)-based derivatives have emerged as novel and promising photosensitizers (PSs) in PDT, attributed to their strong near-infrared singlet oxygen luminescence emissions and high photostabilities. However, the binding mechanism of BODIPY derivatives to proteins, key for their therapeutic and biomedical applications is still poorly understood. Here, we investigated the molecular interactions of two 2, 6-diiodo-BODIPY derivatives with human serum albumin (HSA) using combined experimental and computational techniques. Our spectroscopic results showed that both BODIPY derivatives formed stable complexes with HSA. Strikingly, the BODIPY/HSA complexes exhibited notably enhanced water solubility and singlet oxygen generation efficiency with respect to the BODIPY alone. Furthermore, molecular docking, molecular dynamics simulations, and binding free energy calculations provided the structural and energetic insights into the binding mechanism of BODIPY-based derivatives to HSA. Our work demonstrated that conjugation of BODIPYs with HSA may be a promising strategy to enhance the performance of BODIPY-based PSs, and the combination of computational and experimental techniques is expected to play key roles in the design and development of novel PSs with improved bioavailability and biocompatibility for cancer therapeutic applications.

Interactions of two food colourants with BSA: Analysis by Debye-Hückel theory

We have focused on exploring pH- and ionic strength-modulated binding of acid red 1 (AR1) and acid green 50 (AG50) with bovine serum albumin (BSA) by fluorescence, UV-vis absorption and FTIR spectra. The results implied that the quenching mechanism of BSA-AR1/AG50 system was a static quenching, electrostatic force dominated the formation of BSA-AR1/AG50 complex, and the binding affinity of AR1 was greater than that of AG50 on the subdomain IIA of BSA. Moreover, their true thermodynamic binding constant (Keq), true free energy change (ΔG(0)I→0), and effective charge (ZP) in the anion receptor pocket of BSA were calculated using Debye-Hückel limiting law. The local charge bound by AR1/AG50 rather than the overall or surface charge of BSA played a key role in determining their interaction strength. Besides, the thermal and structural stabilization of BSA was discussed by analyzing the changes of Tm and Hurea without/with the addition of AR1/AG50, respectively.

Data of fluorescence, UV-vis absorption and FTIR spectra for the study of interaction between two food colourants and BSA

In this data article, the fluorescence, UV–vis absorption and FTIR spectra data of BSA-AR1/AG50 system were presented, which were used for obtaining the binding characterization (such as binding constant, binding distance, binding site, thermodynamics, and structural stability of protein) between BSA and AR1/AG50.

Distilbene derivative as a new environment-sensitive bifunctional ligand for the possible induction of serum protein aggregation: a spectroscopic investigation and potential consequences

The photophysical properties of a new distilbene fluorophore, DPDB, belonging to the conjugated polyene family is found to be well modulated with the variation of the microenvironment. Compared to the ground state, the excited-state photophysical properties of the fluorophore have been altered to larger extents with the variation of polarity and the hydrogen-bonding nature of solvents. The change in the fluorescence intensity of DPDB shows a nice correlation with the aggregation behavior of different surfactants which have been utilized for the determination of the CMC of surfactants. The distribution of DPDB is found to be higher in nonionic micelles. On the other hand, DPDB specifically binds the subdomain IB cavity of serum albumin with a stronger binding ability with HSA compared to BSA. DPDB behaves like a bivalent (bifunctional) ligand and forms a complex of 2:1 stoichiometry with serum albumins. Dynamic light scattering and circular dichroism measurements indicate that DPDB favors the association of serum albumin molecules, promoting their preaggregation state. Aggregation is an important phenomenon and is known to be initiated by heat, extreme pH conditions, very high ionic strength, surfactants, metal ions, and so forth. This study explores a new avenue in bringing about association phenomena of serum albumins and points out that the binding of such a bifunctional ligand may also become an important factor in inducing the protein association.

Ultrafast dynamics of a molecular rotor in chemical and biological nano-cavities

Excited state dynamics of CCVJ are investigated inside the nano-cavities of CD and HSA using steady-state and femtosecond up-conversion techniques.