Fluorescence Study on the Interaction of Bovine Serum Albumin with P-Aminoazobenzene

Abstract

In this paper, the interaction between p-aminoazobenzene (PAAB) and BSA was investigated mainly by fluorescence quenching spectra, circular dichroism (CD) and three-dimensional fluorescence spectra under simulative physiological conditions. It was proved that the fluorescence quenching of BSA by PAAB was mainly a result of the formation of a PAAB-BSA complex. The modified Stern-Volmer quenching constant K(a) and the corresponding thermodynamic parameters DeltaH, DeltaG and DeltaS at different temperatures were calculated. The results indicated that van der Waals interactions and hydrogen bonds were the predominant intermolecular forces in stabilizing the complex. The distance r=4.33 nm between the donor (BSA) and acceptor (PAAB) was obtained according to Förster's non-radioactive energy transfer theory. The synchronous fluorescence, CD and three-dimensional fluorescence spectral results showed that the hydrophobicity of amino acid residues increased and the losing of alpha-helix content (from 63.57 to 51.83%) in the presence of PAAB. These revealed that the microenvironment and conformation of BSA were changed in the binding reaction.

Rapid Equilibrium Kinetic Analysis of Arsenite Methylation Catalyzed by Recombinant Human Arsenic (+3 Oxidation State) Methyltransferase (hAS3MT)

“…In our test range, peak 1 was mainly dominated by the microenvironments of the tryptophan and tyrosine residues, and peak 2 mainly exhibited the fluorescence character of polypeptide backbone structures (37). Peak 2 of hAS3MT disappeared in both the GSH system and the cysteine system (Table 3).…”

“…The synchronous fluorescence spectra showed that the maximum emission wavelength of hAS3MT was slightly red-shifted in each reductive system (Table 2). Interestingly, red shifts were also observed with the titrated concentrations of AdoMet, demonstrating that the microenvironment around the active site was disturbed and that the hydrophobicity decreased in the presence of AdoMet (37). The fluorescence quenching efficiency of AdoMet on the enzyme calculated using (F 0 Ϫ F)/F 0 (%) was 28.91% in the cysteine system, 26.52% in the GSH system, and 19.46% in the TCEP system ( Table 2), confirming that AdoMet bound to hAS3MT more readily in the cysteine reductive condition than in the GSH or TCEP reductive condition.…”

A Study on the Binding of Loperamide to Human Serum Albumin Using Combination of Computational and Experimental Methods

“…These weak interactions are including hydrogen bonds, van der Waals forces, electrostatic and hydrophobic interactions [29].…”

“…The interacting forces between small molecules such as drugs and HSA show weak interactions such as electrostatic forces, hydrophobic interaction, hydrogen-bond formation, and van der Waals forces and stereo-hindrance effect [29]. In a typical binding procedure, the thermodynamic variables changes, such as enthalpy change (ΔH), entropy change (ΔS) and free energy change (ΔG) are the main factors for describing the binding modes and to determine the interactive forces.…”

Physicochemical Peculiarities of Iodine-Dimethylsulfoxide-H2O Solutions and Effect on Ion Binding to Bovine Serum Albumin

“…e absorption of inorganic-iodine, such as − , is certainly bound to serum albumin. Serum albumins, human serum albumin (HSA), and bovine serum albumin (BSA) play an important role in the transport and disposition of a wide variety of substances like metals, fatty acids, amino acids, hormones, and drugs [2][3][4][5][6]. Competitive interactions in the aqueous solutions containing DMSO and ions were a subject of numerous studies [7,8].…”