Spectral study of coumarin-3-carboxylic acid interaction with human and bovine serum albumins

Abstract

Abstract:© Versita Sp. z o.o. Fluorescence spectroscopy and circular dichroism (CD) spectroscopy were used to investigate the interaction of coumarin-3-carboxylic acid with human serum albumin (HSA) and bovine serum albumin (BSA) under physiological conditions in a buffer solution of pH 7.4.Quenching constants were determined using the Lineweaver-Burk equation to provide a measure of the binding affinity of coumarin-3-carboxylic acid to HSA/BSA. Binding studies concerning the number of binding sites, n, and apparent binding constant, K, were performed by a fluorescence quenching method at different temperatures (298, 303 and 310 K). The thermodynamic parameters, enthalpy change (ΔH 0 ) and entropy change (ΔS 0 ) as calculated according to the van't Hoff equation, indicated that hydrogen bonding and van der Waals forces play a major role in coumarin-3-carboxylic acid-HSA association whereas electrostatic interactions dominate in coumarin-3-carboxylic acid-BSA association. The distance, r, between the donor (HSA/BSA) and acceptor (coumarin-3-carboxylic acid) has been estimated using Förster's equation, on the basis of resonance energy transfer. Furthermore, CD spectra were used to investigate the α-helix changes of the HSA and BSA molecules upon addition of coumarin-3-carboxylic acid.

Transition-Metal-Free CO-Releasing BODIPY Derivatives Activatable by Visible to NIR Light as Promising Bioactive Molecules

“…Compound 3a is soluble in aqueous solutions (>5 mM), and the pK a of its carboxylic group in an aqueous solution, determined by potentiometric titration, was found to be (3.0 ± 0.2) (Figure S30). This value corresponds well with the pK a 's of coumarine-3-carboxylic acid 41 or xanthene-9-carboxylic acid (1). 33 Compound 3a therefore exists as its conjugate base at physiological pH.…”

Optical Spectroscopic Exploration of Binding of Cochineal Red A with Two Homologous Serum Albumins

“…The CD spectra of proteins in presence and absence of Cochineal Red A are similar in shape, indicating that their structure after dye binding is also predominantly α-helical . Results obtained are analyzed in terms of mean residue ellipticity (MRE, deg·cm 2 ·dmol –1 ) according to the following equation: normalMRE = normalθ italicobs 10 n l c normalp where θ obs is the observed ellipticity in millidegrees at 208 nm, n is the number of amino acid residues, l is the path length of the cell, and c p is the molar concentration of the protein. The values of n are taken as 583 and 585 for BSA and HSA, respectively .…”

“…The observed α-helix contents of free HSA and BSA are 55.6% and 51.7%, respectively, in agreement with reported results. 29,30 Figure 7 indicates the decrease of α-helix percentage of proteins with increasing dye concentration. The helical content of are found to be 54.3% and 51.5% for HSA and BSA, respectively, at a protein:Cochineal Red A molar ratio of 1:2.…”

Exploring the interaction of 5,6- benzocoumarin-3-carboxylic acid with bovine serum albumin at the molecular level: A biophysical investigation using molecular dynamics

“…[10][11][12] Coumarin derivatives exhibit strong fluorescence in the visible region of the electromagnetic spectrum and have been studied extensively for the applications of fluorescent * Corresponding author: sorana@gw-chimie.math.unibuc.ro receptors, 13 fluorescent whiteners, 14 organic electroluminescent materials, 15 construction of photocleavable biomaterials and bioconjugates. 16 Previous studies using fluorescence spectroscopy and circular dichroism (CD) spectroscopy under physiological conditions on coumarin compounds revealed 3-carboxycoumarin interacts with human (HSA) and bovine (BSA) serum albumins, 17 while the induced circular dichroism (ICD) spectra of 3-carboxycoumarin in correlation with theoretical (TDDFT) calculations have been used to obtain the binding constants and information on the conformational changes of the ligand in the binding site of proteins. 18 The photophysical properties and the behaviour in electron transfer processes of 3-carboxy-5,6-benzocoumarinic acid have been previously studied in organic solvents, in aqueous media and in the presence of aromatic amines.…”