Fluorescence quenching and ligand binding: A critical discussion of a popular methodology

Interaction of malachite green with bovine serum albumin: determination of the binding mechanism and binding site by spectroscopic methods.

The binding mechanism of molecular interaction between diosmetin and human serum albumin (HSA) in a pH 7.4 phosphate buffer was studied using atomic force microscopy (AFM) and various spectroscopic techniques including fluorescence, resonance light scattering (RLS), UV–vis absorption, circular dichroism (CD), and Fourier transform infrared (FT–IR) spectroscopy. Fluorescence data revealed that the fluorescence quenching of HSA by diosmetin was a static quenching procedure. The binding constants and number of binding sites were evaluated at different temperatures. The RLS spectra and AFM images showed that the dimension of the individual HSA molecules were larger after interaction with diosmetin. The thermodynamic parameters, ΔH° and ΔS° were calculated to be −24.56 kJ mol–1 and 14.67 J mol–1 K–1, respectively, suggesting that the binding of diosmtin to HSA was driven mainly by hydrophobic interactions and hydrogen bonds. The displacement studies and denaturation experiments in the presence of urea indicate...

Probing the binding of the flavonoid diosmetin to human serum albumin by multispectroscopic techniques.

We located the binding sites of doxorubicin (DOX) and N-(trifluoroacetyl) doxorubicin (FDOX) with bovine serum albumin (BSA) and human serum albumins (HSA) at physiological conditions, using constant protein concentration and various drug contents. FTIR, CD and fluorescence spectroscopic methods as well as molecular modeling were used to analyse drug binding sites, the binding constant and the effect of drug complexation on BSA and HSA stability and conformations. Structural analysis showed that doxorubicin and N-(trifluoroacetyl) doxorubicin bind strongly to BSA and HSA via hydrophilic and hydrophobic contacts with overall binding constants of K(DOX-BSA) = 7.8 (± 0.7) × 10(3) M(-1), K(FDOX-BSA) = 4.8 (± 0.5)× 10(3) M(-1) and K(DOX-HSA) = 1.1 (± 0.3)× 10(4) M(-1), K(FDOX-HSA) = 8.3 (± 0.6)× 10(3) M(-1). The number of bound drug molecules per protein is 1.5 (DOX-BSA), 1.3 (FDOX-BSA) 1.5 (DOX-HSA), 0.9 (FDOX-HSA) in these drug-protein complexes. Docking studies showed the participation of several amino acids in drug-protein complexation, which stabilized by H-bonding systems. The order of drug-protein binding is DOX-HSA > FDOX-HSA > DOX-BSA > FDOX>BSA. Drug complexation alters protein conformation by a major reduction of α-helix from 63% (free BSA) to 47-44% (drug-complex) and 57% (free HSA) to 51-40% (drug-complex) inducing a partial protein destabilization. Doxorubicin and its derivative can be transported by BSA and HSA in vitro.

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Probing the Binding Sites of Antibiotic Drugs Doxorubicin and N-(trifluoroacetyl) Doxorubicin with Human and Bovine Serum Albumins

Intercalation of antitumor drug doxorubicin and its analogue by DNA duplex: Structural features and biological implications

Study of the interaction between icariin and human serum albumin by fluorescence spectroscopy

Spectroscopic studies on the interaction of morin–Eu(III) complex with calf thymus DNA

The interaction of puerarin and bovine serum albumin (BSA) under physiological condition was studied by fluorospectrophotometry. The experiment demonstrated that the quenching mechanism of puerarin a BSA was static quenching process. The quenching constant is 7.29 x 10(12) L x mol(-1) x s(-1), and the binding constant is 5.04 x 10(4) L x mol(-1). According to the Forster nonradiative energy transfer theory, the binding distance between donor (BSA) and acceptor (puerarin) was calculated to be 3.35 nm. The influence of the presence of puerarin on structure of BSA was studied by synochronous fluorescence method, the binding distance between BSA and puerarin was also measured, and the binding mechanism was discussed. In addition, the effect of some ions on the binding constant of puerarin with BSA was also studied.

Junhui Pan

Papers

Study of the interaction between icariin and human serum albumin by fluorescence spectroscopy

Spectroscopic studies on the interaction of morin–Eu(III) complex with calf thymus DNA

Studies on the interaction between puerarin and bovine serum albumin