Spectroscopic studies on the interaction between silicotungstic acid and bovine serum albumin

The binding interactions of three kinds of tyrosine kinase inhibitors (TKIs), such as gefitinib, lapatinib and sunitinib, with bovine serum albumin (BSA) were studied using ultraviolet spectrophotometry, fluorescence spectroscopy, circular dichroism (CD), Fourier transform infrared spectroscopy (FT-IR) and molecular docking methods. The experimental results showed that the intrinsic fluorescence quenching of BSA induced by the three TKIs resulted from the formation of stable TKIs-BSA complexes through the binding interaction of TKIs with BSA. The stoichiometry of three stable TKIs-BSA complexes was 1:1 and the binding constants (Kb) of the three TKIs-BSA complexes were in the order of 10(4)M(-1) at 310 K, indicating that there was a strong binding interaction of the three TKIs with BSA. Based on the analysis of the signs and magnitudes of the free energy change (ΔG(0)), enthalpic change (ΔH(0)) and entropic change (ΔS(0)) in the binding process, it can be deduced that the binding process of the three TKIs with BSA was spontaneous and enthalpy-driven process, and the main interaction forces between the three TKIs and BSA were van der Waals force and hydrogen bonding interaction. Moreover, from the results of CD, FT-IR and molecular docking, it can be concluded that there was a significant difference between the three TKIs in the binding site on BSA, lapatinib was located on site II (m) of BSA while gefitinib and sunitinib were bound on site I of BSA, and there were some changes in the BSA conformation when binding three TKIs to BSA but BSA still retains its secondary structure α-helicity.

Spectroscopic and molecular docking studies of binding interaction of gefitinib, lapatinib and sunitinib with bovine serum albumin (BSA).

A fluorescence spectroscopic study of the interaction between epristeride and bovin serum albumine and its analytical application.

In this work, the interaction of a naturally occurring chromene, flindersine (FL), and bovine serum albumin (BSA) has been investigated by UV-vis absorption and fluorescence spectroscopy, time-resolved lifetime measurements, steady state photochemistry, and semiempirical calculations. The interplay of FL with tryptophan (Trp) has been studied in parallel. The interaction of FL with BSA causes fluorescence quenching of BSA through both static and dynamic quenching mechanisms. FL binds BSA with a stoichiometry that varies from 1.09:1 to 0.80:1 as the temperature increases from 293 to 308 K. The reaction is characterized by negative enthalpy (deltaH degrees = -193 kJ mol(-1)) and negative entropy (deltaS degrees = -550 J K(-1) mol(-1)), indicating that the predominant forces in the FL-BSA complex are hydrogen bonding and van der Waals forces. The binding distance between the protein and the photochrome was calculated as 2.5 nm, according to the Foerster theory on resonance energy transfer. The effect of FL concentration on the BSA fluorescence was analyzed according to the maximum entropy method. FL also quenches the emission of Trp with a mechanism that, based on the experimental evidence, excludes both static and dynamic effects. An alternative relaxation pathway, consisting in an electron transfer from a prefluorescent state of Trp to FL, is put forward. The photobehavior of FL is affected by the interplay with BSA but not with Trp. When FL is complexed with BSA, it becomes a more fluorescent and more reactive species. Semiempirical calculations of the lowest optically active electronic transitions of hypothetical FL photoproducts suggest the most likely structure for the photoproduct.

Static and dynamic interaction of a naturally occurring photochromic molecule with bovine serum albumin studied by UV-visible absorption and fluorescence spectroscopy.

Binding of Sudan II and Sudan IV to bovine serum albumin: comparison studies.

Investigation of the association behaviors between biliverdin and bovine serum albumin by fluorescence spectroscopy.

In this paper we report on the low temperature phosphorescence (LTP), the low temperature fluorescence (LTF), the paper substrate room temperature phosphorescence (PS‐RTP), and the room fluorescence (RTF) properties of ciprofloxacin (CPFX), lomefloxacin (LMX), fleroxacin (FLX), and ofloxacin (OFLX), which were investigated and compared Some rules were discovered: their maximal excitation wavelength and emission wavelength are in the range of 280–295 nm and 428–500 nm, respectively, except OFLX, and the difference in molecular structure may be responsible for it The pH experiments show that all their emissions are strongest in acid, followed by neutral, and weakest in alkali medium The PS‐RTP characters of lifetime and polarization were also investigated and compared It was found that the lifetimes of PS‐RTP were all in the level of 01 s These quinolones belong to long‐life phosphorescence and their PS‐RTP spectra are incompletely polarized

Investigation on the Luminescence Performance of Four Quinolones

This article presents a new determination method for the analysis of ofloxacin (OFLX) by solid‐substrate room temperature phosphorescence (SS‐RTP) with filter paper as solid substrate and CdCl2 as heavy‐atom salt. Various factors affecting RTP intensity of OFLX, such as heavy‐atom effect, pH, and drying time of the sample, were studied in detail. The linear dynamic range (LDR), limit of detection, and RSD were: 1.03 to 411 ng/spot, 0.123 ng/spot and 1.7% for OFLX, respectively. The method was applied to determine OFLX in urine successfully. The recoveries of OFLX in urine were from 94.60% to 105.4%. The pharmacokinetic of OFLX was studied in urine as well. Mean accumulative excretion rate was 77.69%.

An Analytical Application of Ofloxacin by Solid‐Substrate Room Temperature Phosphorescence

The binding reaction of tetraiodofluorescein with bovine serum albumin i n aqueous solution was studied by fluorimetry.The binding constant is 2.65 x 10(5) L x mol(-1), the equilibrium constant is 5.7 x 10(4) L x mol(-1), and the binding number is 0.86. The research results of binding model indicate that the hydrophobic force was the main binding force. The presence of BSA can increase the fluorescence intensity of TIF. And the deltaF(F-F0) is linear to the concentration of BSA in a certain range, so the first analytical application was proposed. The linear dynamic range (LDR) was 8 x 10(-7) - 9 x 10(-6) mol x L(-1), the limit of detection (LOD) was 9.88 x 10(-8) mol x L(-1), and the relative standard deviation (RSD) was 3.4%.

Jian-qing Li

Papers

Investigation of the association behaviors between biliverdin and bovine serum albumin by fluorescence spectroscopy.

Investigation on the Luminescence Performance of Four Quinolones

An Analytical Application of Ofloxacin by Solid‐Substrate Room Temperature Phosphorescence

Study on the interaction of tetraiodofluorescein and bovine serum albumin by fluorimetry