Effects of urea, metal ions and surfactants on the binding of baicalein with bovine serum albumin$ / 药物分析学报

The interaction of baicalein with bovine serum albumin (BSA) was investigated with the help of spec-troscopic and molecular docking studies. The binding affinity of baicalein towards BSA was estimated to be in order of 105 M?1 from fluorescence quenching studies. NegativeΔH° (?5.6670.14 kJ/mol) and positive (ΔS°) ( t 79.96 7 0.65 J/mol K) indicate the presence of electrostatic interactions along with the hydrophobic forces that result in a positiveΔS°. The hydrophobic association of baicalein with BSA di-minishes in the presence of sodium dodecyl sulfate (SDS) due to probable hydrophobic association of baicalein with SDS, resulting in a negativeΔS° ( ? 40.65 7 0.87 J/mol K). Matrix-assisted laser desorption ionization/time of flight (MALDI–TOF) experiments indicate a 1:1 complexation between baicalein and BSA. The unfolding and refolding phenomena of BSA were investigated in the absence and presence of baicalein using steady-state and fluorescence lifetime measurements. It was observed that the presence of urea ruptured the non-covalent interaction between baicalein and BSA. The presence of metal ions (Ag t , Mg2 t , Ni2 t , Mn2 t , Co2 t and Zn2 t ) increased the binding affinity of ligand towards BSA. The changes in conformational aspects of BSA after ligand binding were also investigated using circular di-chroism (CD) and Fourier transform infrared (FT-IR) spectroscopic techniques. Site selectivity studies following molecular docking analyses indicated the binding of baicalein to site 1 (subdomain IIA) of BSA.&2016 Xi'an Jiaotong University. Production and hosting by Elsevier B.V. This is an open access article.

Analytical quality-by-design approach for sample treatment of BSA-containing solutions / 药物分析学报

The sample preparation of samples containing bovine serum albumin (BSA), e.g., as used in transdermal Franz diffusion cell (FDC) solutions, was evaluated using an analytical quality-by-design (QbD) approach. Traditional precipitation of BSA by adding an equal volume of organic solvent, often successfully used with conventional HPLC-PDA, was found insufficiently robust when novel fused-core HPLC and/or UPLC-MS methods were used. In this study, three factors (acetonitrile (%), formic acid (%) and boiling time (min)) were included in the experimental design to determine an optimal and more suitable sample treatment of BSA-containing FDC solutions. Using a QbD and Derringer desirability (D) approach, combining BSA loss, dilution factor and variability, we constructed an optimal working space with the edge of failure defined as Do0.9. The design space is modelled and is confirmed to have an ACN range of 8373%and FA content of 170.25%.

In vitro Study of Interactions of Sildenafil Citrate with Bovine Serum Albumin in Presence of Bisoprolol Fumarate and Metformin Hydrochloride by Fluorescence Spectrophotometry.

Aims: This paper describes the In vitro study of protein binding by sildenafil citrate (SC) in presence of bisoprololfumarate (BF) and metformin hydrochloride (MH). Study Design: Study was designed to assess In vitro of quenching of bovine serum albumin (BSA) by sildenafil citrate (SC) in presence of bisoprolol fumarate (BF) and metformin hydrochloride (MH) by fluorescence spectrophotometry. Place and Duration of Study: Drug Analysis and Research Laboratory, Centre for Advanced Research in Sciences, University of Dhaka, Dhaka-1000, Bangladesh between December 2013 and March 2014. Methodology: In the present work, the In vitro study of quenching of BSA by SC in presence of BFand MH have been studied by fluorescence emission spectroscopy under different conditions. At first, the BSA solution (20 μM) was prepared in phosphate buffer (pH =7.4) in eight test tubes and different amounts of sildenafil citrate was added to each BSA solution to obtain the final concentrations as 0, 20, 40, 80, 120, 160,240 and 320 × 10-6 molL-1, respectively. Then the fluorescence emission spectra of BSA-SC system were recorded for eight test tubes at two excitation wavelengths of BSA (λExmax= 280 nm and λExmax=293 nm) at 298 K and 308 K. Similarly, the fluorescence emission spectra of BSA-(SC+BF), BSA-(SC+MH) and BSA-(SC+BF+MH) systems were recorded at 280 nm and293 nm at 298 K and 308 K. Quenching constants were determined using the Stern-Volmer equation to provide a measure of the strength of quenching of BSA by SC in presence of BF and MH in all the systems. Results: The quenching of BSA by SC was increased in presence of BF and MH but remained close in presence of both BF and MH. Quenching constants were larger for the BSA-(SC+BF) system and ranked in the order as BSA-(SC+BF)>BSA-(SC+MH)>BSA-(SC+BF+MH)≈ BSA-SC at 280 nm at two different temperatures, respectively. But quenching at the excitation wavelength of 293 nm was ranked in order as BSA-(SC+BF) >BSA-(SC+MH) >BSA-(SC+BF+MH)>BSA-SC at 298 K and 308 K, respectively. Conclusion: It was found that BSA quenched by SC in presence of BF and MH, which indicated that the effectiveness of SC might be predominately influenced by these drugs.

The Tribological and Lubrication Responses of a Cobalt-Chromium Femoral Head in Total Hip Arthroplasty

PURPOSE: This study aimed at investigating the role of albumin as a boundary lubricant in the lubrication of the Co-Cr femoral head of artificial hip implants by measuring the tribological parameters of the Co-Cr femoral head with Atomic Force Microscope (AFM) techniques. MATERIALS AND METHODS: Samples were prepared from the main wear region of a Co-Cr femoral head from revision hip surgery. Two types of solutions were prepared as lubricants: PBS (Phosphate Buffered Saline) as a control solution and BSA (Bovine Serum Albumin) as a lubricant at concentrations of 10, 20, 30 and 40 mg/ml in PBS solution. RESULTS: There were statistically significant differences in the frictional coefficients (micron) of a Co-Cr head between the PBS control and all the concentrations of BSA (10, 20, 30, 40 mg/ml) (P<0.001). Similarly, there were statistically significant differences for the micron between the BSA concentrations of 10, 20, 30 and 40 mg/m for all the cases except between the BSA of 30 and 40 mg/ml (P<0.01). CONCLUSION: There exists a maximum protein concentration of BSA to play a role as an effective boundary lubricant through adsorption on the surface of Co-Cr femoral head.

Occupational asthma caused by inhalation of bovine serum albumin powder

Bovine serum albumin (BSA), which is present in bovine plasma, is one of the major allergens affecting patients with food allergies induced by milk and meat. It is also commonly used in research laboratories. Although some reports have documented food allergies associated with BSA, BSA-induced occupational asthma has not been reported. We report a case of occupational asthma and rhinitis in a laboratory worker caused by the inhalation of BSA powder, in which an IgE-mediated response was suggested as the pathogenic mechanism.

Occupational asthma caused by inhalation of bovine serum albumin powder

Bovine serum albumin (BSA), which is present in bovine plasma, is one of the major allergens affecting patients with food allergies induced by milk and meat. It is also commonly used in research laboratories. Although some reports have documented food allergies associated with BSA, BSA-induced occupational asthma has not been reported. We report a case of occupational asthma and rhinitis in a laboratory worker caused by the inhalation of BSA powder, in which an IgE-mediated response was suggested as the pathogenic mechanism.

Characteristic of salvianolic acid binding to bovine serum albumin and structure-performance relationship / 中草药

Objective To study the characteristic of salvianolic acid(SA) binding to bovine serum albumin(BSA) and the structure-performance relationship.Methods The interactions between BSA and four natural SA(SAⅠ,rosmaric acid;SAⅡ,lithosperic acid;SAⅢ,salvianolic acid A;and SAⅣ,salvianolic acid B) were investigated by fluorescence and ultraviolet spectroscopy.Results The intrinsic fluorescence of BSA was quenched by SA via forming SA-BSA complexes and non-radiation energy transfer.The parameters of SA-BSA binding process,such as the static apparent association constant KA,the number of binding site n,the efficiency of energy transfer E,the spatial distance r were obtained,and the thermodynamic constants ?G,?H,and ?S were calculated.Conclusion The results indicate that SAⅢ bounds to BSA mainly through a hydrophobic force and the other three SA-BSA interactions are mainly driven by hydrogen bond and Van der Waals' force.Y,a comprehensive binding parameter constructing from the equation Y=lg (KA?E?n/r),could be used to reflect the interaction extent of SA-BSA system.The Y value changes with the number of free phenolic hydroxyl and molecule volume and decreases in the order of SAⅢ→SAⅣ→SAⅡ→SAⅠ.The results from correlation analysis indicate that it could be possible to estimate SA-BSA binding extent from hydrophobic parameter clogP and topo-polar surface area per unit of molecular weight tPSA/Mr of SA molecule.

Studies on the Interaction between Sulfur Dioxide and Bovine Serum Albumin by Fluorescence Spectrophtometry / 环境与健康杂志

Objective To explore the mechanism of the interaction between sulfur dioxide(SO2) and bovine serum albumin (BSA). Methods The spectrum characteristic of the interaction between SO2 and BSA was studied by fluorescence quenching spectrum and three dimensional fluorescence spectrum. Results The binding constants and thermodynamic parameters of SO2 with BSA were calculated at different temperatures. The quenching mechanism of BSA by SO2 was determined,the result showed that it did not belong to dynamic quenching but belonged to static quenching,which produced the complex. The hydrophobic interaction and electrostatic force played a main role in the binding of SO2 with BSA and only about one binding site occurred in the reaction. There was a certain influence to the conformation of BSA after adding SO2. Conclusion The quenching reaction of BSA by SO2 was weak. SO2 dissolved in body fluid easily and then SO32-and HSO3-are generated in vivo.