Secondary Structure Of Bovine Serum Albumin Research Articles

Probing amikacin interaction with albumin: A combined multispectral and molecular docking investigation

The fate of a drug administered to a living organism depends on the pharmacological and pharmacokinetic behavior of drugs. Biological macromolecules like serum albumins have a crucial role in the design and biological safety assessments of drugs. Amikacin as an example of the most used semi-synthetic aminoglycosides antibiotics, is included in the crucial drug list of the World Health Organization. This in vitro study aimed to explore Amikacin's binding specification with bovine serum albumin (BSA) through a computational and experimental approach. According to fluorescence spectra, it was declared that the innate fluorescence emission of serum albumin was quenched by the Amikacin via a static quenching mechanism. Meantime, the binding constants and thermodynamic parameters of Amikacin with BSA were calculated at various temperatures. Based on this calculation, negative ΔG°, ΔH°, and ΔS° values showed that spontaneous binding process occurred via hydrogen bond and van der Waals interaction. Additionally, based on UV–vis absorption, Amikacin leads to conformational modifications of BSA with the construction of a ground state complex, which may affect the physiological functions of this serum albumin. The results of FTIR spectroscopy showed that the binding of amikacin led in the change of BSA secondary structure and confirmed the possibility of changing the physiological functions of BSA. It is anticipated that this research will supply significant insight into the pharmacological properties of Amikacin and its related effects on human health in vivo.

Interaction between reacetylated chitosan and albumin in alcalescent media

Interaction of chitosan and its derivatives with proteins of animal blood at blood pH relevant conditions is of a particular interest for construction of antimicrobial chitosan/protein-based drug delivery systems. In this work, the interaction of a series of N-reacetylated oligochitosans (RA-CHI) having Mw of 10–12 kDa and differing in the degree of acetylation (DA 19, 24, and 40 %) with bovine serum albumin (BSA) in alkalescent media is described in first. It is shown that RA-CHI forms soluble complexes with BSA in solutions with pH 7.4 and a low ionic strength. Light scattering study shows that soluble RA-CHI complexes have spherical form with the radius of about 100 nm. Circular dichroism, fluorescent spectroscopy, and micro-IR spectroscopy studies show that the secondary structure of BSA in soluble complexes remain intact. Isothermal titration calorimetry of RA-CHI with DA 24 % and BSA mixing in the buffers with different ionization heats reveals a significant contribution of electrostatic forces to the binding process and an additional ionization of chitosan due to the proton transfer from the buffer substance. An increase of ionic strength to the blood relevant value 0.15 M suppresses the binding. It is shown that application of RA-CHI with higher DA value leads to a decrease in the affinity of RA-CHI to BSA and an alteration of the interaction mechanism. The finding opens an opportunity to the application of N-reacetylated chitosan derivatives in the complex systems compatible with blood plasma proteins.

BSA Binding and Aggregate Formation of a Synthetic Amino Acid with Potential for Promoting Fibroblast Proliferation: An In Silico, CD Spectroscopic, DLS, and Cellular Study.

This study presents the chemical synthesis, purification, and characterization of a novel non-natural synthetic amino acid. The compound was synthesized in solution, purified, and characterized using NMR spectroscopy, polarimetry, and melting point determination. Dynamic Light Scattering (DLS) analysis demonstrated its ability to form aggregates with an average size of 391 nm, extending to the low micrometric size range. Furthermore, cellular biological assays revealed its ability to enhance fibroblast cell growth, highlighting its potential for tissue regenerative applications. Circular dichroism (CD) spectroscopy showed the ability of the synthetic amino acid to bind serum albumins (using bovine serum albumin (BSA) as a model), and CD deconvolution provided insights into the changes in the secondary structures of BSA upon interaction with the amino acid ligand. Additionally, molecular docking using HDOCK software elucidated the most likely binding mode of the ligand inside the BSA structure. We also performed in silico oligomerization of the synthetic compound in order to obtain a model of aggregate to investigate computationally. In more detail, the dimer formation achieved by molecular self-docking showed two distinct poses, corresponding to the lowest and comparable energies, with one pose exhibiting a quasi-coplanar arrangement characterized by a close alignment of two aromatic rings from the synthetic amino acids within the dimer, suggesting the presence of π-π stacking interactions. In contrast, the second pose displayed a non-coplanar configuration, with the aromatic rings oriented in a staggered arrangement, indicating distinct modes of interaction. Both poses were further utilized in the self-docking procedure. Notably, iterative molecular docking of amino acid structures resulted in the formation of higher-order aggregates, with a model of a 512-mer aggregate obtained through self-docking procedures. This model of aggregate presented a cavity capable of hosting therapeutic cargoes and biomolecules, rendering it a potential scaffold for cell adhesion and growth in tissue regenerative applications. Overall, our findings highlight the potential of this synthetic amino acid for tissue regenerative therapeutics and provide valuable insights into its molecular interactions and aggregation behavior.

An investigation of the binding of two cinnamate UV filters to bovine serum albumin separately and simultaneously

A study of the separate/simultaneous interaction mechanism between two common cinnamate ultraviolet filters (UVFs), Octtocrylene (OC) and 2-ethylhexyl 4-methoxycinnamate (EHMC), with bovine serum albumin (BSA) was conducted. Both OC and EM can bind to BSA. A more obvious fluorescence quenching effect was observed with EHMC on BSA, as well as a stronger affinity for BSA and a greater effect on the amino acid microenvironment. UVFs and BSA's binding constants were decreased when EHMC and OC interacted simultaneously with BSA, while the distance between UVFs and BSA was increased. Coexistence affected both OC and EHMC, making them less able to binding to BSA. While binding simultaneously to EHMC and OC, BSA's secondary structure underwent significant changes.

Spectroscopic study of drug–drug interactions: influence of two over-the-counter drugs on the albumin binding affinities of carbamazepine and its major metabolite

BackgroundMultidrug regimens can increase the risk of drug–drug interactions at the level of albumin binding especially for drugs with narrow therapeutic windows such as carbamazepine (CBZ). This risk is particularly heightened for CBZ which is mainly metabolized to the active carbamazepine-10,11-epoxide (CBZE) that has been identified as contributory to both the therapeutic efficacy and severity of toxicity in CBZ-treated individuals. The objective of this study was to investigate the binding affinities of albumin with CBZ and CBZE, and to explore the influence of two competing over-the-counter medicines on the binding characteristics. CBZE was synthesized by epoxidation of CBZ and characterized using IR, NMR and mass spectrometry. The influence of paracetamol and ascorbic acid on the albumin complexes of CBZ and CBZE was investigated using absorption and IR spectrophotometry.ResultsProtein–ligand complexation produced progressive hyperchromic changes in 278 nm band of bovine serum albumin (BSA) with formation constants of 10.28–10.44 and 12.66–13.02 M−1 for CBZ and CBZE, respectively. Thermodynamic considerations confirmed both binding processes as endothermic, spontaneous and driven by hydrophobic interactions. The presence of ascorbic acid increased the binding constants of both CBZ-BSA and CBZE-BSA complexes by non-competitive interference mechanism. Similarly, paracetamol increased the affinity of CBZ for albumin but then competitively interfered with the CBZE-BSA complex. The ratio of albumin binding affinities of CBZ–CBZE varied from 0.81 in the absence of competing drug to 1.29 and 1.0 with paracetamol and ascorbic acid, respectively. IR study confirmed that both CBZ and CBZE induced a reduction from the 67.34% α-helical content of free BSA to 42.56 and 56.43%, respectively. Competitive binding in the presence of either paracetamol or ascorbic acid induced further reduction in the α-helical content of BSA in the complexes. The most extensive perturbation in the secondary structure of BSA (22.78% α-helical content) which was observed with CBZE-BSA complex in the presence of paracetamol is probably due to the increased interaction of the protein for the analgesic.ConclusionThe study has revealed potential interference of paracetamol or ascorbic acid with the albumin binding of carbamazepine and its major metabolite.

The Morphology Dependent Interaction between Silver Nanoparticles and Bovine Serum Albumin.

Biological applications of silver nanoparticles (AgNPs) depend on the covalently attached or adsorbed proteins. A series of biological effects of AgNPs within cells are determined by the size, shape, aspect ratio, surface charge, and modifiers. Herein, the morphology dependent interaction between AgNPs and protein was investigated. AgNPs with three different morphologies, such as silver nanospheres, silver nanorods, and silver nanotriangles, were employed to investigate the morphological effect on the interaction with a model protein: bovine serum albumin (BSA). The adsorptive interactions between BSA and the AgNPs were probed by UV-Vis spectroscopy, fluorescence spectroscopy, dynamic light scattering (DLS), Fourier transform infrared spectrometry (FTIR), transmission electron microscopy (TEM), and circular dichroism (CD) techniques. The results revealed that the particle size, shape, and dispersion of the three types of AgNPs markedly influence the interaction with BSA. Silver nanospheres and nanorods were capsulated by protein coronas, which led to slightly enlarged outer size. The silver nanotriangles evolved gradually into nanodisks in the presence of BSA. Fluorescence spectroscopy confirmed the static quenching the fluorescence emission of BSA by the three AgNPs. The FTIR and CD results suggested that the AgNPs with different morphologies had different effects on the secondary structure of BSA. The silver nanospheres and silver nanorods induced more pronounced structural changes than silver nanotriangles. These results suggest that the formation of a protein corona and the aggregation behaviors of AgNPs are markedly determined by their inherent morphologies.

Characterization of a chlorine resistant and hydrophilic TiO2/calcium alginate hydrogel filtration membrane used for protein purification maintaining protein structure

The development of membranes for protein purification has stringent requirement of disinfection resistance, low protein adsorption and anti-fouling, without changing protein structure. In this study, hydrophilic titanium dioxide (TiO2)/calcium alginate (TiO2/CaAlg) hydrogel membranes were prepared by a simple ionic cross-linking method. The effects of the porogenic agent polyethylene glycol (PEG) concentration, the molecular weight of PEG, and the concentration of TiO2 on the filtration properties were systematically investigated. The TiO2/CaAlg membrane exhibited excellent bovine serum albumin (BSA) rejection and anti-fouling properties. The mechanical properties and surface energy of the TiO2/CaAlg membrane were significantly improved. The chemical bonding mechanism of TiO2 and NaAlg was investigated by molecular dynamic simulation. The TiO2/CaAlg membrane had good chlorine resistance and could be disinfected or cleaned with sodium hypochlorite. The TiO2/CaAlg hydrogel membrane loaded with polyhydroxybutyrate (PHB) nanofibers maintained high flux (136.7 L/m2h) and high BSA rejection (98.0 %) at 0.1 MPa. The results of circular dichroism and synchronous fluorescence indicated that the secondary structure of BSA was maintained after membrane separation. This study provides one method for the preparation of green and environmentally friendly membrane for protein purification.

Exploring the binding behaviors between nisoldipine and bovine serum albumin as a model protein by the aid of multi-spectroscopic approaches and in silico

Bovine serum albumin (BSA), a model protein was used to evaluate the binding behavior of nisoldipine and human serum albumin by a series of experiments and in silico in this article. The outcomes suggested that nisoldipine and BSA formed the nisoldipine-BSA complex with a molar ratio of 1:1, caused the fluorescence quenching of BSA, which quenching mechanism was attributable to static quenching. The binding constant of the nisoldipine-BSA complex was (1.3–3.0) × 104 M−1 at 298–310 K, indicating that nisoldipine on BSA protein had a moderate affinity. During the complexation of nisoldipine with BSA, nisoldipine can spontaneously insert into the site II (subdomain III A) of BSA and the distance of energy transfer from donor group in protein to acceptor group in nisoldipine was 3.21 nm, which led to the change in the hydrophobicity of the microenvironment surrounding Trp residues and in the secondary structure of BSA. Additionally, the findings also confirmed that the hydrogen bond and van der Waals force were responsible for forming the nisoldipine-BSA complex and the complexation process was a spontaneous exothermic process. Communicated by Ramaswamy H. Sarma

Para-Cresyl Sulfate and BSA Conjugation for Developing Aptasensor: Spectroscopic Methods and Molecular Simulation

Para-cresol sulfate (PCS), a protein-bound uremic toxin, is gut microbiota derived metabolite and known for its role in human physiology and pathology. After PCS formation, it goes to blood stream and interact with serum albumin with high affinity. Normally, PCS is cleared by the kidney but if it gets accumulated then leads to chronic kidney disease (CKD). Present study is an attempt to understand the nuances of interaction wherein bovine serum albumin (BSA) has been taken as model protein to understand this interaction. Absorption spectroscopy result indicated that in presence of PCS (ranging from 2 μM to 200 μM), the absorbance of BSA gradually decreased due to complex formation between them and obtained detection limit of 0.42 μM with a linearity of 0.95. Fourier transform infra-red and circular spectroscopy results demonstrated change in secondary structure of BSA upon interaction of PCS. These interaction studies reveal that PCS binds on two sites of BSA. Docking studies represent binding score of −5.6 Kcal mol−1, demarking that PCS is involved in interaction with BSA via amino acid residues, forming the stable complex. This study helps in PCS aptamers synthesis by using this conjugate, to fabricate apta-sensors for early detection of CKD.

Combined experimental/computational aspects for the molecular interaction of empagliflozin with bovine serum albumin: Quantification and application to human plasma.

Empagliflozin (EMP) is an oral antihyperglycemic agent for type 2 diabetic patients. The molecular binding of EMP to bovine serum albumin (BSA) was elucidated by a combined experimental/computational approach to fulfil the pharmacokinetics and pharmacodynamics gaps of the cited drug for further development. Fluorescence, synchronous, and three-dimensional fluorescence spectroscopy verified that EMP quenched BSA native fluorescence through a dual static/dynamic mechanism that was further supported by Fӧrster resonance energy transfer and ultraviolet absorption spectroscopy. Fourier transform infrared spectroscopy revealed the conformational variations in BSA secondary structure induced by EMP. Thermodynamic properties of the BSA-EMP complex were also investigated, and the hydrophobic interactions' role in the binding process was demonstrated by the computed enthalpy (ΔH =6.558 kJ mol-1 ) and entropy (ΔS = 69.333 J mol-1 K-1 ). Gibbs free energy (ΔG) values were negative at three distinct temperatures, illuminating the spontaneity of this interaction. In addition, molecular docking studies depicted the optimal fitting of EMP to BSA on Site I (sub-domain IIA) through three hydrogen bonds. Additionally, and based on the quenching effect of EMP on BSA fluorescence, this study suggests a simple validated spectrofluorometric method for the quantitation of the studied drug in bulk form and human plasma samples with reasonable recoveries (96.99-103.10%).

Probing the interaction of tert-butylhydroquinone and its β-cyclodextrin inclusion complex with bovine serum albumin

Tert-butylhydroquinone (TBHQ) is a synthetic antioxidant found widely in foods such as cooking oil, fried baked goods and meat products, however, if consumed in excessive quantities, it may cause nutritional problems and chronic diseases. The binding of TBHQ to transport protein before and after β-cyclodextrin (β-CD) encapsulation was investigated by multiple spectroscopies and molecular docking technology. At 298 K, the binding constant, enthalpy, and entropy of bovine serum albumin (BSA) with TBHQ were (1.18 ± 1.50) × 104 M−1, (−110.11 ± 15.29) kJ mol−1 and (−293.36 ± 50.87) J mol−1 K−1 at 298 K, respectively. By forming a stable complex with BSA through van der Waals forces and hydrogen bonds, TBHQ altered BSA's secondary structure and microenvironmental polarity. However, the binding affinity of TBHQ with BSA decreased after encapsulation by β-CD, but the binding distance increased. Because of the encapsulation of β-CD, the interference of TBHQ with the BSA conformation was also inhibited. Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscope study confirmed the formation of an inclusion complex between CD and TBHQ. According to UV spectroscopy, TBHQ and β-CD have a binding constant of (1.21 ± 0.03) × 103 M−1. The formation of TBHQ–β-CD inclusion complex inhibited the binding of TBHQ and BSA, possibly because the inclusion of β-CD prevented TBHQ from entering the hydrophobic cavity of BSA, which prevented TBHQ from binding to BSA, alleviating the negative effects of TBHQ on BSA conformation. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging results showed that the antioxidant activity of TBHQ was not affected by β-CD encapsulation.

Binding Investigation of Some Important Metal Ions Copper (I), Nickel (II), and Aluminium (III) with Bovine Serum Albumin Using Valid Spectroscopic Techniques

Studies based on the interaction of metals with proteins resulted in the development of promising metal-based compounds with encouraging medicinal potential. This study was aimed to utilize FT-IR and UV-Vis spectroscopic techniques to analyze the interactions of biologically significant metal ions, such as Al3+, Ni+2, and Cu+, with bovine serum albumin (BSA). Different concentrations of metal ions were interacted with BSA, and the complexes were analyzed using the two techniques. The change in the BSA secondary structure components such as β-sheet, β-antiparallel, α-helix, β-turn, and random coil were analyzed using second derivative resolution enhancement. The FT-IR spectroscopy suggested a marked decrease in the C=O stretching (corresponding to amide I) and C=N stretching (corresponding to amide II) intensities. Interestingly, upon complexation, a marked reduction (22.58–29.03%) in the α-helical component was observed with a considerable increase in the random coil component. The intensity of the absorption peak of BSA obtained using UV was observed to increase consecutively as the concentration of Cu+, Al3+, and Ni2+ ions increased. The binding constants for the BSA-Cu+, BSA-Ni+2, and BSA-Al+3 complexes were calculated to be 3.46 × 104 M−1, 1.28 × 104 M−1, and 2.08 × 104 M−1, respectively. It was concluded that the binding interaction decreased in the order Cu+ > Al3+ > Ni2+. These findings were similar to our previous findings using affinity capillary electrophoresis (ACE). Therefore, it can be inferred that the FT-IR and UV techniques might be utilised effectively to assess the metal-protein interaction and can have wide application in routine analysis. These techniques have several advantages in being simple, easy-to-perform, rapid, and affordable over other high-end techniques.

Biophysical study of cisplatin loaded albumin-gold nanoparticle and its interaction with glycans of gp60 receptor

The biophysical study provides a quantitative understanding of biomolecular interaction. The interaction of protein-nanoparticle has been critically examined using various biophysical and biochemical tools. The present investigation focussed on the biophysical characterization of anticancer drug cisplatin (CPT) with Bovine Serum Albumin (BSA) - Gold nanoparticles (GNP) conjugate; and BSA-CPT-GNP interaction with glycan sugars of glycoprotein receptor. Spectroscopic study (UV visible and fluorescence) showed strong binding of CPT loaded BSA with GNP. The binding between BSA-CPT-GNP and glycan sugars of gp60 receptor was estimated. Circular Dichroism (CD) spectroscopy study revealed weak alteration in the secondary structure of BSA upon CPT and GNP binding. Dynamic Light Scattering (DLS) data indicated the changes in the size of conjugates; zeta potential data showed the stability of conjugates. Biocompatible studies showed no toxicity to RBCs and chorioallantoic membrane (CAM). The mechanisms of interaction have been explored at the molecular and cellular levels. This investigation can be effectively extrapolated for in-vivo and in-vitro targeted drug delivery studies for cancer therapy.

Effect of Cu2+ and Al3+ on the interaction of chlorogenic acid and caffeic acid with serum albumin

Despite the phenolic acids' health benefits, their interactions with proteins are still unclear. In this study, the interactions of Bovine Serum Albumin (BSA) with chlorogenic acid (CHA), caffeic acid (CA), and their Al3+, Cu2+ complexes were studied by using circular dichroism (CD) spectroscopy, fluorescence spectroscopy, and UV/Vis spectroscopy. It was found that esterification of carboxyl group of CA with quinic acid increased the binding affinities for BSA. After chelating with Cu2+ and Al3+, both CHA and CA exhibited high binding affinities for BSA. CHA could form CHA-Cu2 and CHA-Al2 complex with Cu2+ and Al3+. The result of CD spectroscopy demonstrated that the binding of CHA and Al3+ with BSA contributed to the folding of BSA secondary structure. In addition, with the presence of CHA, binding with Al3+ could also induce changes in BSA conformation. The binding sites of both CHA and CA were closed to Trp213.

Spectroscopic studies on binding of ibuprofen and drotaverine with bovine serum albumin

The interaction between ibuprofen (analgesic) and drotaverine (smooth muscle relaxant) drugs with bovine serum albumin (BSA) was investigated using both experimental (UV–Vis, fluorescence, and circular dichroism spectroscopy) and theoretical (molecular mechanics) methods. Both drugs quench the intrinsic fluorescence of BSA through static processes. The binding constant of the BSA–drotaverine complex is found to be relatively higher than that of the BSA–ibuprofen complex. The binding distance between BSA and ibuprofen/drotaverine was calculated to be 1.7 and 3.1 nm, respectively. Both fluorescence and circular dichroism spectral studies confirmed conformational changes in the BSA upon binding with these drugs. From both displacement competition studies and molecular docking, it was found that drotaverine can displace ibuprofen at higher concentrations, but ibuprofen can bind to other sites on the BSA. Circular dichroism showed that drotaverine has a stabilizing effect on the secondary structure of BSA in the presence of ibuprofen, which on its own leads to an increase in the disordered fraction at high concentrations.These observations imply that concurrent administration of these two drugs can be effective as a combination therapy in the management of pain due to primary dysmenorrhea, even when the disease tends to gain resistance to the NSAIDs; their competition for the BSA binding sites should be taken into account.

Multi-spectroscopies and molecular simulation insights into the interaction mechanism of bovine serum albumin and syringaldehyde

Syringaldehyde (Syr) is a natural product with significant biological activities. This study investigated the interaction mechanism of bovine serum albumin (BSA) and Syr through multi-spectroscopies and molecular simulation. The spectroscopy results indicated the binding mechanism of BSA and Syr was static quenching, and the microenvironment of Trp and Tyr residues had changed. Thermodynamic analysis showed that the hydrogen bond and van der Waals force were the main force during the formation of the BSA-Syr complex. The BSA secondary structure changed, and protein became disordered and aggregated with each other with the adding of Syr. Molecular simulation illustrated the Syr mainly bound Trp 213 and Ser 343 of BSA, and formed stable complexes in vivo. It provides guidance for further obtaining highly active Syr analogs. In conclusion, our research provides a theoretical direction for the practical application of Syr and a proposed framework for improving phenolic compounds utilization.

Detrimental Effects of Elevated Temperatures on the Structure and Activity of Phenylalanine Ammonia Lyase-Bovine Serum Albumin Mixtures and the Stabilizing Potential of Surfactant and Sugars.

We propose encapsulating phenylalanine ammonia lyase (PAL)-bovine serum albumin (BSA) mixtures as potential oral therapy for the management of phenylketonuria. PAL will metabolize phenylalanine in the gastrointestinal tract while BSA will minimize product inhibition and allow PAL to work at its Vmax. We intend manufacturing microcapsules using spray drying and the proteins will be exposed to heat. In the current pre-formulation studies, we determined the effect of elevated temperatures on the structure and activity of PAL-BSA mixtures and evaluated the stabilizing potential of excipients. Exposure of PAL to 75°C decreased its Vmax. BSA exacerbated the elevated temperature-mediated decrease in PAL Vmax and completely lost the ability to protect PAL from trans cinnamic acid (TCA)-mediated product inhibition. Circular dichroism studies revealed that elevated temperatures did not affect the secondary structure of PAL but decreased BSA α-helicity. Binding experiments showed that elevated temperature-mediated loss in BSA α-helicity was associated with markedly decreased binding and sequestration of TCA, which accounts for the inability of BSA to relieve PAL product inhibition. Sucrose, trehalose, and low concentrations of sodium dodecyl sulfate conferred concentration dependent stabilization of BSA secondary structure against thermal denaturation. The sugars enhanced PAL Vmax, markedly improved TCA binding to BSA, and restored the ability of BSA to relieve PAL product inhibition. PAL-BSA mixtures exposed to elevated temperatures in the presence of sucrose and trehalose exhibited high and constant PAL activity. The results justify inclusion of these sugars in the eventual microcapsule manufacturing process.

Insight into binding mechanism between three whey proteins and mogroside V by multi-spectroscopic and silico methods: Impacts on structure and foaming properties

In this work, the interaction mechanism, structure and foaming properties between three whey proteins (α-lactalbumin (ALa), β-lactoglobulin (BLg) and bovine serum albumin (BSA)) and Mogroside V (Mog) at pH 7.0 were systematically formulated via multi-spectroscopic analysis and silico methods. Mog quenched the fluorescence of three whey proteins in a static mode. Mog had greater binding affinity for ALa than that for BLg or BSA. Hydrogen bonds, van der Waals force and hydrophobic interaction acted as the primary driven forces in ALa/BLg/BSA-Mog system. Moreover, content of α-helix in ALa and β-sheet in BLg decreased after Mog addition, whereas there was no significant change in the secondary structure of BSA. In addition, hydrophobic crevice in ALa, “bottom of β-barrel” in BLg and interfacial region between two domains in BSA were the binding areas for Mog using molecular docking. Molecular dynamics (MD) simulation further demonstrated that the complex of ALa and Mog possessed the lowest binding free energy and most stable state. Furthermore, compared with single proteins, the foaming ability of protein/Mog complexes were improved. Especially, Ala-Mog attained the highest increase rate. Bubble morphology presented that three whey proteins containing Mog possessed compacter, smaller and even bubbles. This research could establish theoretical basis for the binding mechanism between different food proteins and low weight surfactants. Besides, whey protein-saponin complexes could be served as the novel food-grade foaming agents applied in food industry.

Spectroscopic investigation on the interaction of direct yellow-27 with protein (BSA)

Direct yellow 27 (DY-27) interaction with bovine serum albumin (BSA) was investigated using multi-spectroscopic techniques to understand the toxicity mechanism. Fluorescence quenching of BSA by DY-27 was observed as a result of the formation of a BSA-DY27 complex with a binding constant of 1.19 × 105 M−1 and followed a static quenching mechanism with a quenching constant Ksv of 7.25 × 104 M−1. The far UV circular dichroism spectra revealed the conformational changes in the secondary structure of BSA in the presence of DY-27. The calculated average lifetime of BSA is 6.04 ns and is nearly constant (5.99 ns) in the presence of dye and supports the proposed quenching mechanism. The change in free energy (ΔG) was calculated to be −28.96 kJ mol−1 and confirmed the spontaneity of the binding process. Further, docking studies have been conducted to gain more insights into the interactions between DY-27 and serum albumin.

A Survey of Gasoline Ameliorator, Methyl-Tert-Butyl Ether (MTBE) on Bovine Serum Albumin: A Spectroscopy and Molecular Dynamic Simulation Study.

Methyl-Tert-Butyl Ether (MTBE) as a gasoline modifier is frequently added to fuels and used in plenty of worldwide applications. MTBE biodegradation in groundwater occurs slowly and produces water miscibility; therefore, it causes diverse environmental and human health concerns. The interaction of MTBE with bovine serum albumin (BSA) as a model protein at physiological conditions is investigated to illustrate the possible interactions of MTBE with the body's proteins. Uv-visible, fluorescence, circular dichroism (CD) spectroscopy methods, and molecular modeling were used to analyze the MTBE's effect on BSA structure and dynamics. The constant protein concentration and various MTBE contents were used for possible interactions. The protein structural analysis shows that MTBE binds to BSA via positive enthalpy and entropy via hydrophobic interactions. Molecular docking shows the participation of several amino acids in the MTBE-BSA interaction. The CD spectroscopy results show that the BSA structure was not changed in the MTBE concentrations utilized in the study. Molecular dynamics (MD) simulation results suggest that MTBE can slightly change protein structure in the last 50ns. Comparing experimental and MD simulation results demonstrated that the BSA secondary structure was maintained in the low concentration of the MTBE. The entropy and enthalpy parameters asserted the hydrophobic interaction was the major force in the interaction between the BSA and MTBE.