Search

It is of great significance to search for advanced glycation end products (AGEs) inhibitors with high activity and low side effects from food-borne natural products for the prevention and improvement of related diseases. To elucidate the inhibitory effect of tectoridin on the generation of advanced glycation end products (AGEs), the glycation system of bovine serum protein (BSA)-methylglyoxal (MGO) was established, the effects of tectoridin on the AGEs inhibition, glycation degree, protein oxidation products, protein cross-linking and MGO trapping were investigated by spectroscopy, SDS-PAGE, HPLC, LTQ-Orbitrap MS, and molecular docking. The results showed that tectoridin increased the content of lysine and thiol, reduced the contents of protein carbonylation and protein oxidation products, alleviated the cross-linking structure of BSA. The mono-MGO adduct of tectoridin was identified in the incubation of MGO with tectoridin. Molecular docking results showed that hydrogen bonding and hydrophobic interactions were the major driving forces for stabilizing tectoridin-BSA complexes. Tectoridin was a promising natural AGEs inhibitor. Mechanism analysis revealed that tectoridin alleviated AGEs formation by trapping MGO to form mono-tectoridin-MGO complexes and forming stable tectoridin-BSA complexes. These findings would provide the theoretical basis for the development of tectoridin as a novel, natural and effective inhibitor of AGEs.

In this study, the interactions of six different flavonoids (IVa~c and Va~c) with bovine serum proteins (BSA) were investigated by fluorescence spectroscopy, thermodynamic and molecular dynamics simulations. The fluorescence behaviors of IVa~c and Va~c were quantitatively related to BSA, and the results calculated using the Stern-Volmer equation showed that IVa~c and Va~c had significant fluores-cence quenching with BSA, both of which were static quenching. The binding ability of monofluoroflavone with BSA was best when its fluorine atom was at para position, while the binding ability of monofluoroflavonol with BSA was best when its fluorine atom was at meta position. The binding ability of monofluoroflavonol with BSA was stronger than that of monofluoroflavone when hydroxyl group was attached to the C(3) of monofluoroflavone IVa~c. The calculated thermodynamic parameters of IVa~c and Va~Va were ΔG<0, ΔH<0 and ΔS<0, indicating that the interaction of IVa~c and Va~Vc with BSA was a spontaneous exothermic process, which mainly relies on hydrogen bonding and van der Waals force. [ABSTRACT FROM AUTHOR]

The interaction of polyphenols with proteins depends on the structure and type of protein and polyphenols. This study aims to determine the interaction between different plant polyphenols and bovine serum albumin (BSA), as well as their influence on protein structure, proanthocyanidins (proanthocyanidins, PC), catechin (catechin, C), epigallocatechin gallate (Epigallocatechin gallate, EGCG), and tea polyphenols (TEA polyphenol, TP). The BSA was combined to form a polyphenolsBSA. The interaction of polyphenols with BSA and their effects on protein structure were analyzed by UV spectroscopy, fluorescence spectroscopy, infrared spectroscopy, and molecular docking. The results showed that the maximum absorption peak of BSA at 286 nm all shared an upward trend in a redshift with the increase of PC, C, EGCG and TP added. There was the UV maximum wavelength redshift EGCG (292 nm) >PC (288 nm), C (288 nm), TP (288 nm). The redshifted absorption peak was attributed to the EGCG as a monomer, more accessible to the hydrophobic amino acid residues of protein molecules. The fluorescence intensity of BSA decreased gradually, as the concentration of the four polyphenols increased. The polyphenols were interacted with BSA to make more tyrosine or tryptophan exposure, eventually resulting in the lower fluorescence intensity. There was the fluorescence spectroscopy maximum wavelength redshift EGCG>PC, C>TP (365 nm>364 nm, 364 nm>363 nm). Fluorescence spectrum indicated the static quenching of all four types of polyphenols to BSA. The rate constant of protein quenching of polyphenols was 1013 at temperatures of 290 and 300 K. The Ksv of EGCG-BSA decreased most outstandingly, when the temperature increased. The catechol structure in the EGCG molecule was broken or deformed at high temperature. The binding constant KA with temperature was the same as the quenching constant Ksv . The higher the temperature was, the smaller the binding constant KA was. All level 10³ demonstrated the weak interaction force between the four polyphenols and BSA. The binding site n was about 1, indicating the presence of a binding site. The fluorescence intensity of BSA gradually decreased with the concentration of the four polyphenols increased. Therefore, both polyphenols were interacted with BSA to make more tyrosine or tryptophan exposure, eventually resulting in lower fluorescence intensity. The infrared spectroscopy indicated that four polyphenols altered the secondary structure of BSA, and then promoted the protein structure stabilization. Amide I band absorption peak (1 657.44 cm−1) occurred the blue-shifted PC>TP>EGCG>C (1 656.15 cm−1>1 632.07 cm−1>1 631.49 cm−1 > 1 631.44 cm−1). Nicotinamide II band peak shape was widening. The hydrogen bond of the BSA increased after the interaction. After the addition of TP, PC, and C, the BSA secondary structure was changed from β-turn, random coil to β-sheet, ɑ-helix, and the relative content of β-sheet, ɑ-helix increases, indicating the enhanced compactness of BSA conformation. Specifically, β -sheet content increased in the order of C-BSA (40.20%)>PC-BSA (39.50%)>EGCG-BSA (39.32%)>TP-BSA (34.04%), indicated that the C was better promoted the secondary structure stability of BSA. Molecular docking results indicated that the binding site was located in the hydrophobic cavity of Sub-domain IIA. Intermolecular interaction forces were mainly hydrogen bonding, and hydrophobic forces, in the order of the Binding energy C (−3.72 kJ/ mol)

Ribociclib (RIB), a tyrosine kinase inhibitor, exhibits promising antitumor efficacy and controlled toxicity in HR+/HER2- breast cancer patients, which is closely related to the binding with plasma proteins. This study utilized a combination of spectroscopic techniques including UV spectroscopy, fluorescence spectroscopy, and circular dichroism (CD) as well as molecular docking and molecular dynamic simulation to clarify the binding mechanism between bovine serum albumin (BSA) and RIB. The findings demonstrated that RIB produced a 1:1 stoichiometric complex with BSA, which quenched BSA's fluorescence in the manner of the static quenching mechanism. Site labelling experiments pinpointed Site III on BSA as the primary binding site for RIB, a finding validated by molecular docking. Van der Waals forces and hydrogen bonding interactions as key drivers in the formation of RIB-BSA complexes, a conclusion supported by molecular docking. Molecular simulation studies suggested that the insertion of RIB into the hydrophobic cavity (Site III) of BSA induced subtle conformational changes in the BSA protein, and CD measurements confirmed alterations in BSA secondary structure content. Synchronous and three-dimensional fluorescence spectroscopy further demonstrated that RIB decreased the hydrophobicity of the microenvironment surrounding tyrosine and tryptophan residues. These findings offer valuable insights into the pharmacokinetics and structural modifications of RIB. • RIB inserts preferentially into the hydrophobic cavity on subdomains Site III of BSA. • Ribociclib reduced the hydrophobicity of the microenvironment of aromatic amino acid residues in BSA. • Hydrogen bonding, van der Waals force and hydrophobic interaction are the main forces that bind RIB to BSA. • The contribution of key residues to the stability of RIB-BSA system was discussed. [ABSTRACT FROM AUTHOR]

Copyright of Food Research & Development is the property of Food Research & Development Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The objective of this paper was to study in vitro the complexing ability of anionic polyelectrolyte in relation to model protein to develop a new type of polymeric feed additive for agricultural animals. It has been established that the investigated polymer with a molecular weight of 1 × 10 forms interpolymer complexes with model protein, namely, bovine serum albumin (BSA). The degree of the formation of these complexes significantly depends on the acidity of the medium and the ratio of components. It has been established that these complexes are formed in a wide interval of the ratio of components, i.e., both in the excess of protein in relation to polymer and in the excess of polymer in relation to protein. It has been revealed that 2.0-2.5% of BSA is complexed under conditions that are similar to the conditions of ruminant forestomachs at reaction medium pH 5.0-6.5 and a polymer-to-protein weight ratio of approximately 0.3 × 10. [ABSTRACT FROM AUTHOR]

A calcium-binding peptide was isolated from the hydrolysates of bovine serum protein (BSP). BSP was hydrolyzed using 3 different types of proteases, Alcalase, Flavourzyme, and Protamex, and the degree of hydrolysis was determined and monitored using trinitrobenzenesulfonic acid and SDS-PAGE. The hydrolysates of BSP using Alcalase were selected and ultra-filtered below 3 kDa. The membrane-filtered solution was then fractionated using ion exchange chromatography and normal phase HPLC to isolate a calcium-binding peptide. The calcium-binding capacity was determined by the orthophenanthroline method. The sequence of the purified calcium-binding peptide was analyzed using LC/electron spray ionization (LC/ESI)-tandem mass spectroscopy and identified to be Asp-Asn-Leu-Pro-Asn-Pro-Glu-Asp-Arg-Lys-Asn-Tyr-Glu, which has a molecular weight of 1,603 Da. [ABSTRACT FROM AUTHOR]

The application of protein-based bioactive molecule complexes is limited by their instability under environmental conditions, such as pH, ionic strength, and ultraviolet irradiation. In this study, Bovine serum albumin (BSA) and BSA-glucose conjugates (GBSA) with different glycated extent were complexed with resveratrol (RES). Formation of the BSA/GBSA-RES nanocomplexes was confirmed by UV–visible spectroscopy. Fluorescence quenching spectra indicated that the BSA-RES and GBSA-RES nanocomplexes were formed via noncovalent interactions by a self-assembly method. Interestingly, BSA with a greater glycation extent showed a higher binding affinity for RES. Compared with BSA/GBSA I (BSA glycated in water system)-RES, the GBSA II (BSA glycated in natural deep eutectic solvent system)-RES nanocomplex obtained highest Z-average diameter, encapsulation efficiency and loading capacity. Fourier transform infrared and X-ray diffraction spectra indicated that RES was complexed with BSA/GBSA in an amorphous form. Compared with BSA-RES nanocomplexes, GBSA-RES (particularly GBSA II) nanocomplexes showed better environmental stress (ionic strength, heat, and pH) and storage stability. The advantages of the glycated proteins may provide an effective alternative to protect and deliver bioactive compounds in the food and pharmaceutical industries. [Display omitted] • BSA-RES and GBSA-RES nanocomplexes were formed via noncovalent interactions. • RES complexed with BSA/GBSA using a self-assembly method. • Higher extent of BSA glycation signified a stronger binding affinity for RES. • Increased binding affinity enhanced the physicochemical stability of nanocomplexes. [ABSTRACT FROM AUTHOR]

[Display omitted] • BSA and BSA-glucose conjugates (GBSA) complexed with curcumin (CUR) were fabricated. • The interaction of CUR and BSA or GBSA was spontaneous. • BSA/GBSA–CUR nanocomplexes were formed mainly by hydrophobic interactions. • Increasing the extent of glycation promoted physicochemical stability of nanocomplexes. Bovine serum albumin (BSA) and BSA-glucose conjugates (GBSAⅠ and GBSAⅠI) with different extent of glycation were complexed with curcumin (CUR). The formation mechanism of BSA/GBSA-CUR complexes and the effect of glycation on their physicochemical properties were investigated. Fluorescence quenching and FTIR analysis indicated that the BSA/GBSA–CUR nanocomplexes were formed mainly by hydrophobic interactions. XRD analysis demonstrated that CUR was present in an amorphous state in the nanocomplexes. BSA with a greater extent of glycation (BSA < GBSAⅠ

Washing and lysing monolayer cells directly from cell culture plasticware is a commonly used method for protein extraction. We found that multiple protein bands were enriched in samples with low cell numbers from the 6-well plate cultures. These proteins contributed to the overestimation of cell proteins and led to the uneven protein loading in Western blotting analysis. In Coomassie blue stained SDS-PAGE gels, the main enriched protein band is about 69 kDa and it makes up 13.6% of total protein from 10 4 U251n cells. Analyzed by mass spectrometry, we identified two of the enriched proteins: bovine serum albumin and bovine serum transferrin. We further observed that serum proteins could be extracted from other cell culture plates, dishes and flasks even after washing the cells 3 times with PBS. A total of 2.3 mg of protein was collected from a single well of the 6-well plate. A trace amount of the protein band was still visible after washing the cells 5 times with PBS. Thus, serum proteins should be considered if extracting proteins from plasticware, especially for samples with low cell numbers.