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He Z.-D.,Shenzhen University | Zhou K.,Shenzhen Marine Environment and Resource Monitoring Center
Journal of Luminescence | Year: 2014

The interaction of Ligupurpuroside A with bovine serum albumin (BSA) has been investigated by fluorescence spectra, UV-vis absorption spectra, three-dimensional (3D) fluorescence spectra, synchronous fluorescence spectra and circular dichroism (CD) spectra along with a molecular docking method. The fluorescence experiments indicate that Ligupurpuroside A can quench the intrinsic fluorescence of BSA through a combined quenching way at the low concentration of Ligupurpuroside A, and a static quenching procedure at the high concentration. The thermodynamic analysis suggests that hydrogen bonds and van der Waals forces are the main forces between BSA and Ligupurpuroside A. According to the theory of Försters non-radiation energy transfer, the binding distance between BSA and Ligupurpuroside A was calculated to be 2.73 nm, which implies that energy transfer occurs between BSA and Ligupurpuroside A. All these experimental results have been validated by the protein-ligand docking studies which show that Ligupurpuroside A binds to the residues located in the hydrophobic cavity on subdomain IIA of BSA. In addition, conformation change of BSA was observed from three-dimensional fluorescence spectra, synchronous fluorescence spectra and circular dichroism spectra under experimental conditions. © 2014 Elsevier B.V. Source


Shen L.-L.,Shenzhen University | Zhu Q.-Q.,Shenzhen University | Huang F.-W.,Shenzhen University | Xu H.,Shenzhen University | And 8 more authors.
LWT - Food Science and Technology | Year: 2015

Circular dichroism spectra, fluorescence spectra, synchronous fluorescence spectra, resonance light scattering spectra, ELISA experiments, along with bioinformatics method have been used to study the relationship between immunogenicity and structure of recombinant peanut protein Ara h 2.01 with increase in temperature. The experimental results show that the protein collapses gradually within the temperature range from room temperature to 100°C, and the collapse reaches saturation at around 100°C, while its secondary structures remain almost the same, and its immunogenicity decreases steadily over the experimental temperature range. These research results can be explained reasonably by its advanced structure and epitopes predicted by bioinformatics, and should be helpful to the further understanding of the sensitization mechanism of food allergen and the guidance of peanut food processing. © 2014 Elsevier Ltd. Source


Ying M.,Shenzhen University | Huang F.,Shenzhen University | Ye H.,Shenzhen University | Xu H.,Shenzhen University | And 9 more authors.
International Journal of Biological Macromolecules | Year: 2015

The interaction between curcumin and pepsin was investigated by fluorescence, synchronous fluorescence, UV-vis absorption, circular dichroism (CD), and molecular docking. Under physiological pH value in stomach, the fluorescence of pepsin can be quenched effectively by curcumin via a combined quenching process. Binding constant (Ka) and binding site number (n) of curcumin to pepsin were obtained. According to the theory of Förster's non-radiation energy transfer, the distance r between pepsin and curcumin was found to be 2.45nm within the curcumin-pepsin complex, which implies that the energy transfer occurs between curcumin and pepsin, leading to the quenching of pepsin fluorescence. Fluorescence experiments also suggest that curcumin is located more closely to tryptophan residues than tyrosine residues. CD spectra together with UV-vis absorbance studies show that binding of curcumin to pepsin results in the extension of peptide strands of pepsin with loss of some β-sheet structures. Thermodynamic parameters calculated from the binding constants at different temperatures reveal that hydrophobic force plays a major role in stabilizing the curcumin-pepsin complex. In addition, docking results support the above experimental findings and suggest the possible hydrogen bonds of curcumin with Thr-77, Thr-218, and Glu-287 of pepsin, which help further stabilize the curcumin-pepsin complex. © 2015 Elsevier B.V. Source


Fang Y.,Shenzhen University | Xu H.,Shenzhen University | Shen L.,Shenzhen University | Huang F.,Shenzhen University | And 8 more authors.
Luminescence | Year: 2015

The interaction of acteoside with pepsin has been investigated using fluorescence spectra, UV/vis absorption spectra, three-dimensional (3D) fluorescence spectra and synchronous fluorescence spectra, along with a molecular docking method. The fluorescence experiments indicate that acteoside can quench the intrinsic fluorescence of pepsin through combined quenching at a low concentration of acteoside, and static quenching at high concentrations. Thermodynamic analysis suggests that hydrogen bonds and van der Waal's forces are the main forces between pepsin and acteoside. According to the theory of Förster's non-radiation energy transfer, the binding distance between pepsin and acteoside was calculated to be 2.018 nm, which implies that energy transfer occurs between acteoside and pepsin. In addition, experimental results from UV/vis absorption spectra, 3D fluorescence spectra and synchronous fluorescence spectra imply that pepsin undergoes a conformation change when it interacts with acteoside. © 2015 John Wiley Sons, Ltd. Source

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