The interaction between Xanthan Gum and Bovine Serum Albumin was studied by Multispectral Method and Molecular Docking Simulation

Abstract

Abstract Xanthan gum (XG) is a kind of biological macromolecular drug, which is widely used in the field of biomedicine. Bovine serum albumin is very similar to human serum albumin, and it is easy to extract and cheap, so it is often used to study the interaction with drugs. However, due to the structural complexity of xanthan gum, the interaction of xanthan gum with bovine serum albumin (BSA) and its effects on its secondary structure and mechanism are less studied.In this paper, a variety of spectroscopy and molecular docking will be used to systematically study the interaction mechanism of XG and BSA. On this basis, the interaction and quenching mode between XG and BSA were determined. The intrinsic fluorescence which can effectively quench BSA is obtained by fluorescence spectrum analysis, and the dynamic quenching rate at different temperatures is much higher than the maximum diffusion collision quenching constant, so it can be known that XG interacts with BSA. The quenching constant is solved by Stern-Volmer equation. When the temperature is different, With the increase of temperature, the quenching constant of XG and BSA system decreases, so it can be judged that the quenching method of XG on BSA is static quenching. According to the Vant's Hoff equation, the thermodynamic parameters Δ H < 0 and Δ S < 0 between XG and BSA are mainly hydrogen bond and van der Waals force. If Δ G < 0 and Δ H < 0, it is proved that the quenching process of XG and BSA is spontaneous and exothermic. The molecular docking simulation results show that hydrogen bond and van der Waals force are the main forces between XG and BSA, which is consistent with thermodynamic results, indicating that XG changes the secondary structure of BSA.Through the multi-spectral analysis, it is known that due to the influence of the microenvironment, the polarity and hydrophilicity of XG and BSA are enhanced, and the hydrophobicity is weakened, resulting in changes in the secondary structure of BSA. In the binding distance between XG and BSA, there is an overlap between the fluorescence emission spectrum of BSA and the UV-vis absorption spectrum of XG, which proves that there is energy transfer between BSA and XG, and then the overlap integral is calculated that r is significantly smaller than 7nm, this indicates that there is non-radiative energy transfer between XG and BSA. The results of circular dichroism spectra show that BSA is mainly β-fold. indicating that XG interacts with BSA, and some proteins are loosened, resulting in the decrease of α-Helix structure and the increase of β-sheet structure, which further proves that the secondary structure of BSA has changed. Through the study of the interaction between XG and BSA, the interaction mechanism of both is analyzed by spectroscopy and molecular docking simulation technology, which provides data support for their future discussion and research.