Studies On The Interaction Of Essential Oil Molecules With Bovine Serum Albumin

The study on the intermolecular action between bio-active drugs and biomacromolecul--esis extremely significant to the research and development of drugs, nowadays, studies on the interaction has been widely concerned, however, the research on the interaction between essential oil molecules with bovine serum albumin has rarely been reported. In this thesis, fluorescence spectroscopy, UV-visible absorption spectroscopy, fourier transform infrared spectroscopy, raman spectroscopy and cyclic voltammetry are employed to investigate the interaction mechanism between BSA and essential oils (linalool/cinnamaldehyde/thymol), meanwhile, conformation changes of BSA induced by its interaction with small molecules are also studied, thereout, the information of essential oil molecules-BSA interaction was comprehended from molecular level, providing not only informations about intermolecular action to elucidate pharmacological mechanism of antibacterial of essential oils, but also theoretical reference for drug research and development. Main contents and results of this paper were as follows:(1) With spectral changes of essential oil molecule-BSA system, the interaction betwe--en them and conformation changes of BSA induced by small molecule were investigated by multispectroscopic and cyclic voltammetry from different angles.(2) The quenching mechanism of BSA by essential oil molecules was determined by fluorescence spectroscopy and UV-visible absorption spectroscopy. The results suggested that the fluorescence quenching of BSA by essential oil molecules were static quenching (linalool-BSA), dynamic quenching (cinnamaldehyde-BSA) and dynamic quenching (thymol-BSA) respectively, in addition, non-radioactive energy transfer between them was proved to be another reason for the quenching. Meanwhile, experimental parameters, such as binding constants, number of binding sites, binding distance and interaction force types were obtained by calculation.(3) Conformation changes of BSA caused by essential oil molecules were investigated by synchronous fluorescence spectra, IR-spectrum and raman spectra. The experimental results indicate that conformation of BSA was changed differently with its interaction with small molecules Firstly, in the system of linalool-BSA, on the one hand, the content of a-helicity of BSA decreased with others increased, on the other hand, the hydrophobicity of microenvironment of tryptophan residues and tyrosine residues both increased. Secondly, upon addition of the cinnamaldehyde to BSA the content of a-helix increased with other secondary structure decreased, besides, the hydrophobicity of microenvironment of Trp residues increased with Tyr residues decreased. Thirdly, conformation changes of BSA caused by thymol included the contents of a-helix being increased with others being decreased, moreover, the hydrophobicity of microenvironment of Trp and Tyr residues both being decreased. Finally, it was Trp/Tyr/Trp that made an important contribution to being quenched of the intrinsic fluorescence of BSA in the system of linalool-BSA, thymol-BSA, cinnamaldehyde-BSA, accordingly.