| dc.description.abstract | In this study, the orientation and conformation change of protein hydrophobic adsorption were examined. There were three proteins been chosen, which were BAA, BSA and Lysozyme. The quartz surface was modified by octadecyltrimethoxysilane to form the hydrophobic surface. At first, according to the tryptophan fluorescence spectrum analysis, the intensity of tryptophan in polar environment was higher than nonpolar environment and the wavelength of lambda maximum was blue shift when tryptophan located in nonpolar environment. In the experiment of Lysozyme hydrophobic adsorption, it can be found that the structure of Lysozyme on ODS surface did not change obviously in phosphate buffer. The signal of tryptophan was quenched slowly as time increase, we could infer that Lysozyme adsorbed firstly by Try123 at α-Domain and then adsorbed gradually by Trp62 and Trp63 at β-Domain. However, when protein solution contained DL-Dithiothreitol, we could obtain that the intensity of lambda 340nm increased and the lambda maximum was red shift. These indicated that the protein structure was changed because of the disulfide bonds were broken which caused that Trp28 and Trp108 exposed outside the protein surface and oriented to polar environment. In the experiment of BSA, we found that when BSA adsorbed on ODS surface the wavelength was blue shift from 340nm to 310nm then gradually red shift to 325nm. We thought that BSA was adsorbed by Trp158 located at IB-domain firstly then forced the I domain and II domain of BSA changed the direction gradually, and the fluorescence of tryptophan was almost disappear after adsorption. Finally, in BAA hydrophobic adsorption experiment, we found that the intensity of 340nm was decrease due to tryptophan be quenched and the lambda maximum was no change which indicated that the native structure of BAA was still maintains on the ODS surface. Furthermore, by calculating the quench ratio of BAA, we could conjecture that the orientation was the plane of BAA which contained seven tryptophan. In consequence, the conformation change and orientation surmise of protein hydrophobic adsorption can be obtained via the fluorescence spectrum analysis directly. | en_US |