Investigation of the relationship between the structure of purple membrane of bacteriorhodopsin and circular dichroism spectrum
Date Issued
2014
Date
2014
Author(s)
Chou, Yu-Chun
Abstract
The bacteriorhodopins (BR) assemble into ordered two-dimensional hexagonal crystalline patches called purple membrane (PM). The circular dichroism (CD) spectra is sensitive to its conformational change, and we try to use excitonic model to investigate the relationship between the structures of PM and CD spectra to obtain more information. First, we calculate the spectra of one BR trimer with dynamic disorder and static disorder, and change the angle of transition dipole to see the variation which is determined by rotational strength of each eigenstate and the sign of coupling. We can thus probe the possible angle of transition dipoles. Second, we expand the size of the system to model aggregated PM structure, including models with 7 and 19 bR trimers, respectively. By comparing with the biphasic pattern of experimental results, we propose a PM structure in solution with new arrangement of bR trimers different from the result of x-ray crystallography. We vary the distance between bR trimers and rotate the orientations of trimers, and aim to understand the variation in CD spectra through the electronic structures. We believe our research can provide additional useful viewpoints to construct relationship between molecular structures and CD spectra in PM systems.
Subjects
視紫質
紫膜
P3 對稱性
聚集體
圓二色譜
內旋強度
Type
thesis
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