期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2018
卷号：115
期号：35
页码：8671-8675
DOI：10.1073/pnas.1806491115
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Photoactive yellow protein (PYP), from the phototrophic bacterium Halorhodospira halophila , is a small water-soluble photoreceptor protein and contains p -coumaric acid ( p CA) as a chromophore. PYP has been an attractive model for studying the physical chemistry of protein active sites. Here, we explore how Raman optical activity (ROA) can be used to extract quantitative information on distortions of the p CA chromophore at the active site in PYP. We use 13C8- p CA to assign an intense signal at 826 cm−1 in the ROA spectrum of PYP to a hydrogen out-of-plane vibration of the ethylenic moiety of the chromophore. Quantum-chemical calculations based on density functional theory demonstrate that the sign of this ROA band reports the direction of the distortion in the dihedral angle about the ethylenic C=C bond, while its amplitude is proportional to the dihedral angle. These results document the ability of ROA to quantify structural deformations of a cofactor molecule embedded in a protein moiety.
关键词：photoreceptor ; chromophore ; vibrational spectroscopy ; density functional theory ; molecular strain
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