Dynamics of Protein and Chromophore Structural Changes in the Photocycle of Photoactive Yellow Protein Monitored by Time-Resolved Optical Rotatory Dispersion

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• 作者：Eefei Chen ; Thomas Gensch ; Andrew B. Gross ; Johnny Hendriks ; Klaas J. Hellingwerf ; and David S. Kliger
• 刊名：Biochemistry
• 出版年：2003
• 出版时间：February 25, 2003
• 年：2003
• 卷：42
• 期：7
• 页码：2062 - 2071
• 全文大小：124K
• 年卷期：v.42,no.7(February 25, 2003)
• ISSN：1520-4995

文摘

The dynamics of the PYP photocycle have been studied using time-resolved optical rotatorydispersion (TRORD) spectroscopy in the visible and far-UV spectral regions to probe the changes in thechromophore configuration and the protein secondary structure, respectively. The changes in the secondarystructure in PYP upon photoisomerization of the chromophore can be described by two exponential lifetimesof 2 ± 0.8 and 650 ± 100 ms that correspond to unfolding and refolding processes, respectively. TheTRORD experiments that follow the dynamics of the chromophore report three exponential components,with lifetimes of 10 ± 3 s, 1.5 ± 0.5 ms, and 515 ± 110 ms. A comparison of the kinetic behaviors ofthe chromophore and protein shows that during the decay of pR₄₆₅ an initial relaxation that is localizedto the chromophore hydrophobic pocket precedes the formation of the chromophore and protein structuresfound in pB₃₅₅. In contrast, the protein and chromophore processes occur with similar time constantsduring inactivation of the signaling state.