Far-Red Emission of mPlum Fluorescent Protein Results from Excited-State Interconversion between Chromophore Hydrogen-Bonding States

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• 作者：Eunjin Yoon ; Patrick E. Konold ; Junghwa Lee ; Taiha Joo ; Ralph Jimenez
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2016
• 出版时间：June 16, 2016
• 年：2016
• 卷：7
• 期：12
• 页码：2170-2174
• 全文大小：280K
• 年卷期：0
• ISSN：1948-7185

文摘

Fluorescent proteins with large Stokes shifted emission beyond 600 nm are actively sought for live-cell imaging applications. The mechanism of excited-state relaxation leading to the Stokes shift in the mPlum fluorescent protein, which emits at a peak wavelength of 650 nm, has been previously investigated by both ultrafast spectroscopy and theoretical methods. Here, we report that femtosecond time-resolved area-normalized emission spectra of mPlum show a clear isoemissive point. This feature can only result from a system with two emitting states, rather than a system that undergoes a continuous spectral red shift, for example, as expected from typical solvation. Global analysis of the femtosecond time-resolved fluorescence spectra reveals time constants associated with chromophore relaxation, excited-state population transfer, and an excited-state lifetime of the final state. The observations confirm the findings of recent quantum chemical calculations on mPlum.