The Effect of Conjugation on the Competition between Internal Conversion and Electron Detachment: A Comparison between Green Fluorescent and Red Kaede Protein Chromophores
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- 作者：Jamie Tay ; Michael A. Parkes ; Kiri Addison ; Yohan Chan ; Lijuan Zhang ; Helen C. Hailes ; Philip C. Bulman Page ; Stephen R. Meech ; Lluís BlancafortHelen H. Fielding
- 刊名：The Journal of Physical Chemistry Letters
- 出版年：2017
- 出版时间：February 16, 2017
- 年：2017
- 卷：8
- 期：4
- 页码：765-771
- 全文大小：427K
- ISSN：1948-7185
文摘
Kaede, an analogue of green fluorescent protein (GFP), is a green-to-red photoconvertible fluorescent protein used as an in vivo “optical highlighter” in bioimaging. The fluorescence quantum yield of the red Kaede protein is lower than that of GFP, suggesting that increasing the conjugation modifies the electronic relaxation pathway. Using a combination of anion photoelectron spectroscopy and electronic structure calculations, we find that the isolated red Kaede protein chromophore in the gas phase is deprotonated at the imidazole ring, unlike the GFP chromophore that is deprotonated at the phenol ring. We find evidence of an efficient electronic relaxation pathway from higher-lying electronically excited states to the S1 state of the red Kaede chromophore that is not accessible in the GFP chromophore. Rapid autodetachment from high-lying vibrational states of S1 is found to compete efficiently with internal conversion to the ground electronic state.