Ultrafast electronic and vibrational dynamics of stabilized A state mutants of the green fluorescent protein (GFP): Snipping the proton wire

Deborah Stoner-Ma, Andrew A. Jaye, Kate L. Ronayne, Jerome Nappa, Peter J. Tonge, Stephen R. Meech

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Two blue absorbing and emitting mutants (S65G/T203V/E222Q and S65T at pH 5.5) of the green fluorescent protein (GFP) have been investigated through ultrafast time resolved infra-red (TRIR) and fluorescence spectroscopy. In these mutants, in which the excited state proton transfer reaction observed in wild-type GFP has been blocked, the photophysics are dominated by the neutral A state. It was found that the A* excited state lifetime is short, indicating that it is relatively less stabilised in the protein matrix than the anionic form. However, the lifetime of the A state can be increased through modifications to the protein structure. The TRIR spectra show that a large shifts in protein vibrational modes on excitation of the A state occurs in both these GFP mutants. This is ascribed to a change in H-bonding interactions between the protein matrix and the excited state.
Original languageEnglish
Pages (from-to)193-200
Number of pages8
JournalChemical Physics
Issue number1-3
Publication statusPublished - 20 Feb 2008

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