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Proton Transfer and Protein Conformation Dynamics in Photosensitive Proteins by Time-resolved Step-scan Fourier-transform Infrared Spectroscopy
Published on: June 27, 2014
Mapping GFP structure evolution during proton transfer with femtosecond Raman spectroscopy
Chong Fang1, Renee R Frontiera, Rosalie Tran
1Department of Chemistry, University of California, Berkeley, California 94720, USA.
Nature
|November 13, 2009
Summary
Femtosecond stimulated Raman spectroscopy reveals atomic motions in green fluorescent protein (GFP). This technique tracks skeletal motions during excited-state proton transfer (ESPT), crucial for GFP
Area of Science:
- Chemical Physics
- Biophysics
- Spectroscopy
Background:
- Understanding atomic motions in chemical reactions requires high-resolution, time-resolved structural data.
- Complex biological transformations, like those in green fluorescent protein (GFP), remain challenging to study at the atomic level.
- The mechanism of excited-state proton transfer (ESPT) in GFP, responsible for its bioluminescence, is not fully understood.
Purpose of the Study:
- To elucidate the atomistic details of excited-state proton transfer (ESPT) in green fluorescent protein (GFP).
- To investigate the real-time nuclear dynamics governing the fluorescent properties of GFP.
- To demonstrate the utility of femtosecond stimulated Raman spectroscopy for studying complex chemical transformations.
Main Methods:
- Utilized femtosecond stimulated Raman spectroscopy (FSRS) to obtain time-resolved vibrational spectra.
- Focused on the electronically excited chromophore of GFP.
- Analyzed marker bands (C-O and C=N stretching modes) to track atomic motions.
Main Results:
- Observed out-of-phase oscillations of C-O and C=N stretching modes with a 280 fs period.
- Attributed these oscillations to impulsively excited phenoxyl-ring motions.
- These motions were found to optimize chromophore geometry for ESPT.
Conclusions:
- Femtosecond stimulated Raman spectroscopy provides detailed insights into the nuclear dynamics of ESPT in GFP.
- Low-frequency phenoxyl-ring motions play a critical role in facilitating proton transfer.
- FSRS is a powerful tool for mapping multidimensional reaction coordinates in real-time.
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