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Proton shuttle in green fluorescent protein studied by dynamic simulations
Markus A Lill1, Volkhard Helms
1Max Planck Institute of Biophysics, Kennedyallee 70, 60596 Frankfurt, Germany.
Summary
Green fluorescent protein (GFP) proton transfer occurs in ultrafast steps, simulated in atomic detail. This research reveals distinct pathways for forward and backward proton movement, offering new insights into GFP
Area of Science:
- Biophysics
- Computational Chemistry
- Molecular Biology
Background:
- Green fluorescent protein (GFP) exhibits proton transfer crucial for its function.
- Understanding excited-state proton transfer (ESPT) mechanisms is key to protein fluorescence.
- The A and I forms of GFP involve complex proton relay dynamics.
Purpose of the Study:
- To simulate the multistep proton transfer reaction in GFP at atomic resolution.
- To elucidate the ultrafast dynamics of proton relay shuttle between GFP forms.
- To provide atomic models and rate constants for proton transfer events.
Main Methods:
- Specialized molecular dynamics (MD) simulations.
- Direct simulation of proton transfer reactions in atomic detail.
- Analysis of femtosecond-scale dynamics.
Main Results:
- Second and third proton transfer steps occur on ultrafast timescales (tens of femtoseconds).
- Ground-state proton back-shuttle is slower and follows a different event sequence.
- Realistic rate constants for proton transfer events were determined.
Conclusions:
- Atomic models of intermediates in GFP proton transfer were generated.
- The study suggests a difference between equilibrium and intermediate I forms of GFP.
- Conformational changes, like anti to syn rotation, may distinguish GFP forms.