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Long-lived amide I vibrational modes in myoglobin.
A Xie1, L van Der Meer, W Hoff
1Department of Physics, Oklahoma State University, Stillwater, Oklahoma 74708, USA.
Physical Review Letters
|September 16, 2000
Summary
Protein alpha helices can support long-lived nonlinear states. Infrared pump-probe spectroscopy revealed that myoglobin
Area of Science:
- Biophysics
- Protein Dynamics
- Spectroscopy
Background:
- Vibrational relaxation rates are measured using infrared pump-probe spectroscopy.
- Myoglobin is a protein primarily composed of alpha-helical structures.
Purpose of the Study:
- Investigate excited state relaxation dynamics in myoglobin.
- Determine if protein secondary structure influences relaxation.
- Characterize nonlinear states in protein dynamics.
Main Methods:
- Infrared pump-probe spectroscopy.
- Optical pumping at 5.85 micrometers (amide I band).
- Comparative analysis of myoglobin, alanine, and photoactive yellow protein.
Main Results:
- Myoglobin exhibits unusually long, nonexponential excited state relaxation.
- Alanine and beta-sheet rich photoactive yellow protein lack this long-lived state.
- Nonlinear states with characteristic times of 15 ps were observed.
Conclusions:
- The alpha-helical structure in proteins can support long-lived nonlinear states.
- Protein secondary structure plays a significant role in excited state relaxation dynamics.
- These findings offer insights into protein energy dissipation mechanisms.