Hydrated Myoglobin's Anharmonic Fluctuations are not Primarily due to Dihedral Transitions

To characterize the functionally important anharmonic motions of proteins, simulations of carboxymyoglobin (MbCO) dynamics have been performed during which dihedral transitions were prohibited. Comparison of torsionally restrained and unrestrained protein dynamics simulated at three levels of hydrat...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 1996-01, Vol.93 (1), p.55-59
Main Authors: Steinbach, Peter J., Brooks, Bernard R.
Format: Article
Language:English
Subjects:
Atoms
Biology
Biophysical Phenomena
Biophysics
Center of mass
Computer Simulation
Contrapuntal motion
Cooling
Kinetics
Mathematical minima
Molecules
Motion
Myoglobin - chemistry
Myoglobins
Physics
Proteins
Statistical variance
Temperature
Temperature dependence
Transition temperature
Water
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Summary:To characterize the functionally important anharmonic motions of proteins, simulations of carboxymyoglobin (MbCO) dynamics have been performed during which dihedral transitions were prohibited. Comparison of torsionally restrained and unrestrained protein dynamics simulated at three levels of hydration and at temperatures ranging from 100 to 400 K suggests that hydration ``catalyzes'' protein mobility by facilitating collective anharmonic motions that do not require dihedral transitions. When dihedral transitions were prohibited, dehydrated MbCO, to a good approximation, exhibited only harmonic fluctuations, whereas hydrated MbCO exhibited both harmonic and anharmonic motions. The fluctuation of helix centers of mass also remained highly anharmonic in the torsionally restrained hydrated system. Atomic mean-square fluctuation at 300 K was reduced upon prohibition of dihedral transitions by only 28% and 10% for MbCO hydrated by 350 and 3830 water molecules, respectively.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.93.1.55