1 research outputs found
The dynamical transition in proteins and non-Gaussian behavior of low frequency modes in Self Consistent Normal Mode Analysis
Self Consistent Normal Mode Analysis (SCNMA) is applied to heme c type
cytochrome f to study temperature dependent protein motion. Classical Normal
Mode Analysis (NMA) assumes harmonic behavior and the protein Mean Square
Displacement (MSD) has a linear dependence on temperature. This is only
consistent with low temperature experimental results. To connect the protein
vibrational motions between low temperature and physiological temperature, we
have incorporated a fitted set of anharmonic potentials into SCNMA. In
addition, Quantum Harmonic Oscillator (QHO) theory has been used to calculate
the displacement distribution for individual vibrational modes. We find that
the modes involving soft bonds exhibit significant non-Gaussian dynamics at
physiological temperature, which suggests it may be the cause of the
non-Gaussian behavior of the protein motions probed by Elastic Incoherent
Neutron Scattering (EINS). The combined theory displays a dynamical transition
caused by the softening of few "torsional" modes in the low frequency regime (<
50cm-1or 0.6ps). These modes change from Gaussian to a classical
distribution upon heating. Our theory provides an alternative way to understand
the microscopic origin of the protein dynamical transition.Comment: 17 pages, 6 figures, 1 tabl