Dynamical transition in proteins and non-Gaussian behavior of low-frequency modes in self-consistent normal mode analysis.
Phys Rev E Stat Nonlin Soft Matter Phys
; 82(4 Pt 1): 041917, 2010 Oct.
Article
em En
| MEDLINE
| ID: mdl-21230323
ABSTRACT
Self-consistent normal mode analysis (SCNMA) is applied to heme c type cytochrome f to study temperature-dependent protein motion. Classical normal mode analysis assumes harmonic behavior and the protein mean-square displacement has a linear dependence on temperature. This is only consistent with low-temperature experimental results. To connect the protein vibrational motions between low and physiological temperatures, we have incorporated a fitted set of anharmonic potentials into SCNMA. In addition, quantum harmonic-oscillator 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 that it may be the cause of the non-Gaussian behavior of the protein motions probed by elastic incoherent neutron scattering. The combined theory displays a dynamical transition caused by the softening of few "torsional" modes in the low-frequency regime ( <50 cm(-1) or <6 meV or >0.6 ps). 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.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Citocromos f
/
Modelos Biológicos
Idioma:
En
Revista:
Phys Rev E Stat Nonlin Soft Matter Phys
Assunto da revista:
BIOFISICA
/
FISIOLOGIA
Ano de publicação:
2010
Tipo de documento:
Article
País de afiliação:
Estados Unidos