Dynamics of a small globular protein in terms of low-frequency vibrational modes.
Normal modes of low-frequency vibrations are calculated for a small globular protein, bovine pancreatic trypsin inhibitor. In modes with frequencies below 120 cm-1 the protein molecule behaves like a continuous elastic body. Most modes with frequencies above 50 cm-1 are shown to behave harmonically within the range of thermal fluctuations at room temperature. Those with frequencies below 50 cm-1 show some anharmonicity. Magnitudes of displacements of atoms are mainly determined by the modes with frequencies below 30 cm-1. These very-low-frequency modes contribute significantly to the entropy of the system. The dynamic structure of the globular protein is described as a superposition of harmonic high-frequency motions and coupled anharmonic low-frequency motions of collective variables corresponding to the normal modes of vibration.
D000818:Animals; D002417:Cattle; D004548:Elasticity; D008958:Models, Molecular; D011487:Protein Conformation; D014359:Trypsin Inhibitor, Kazal Pancreatic; D014361:Trypsin Inhibitors; D014732:Vibration
D014361:Trypsin Inhibitors; D014359:Trypsin Inhibitor, Kazal Pancreatic