Low-frequency vibrations of helical structures in protein molecules.

A physically intuitive and mathematically easily handled formula is presented for calculating the low-frequency vibrations of helical structures in protein molecules. alpha-Chymotrypsin is taken as an example, and the calculated result shows precise agreement with observations of the low-frequency Raman spectra. As reflected in the formula, this kind of low frequency is very sensitive to the conformation of a biomacromolecule, and can therefore serve as a vehicle to investigate the mechanism of action of a biomacromolecule from the viewpoint of dynamics. On this basis a feasible experiment is suggested by which one can examine the relationship between a presumed mode of low-frequency vibration in a biomacromolecule and its activity.