TEMPERATURE QUENCH ECHOES IN PROTEINS

Temperature quench echoes are analyzed in terms of the temperature-tem perature correlation function in the harmonic approximation, and the r esulting expressions are compared with molecular dynamics simulations. The relationship between the time dependence of the echo depth and th e density of states is demonstrated for harmonic systems. For a protei n, which has significant anharmonicity, the time dependence is dominat ed by relaxation effects that originate from dephasing of the periodic motions. A simple relaxation model is shown to provide a good descrip tion of the results observed in the simulations. (C) 1995 American Ins titute of Physics.