Abstract

Large amplitude motions in proteins and biopolymers is a fundamental feature of the biological function of these systems. The mechanism of energy transduction from a stimulus, such as ligand binding or dissociation, to a specific protein motion associated with biological function remains a controversial issue. Large amplitude motions often involve the correlated action of a vast number of vibrational modes and energy must be directed along specific channels in order to displace a sizable number of atoms. This motion must involve energy delocalization, either over a specific vibrational coordinate as postulated by the soliton model,¹ or as delocalized potential energy gradients, such as in the strain model.² These two possible mechanisms can be distinguished by the spatial dispersion of vibrational energy and the lifetimes of the vibrational modes that couple to the correlated motion. This problem can be ideally studied using transient grating spectroscopy by taking advantage of the high sensitivity and time resolution of this technique to density changes.

© 1990 Optical Society of America