Abstract

The dynamical behavior of proteins is often interpreted in terms of conformational substates.¹ A protein can assume a large number of slightly different structures, separated by conformational barriers. This view is very similar to the description of glass dynamics in terms of two-level systems.²,³ A two-level system (TLS) represents a group of atoms or molecules which can reside in either of two potential energy wells along a conformational coordinate. At very low temperature the TLS can fluctuate between the two potential energy minima through a tunneling process.

© 1994 Optical Society of America