Unfolding/refolding studies of the myosin rod

Abstract

The effect of guanidine hydrochloride on the gel‐filtration chromatography, viscosity, far ultraviolet circular dichroism and fluorescence emission intensity of the myosin rod was studied under equilibrium conditions. The normalized transition curves for each of these methods were comparable with a midpoint at a guanidine hydrochloride concentration of 1.75–2 M. The curves were not, however, superposable, suggesting that the loss of helix content and the dissociation of the two chains of the myosin rod were not tightly linked. Furthermore, they were unexpectedly independent of the protein concentration over 0.05–20 μM. These phenomena are interpreted taking into account the large size of the molecule. A step‐wise process is proposed as a model for the unfolding of the myosin rod. Copyright © 1993, Wiley Blackwell. All rights reserved