A Dilatometric Study of the Denaturation of Lysozyme by Guanidine Hydrochloride and Hydrochloric Acid

The denaturation of lysozyme by guanidine hydrochloride and hydrochloric acid, and by guanidine hydrochloride alone at 25 °C was studied using a dilatometric technique. From results of the dilatometric measurements volume changes for partial and complete denaturation by hydrochloric acid at constant guanidine hydrochloride concentration were determined. The volume change due to unfolding per se in 3 M guanidine hydrochloride was found to be — 47 ml per mol of lysozyme. Volume changes were also determined for partial and complete denaturation of lysoyzme at 25 °C by guanidine hydrochloride alone at constant pH. The volume change due to unfolding per se in 6 M guanidine hydrochloride and pH 5.2 was determined to be — 54 ml per mol of lysozyme.