Stability and dynamics in a hyperthermophilic protein with melting temperature close to 200°C

^*The Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6059; and ^‡Department of Biochemistry and Molecular Biology and the Center for Metalloenzyme Studies, University of Georgia, Athens, GA 30602

Contributed by S. Walter Englander

Abstract

The rubredoxin protein from the hyperthermophilic archaebacterium Pyrococcus furiosus was examined by a hydrogen exchange method. Even though the protein does not exhibit reversible thermal unfolding, one can determine its stability parameters—free energy, enthalpy, entropy, and melting temperature—and also the distribution of stability throughout the protein, by using hydrogen exchange to measure the reversible cycling of the protein between native and unfolded states that occurs even under native conditions.

Footnotes

↵ † Present address: Department of Physiology and Pharmacology, Sacler School of Medicine, University of Tel Aviv, Tel Aviv 69978, Israel.
↵ § To whom reprint requests should be addressed. e-mail: Walter{at}HX2.Med.UPenn.Edu.
ABBREVIATIONS:

RdPf,

the rubredoxin protein from Pyrococcus furiosus;

HX,

hydrogen exchange;

GdmCl,

guanidinium chloride