Direct access to the cooperative substructure of proteins and the protein ensemble via cold denaturation.
The modern view of protein thermodynamics predicts that proteins undergo cold-induced unfolding. Unfortunately, the properties of proteins and water conspire to prevent the detailed observation of this fundamental process. Here we use protein encapsulation to allow cold denaturation of the protein ubiquitin to be monitored by high-resolution NMR at temperatures approaching -35 degrees C. The cold-induced unfolding of ubiquitin is found to be highly noncooperative, in distinct contrast to the thermal melting of this and other proteins. These results demonstrate the potential of cold denaturation as a means to dissect the cooperative substructures of proteins and to provide a rigorous framework for testing statistical thermodynamic treatments of protein stability, dynamics and function.
Johnson Research Foundation and Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6059, USA.
Charles R
CR
Babu
Vincent J
VJ
Hilser
A Joshua
AJ
Wand
D000465:Algorithms; D003080:Cold Temperature; D005615:Freezing; D009682:Magnetic Resonance Spectroscopy; D008823:Micelles; D008958:Models, Molecular; D011487:Protein Conformation; D011489:Protein Denaturation; D011506:Proteins / Q000737:chemistry*; D025801:Ubiquitin / Q000737:chemistry* / Q000378:metabolism
D008823:Micelles; D011506:Proteins; D025801:Ubiquitin