Protein folding--what's the question?
The folding reactions of many small, globular proteins exhibit two-state kinetics, in which the folded and unfolded states interconvert readily without observable intermediates. Typically, the free energy difference, delta G, between the native and denatured states of such a protein is quite small, lying in the range of approximately -5 to -15 kcal/mol. We point out that, under these circumstances, a population of native-like molecules will persist, even in the presence of mutations sufficiently destabilizing to change the sign of delta G. Therefore, it is not energy per se that determines conformation. A corollary to this argument is that specificity--not stability--would be the more informative focus in future folding studies.
Lattman
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Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
Rose
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GD
D011487:Protein Conformation; D017510:Protein Folding; D013237:Stereoisomerism; D013816:Thermodynamics