Energetic and structural consequences of
desolvation/solvation barriers to protein
folding/unfolding assessed from experimental unfolding rates
David Rodriguez-Larrea 1, Beatriz Ibarra-Molero 1 and Jose M Sanchez-Ruiz 1*
1 Universidad de Granada, Facultad de Ciencias
* To whom correspondence should be addressed. E-mail: sanchezr{at}goliat.ugr.es.
Submitted on April 27, 2006
Revised on May 22, 2006
Accepted on 19 June 2006
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Abstract |
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Theoretical work has suggested the existence of solvation/desolvation barriers in protein folding/unfolding processes. We propose that the energetic and structural consequences of such barriers for the folding transition state can be assessed from experimental unfolding rates using well-established structure-energetics relationships. For a set of proteins of size within the 60-130 number-of-residues range, we find energetic effects associated to solvation/desolvation on the order of 102 kJ/mol. This supports that the folding transition states may be characterized by large networks of water-unsatisfied, broken internal contacts. In terms of buried surface, we estimate the typical network size to be on the order of the several thousands of Å2 or, roughly, about 50% of the total change in accessible surface area upon unfolding. The analyses reported here thus suggest a clear structural picture for the different energetic balance of native and folding transition states.
Key Words:
Desolvation barrier, Folding transition state, Protein folding, Protein unfolding, Solvation barrier, Unfolding rates
