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WW: An isolated three‐stranded antiparallel β‐sheet domain that unfolds and refolds reversibly; evidence for a structured hydrophobic cluster in urea and GdnHCl and a disordered thermal unfolded state
Author(s) -
Koepf Edward K.,
Petrassi H. Michael,
Sudol Marius,
Kelly Jeffery W.
Publication year - 1999
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.8.4.841
Subject(s) - chaotropic agent , antiparallel (mathematics) , chemistry , crystallography , protein folding , denaturation (fissile materials) , beta sheet , folding (dsp implementation) , native state , biophysics , protein structure , biochemistry , biology , physics , quantum mechanics , magnetic field , electrical engineering , nuclear chemistry , engineering
The objective of this study was to evaluate the suitability of the WW domain as a desirable model system to understand the folding and stability of an isolated three‐stranded antiparallel β‐sheet structure. The WW domain was subjected to thermal and chaotropic denaturation/reconstitution utilizing a variety of biophysical methods. This three‐stranded sheet folds reversibly and cooperatively utilizing both urea and GdnHCl as denaturants; however, the denatured state retains structure in the form of a hydrophobic cluster involving at least one aromatic side chain. In contrast to chaotropic denaturation, thermal denaturation appears to be more complete and may be a two state process. The suitability of the WW domain for future studies aimed at understanding the kinetics and thermodynamics of antiparallel β‐sheet folding clearly emerges from this initial study. The most exciting and significant result in this manuscript is the finding that the chaotropic denatured state of WW has a hydrophobic cluster as discerned by near‐UV CD evidence. The role that the denatured state plays in the folding and stability of a three‐stranded β‐sheets, and its capacity for preventing aggregation may be particularly important and is the subject of ongoing studies.