Equilibrium folding studies of cellular retinoic acid binding protein, a predominantly .beta.-sheet protein
- 11 January 1994
- journal article
- research article
- Published by American Chemical Society (ACS) in Biochemistry
- Vol. 33 (1) , 134-142
- https://doi.org/10.1021/bi00167a017
Abstract
We have examined the conformational behavior under various unfolding conditions of a predominantly beta-sheet protein, cellular retinoic acid binding protein (CRABP). Urea unfolding-refolding of CRABP is a highly cooperative process that can be approximated by a two-state model. Acid denaturation is also cooperative and reversible and leads to a state containing nonnative residual structure: Below pH 2.6, CRABP contains a substantially larger amount of alpha-helix than under native conditions. CRABP adopts up to 75% alpha-helix in solutions containing a high percentage of 2,2,2-trifluoroethanol. The acid-denatured state of CRABP undergoes a conformational change to a state containing predominantly beta-sheet structure upon the addition of small amounts of Na2SO4. This conformational malleability may be important for the folding mechanism of CRABP. The possible implication of nonnative alpha-helical structure in the folding of CRABP is discussed.Keywords
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