title: Equilibrium folding studies of cellular retinoic acid binding protein, a predominantly beta-sheet protein.
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.
authors.affiliation: Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas 75235-9041.
authors.forename: Z P
authors.initials: ZP
authors.lastname: Liu
authors.forename: J
authors.initials: J
authors.lastname: Rizo
authors.forename: L M
authors.initials: LM
authors.lastname: Gierasch
mesh_terms: D002942:Circular Dichroism; D004591:Electrophoresis, Polyacrylamide Gel; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D011487:Protein Conformation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D018168:Receptors, Retinoic Acid / Q000737:chemistry* / Q000302:isolation & purification; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification; D012996:Solutions; D014270:Trifluoroethanol; D014508:Urea
chemical_list: D018168:Receptors, Retinoic Acid; D011994:Recombinant Proteins; D012996:Solutions; D014270:Trifluoroethanol; D014508:Urea