title: Residual interactions in unfolded bile acid-binding protein by 19F NMR.
abstract: The folding initiation mechanism of human bile acid-binding protein (BABP) has been examined by (19) F NMR. Equilibrium unfolding studies of BABP labeled with fluorine at all eight of its phenylalanine residues showed that at least two sites experience changes in solvent exposure at high denaturant concentrations. Peak assignments were made by site-specific 4FPhe incorporation. The resonances for proteins specifically labeled at Phe17, Phe47, and Phe63 showed changes in chemical shift at denaturant concentrations at which the remaining five phenylalanine residues appear to be fully solvent-exposed. Phe17 is a helical residue that was not expected to participate in a folding initiation site. Phe47 and Phe63 form part of a hydrophobic core region that may be conserved as a site for folding initiation in the intracellular lipid-binding protein family.
authors.affiliation: Department of Biochemistry and Molecular Biology, Penn State University College of Medicine, Hershey, Pennsylvania 17022, USA.
authors.forename: H Kenney
authors.initials: HK
authors.lastname: Basehore
authors.forename: Ira J
authors.initials: IJ
authors.lastname: Ropson
mesh_terms: D005461:Fluorine / Q000737:chemistry; D006801:Humans; D006913:Hydroxysteroid Dehydrogenases / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods; D010649:Phenylalanine / Q000737:chemistry / Q000378:metabolism; D017510:Protein Folding; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D014508:Urea / Q000737:chemistry / Q000378:metabolism; D045002:3-alpha-Hydroxysteroid Dehydrogenase (B-Specific)
chemical_list: D005461:Fluorine; D006913:Hydroxysteroid Dehydrogenases; D010649:Phenylalanine; D011994:Recombinant Proteins; D014508:Urea; C435496:AKR1C2 protein, human; D045002:3-alpha-Hydroxysteroid Dehydrogenase (B-Specific)