title: NMR unfolding studies on a liver bile acid binding protein reveal a global two-state unfolding and localized singular behaviors.
abstract: The folding properties of a bile acid binding protein, belonging to a subfamily of the fatty acid binding proteins, have been here investigated both by hydrogen exchange measurements, using the SOFAST NMR approach, and urea denaturation experiments. The urea unfolding profiles of individual residues, acting as single probes, were simultaneously analyzed through a global fit, according to a two-state unfolding model. The resulting conformational stability DeltaG(U)(H(2)O)=7.2+/-0.25kcal mol(-1) is in good agreement with hydrogen exchange stability DeltaG(op). While the majority of protein residues satisfy this model, few amino-acids display a singular behavior, not directly amenable to the presence of a folding intermediate, as reported for other fatty acid binding proteins. These residues are part of a protein patch characterized by enhanced plasticity. To explain this singular behavior a tentative model has been proposed which takes into account the interplay between the dynamic features and the formation of transient aggregates. A functional role for this plasticity, related to translocation across the nuclear membrane, is discussed.
authors.affiliation: Dipartimento Scientifico e Tecnologico, Strada le Grazie 15, Università degli Studi di Verona, Verona, Italy.
authors.forename: Mariapina
authors.initials: M
authors.lastname: D'Onofrio
authors.forename: Laura
authors.initials: L
authors.lastname: Ragona
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Fessas
authors.forename: Marco
authors.initials: M
authors.lastname: Signorelli
authors.forename: Raffaella
authors.initials: R
authors.lastname: Ugolini
authors.forename: Massimo
authors.initials: M
authors.lastname: Pedò
authors.forename: Michael
authors.initials: M
authors.lastname: Assfalg
authors.forename: Henriette
authors.initials: H
authors.lastname: Molinari
mesh_terms: D002352:Carrier Proteins / Q000737:chemistry*; D008562:Membrane Glycoproteins / Q000737:chemistry*; D019906:Nuclear Magnetic Resonance, Biomolecular; D017510:Protein Folding; D011994:Recombinant Proteins / Q000737:chemistry
chemical_list: D002352:Carrier Proteins; D008562:Membrane Glycoproteins; D011994:Recombinant Proteins; C037643:bile acid binding proteins