title: NMR characterization of a pH-dependent equilibrium between two folded solution conformations of the pheromone-binding protein from Bombyx mori.
abstract: NMR spectroscopic changes as a function of pH in solutions of the pheromone-binding protein of Bombyx mori (BmPBP) show that BmPBP undergoes a conformational transition between pH 4.9 and 6.0. At pH below 4.9 there is a single "acid form" (A), and a homogeneous "basic form" (B) exists at pH above 6.0. Between pH 5 and 6, BmPBP exists as a mixture of A and B in slow exchange on the NMR chemical shift time scale, with the transition midpoint at pH 5.4. The form B has a well-dispersed NMR spectrum, indicating that it represents a more structured, "closed" conformation than form A, which has a significantly narrower chemical shift dispersion. Conformational transitions of the kind observed here may explain heterogeneity reported for a variety of odorant-binding proteins, and it will be of interest to further investigate possible correlations with pH-dependent regulation of ligand binding and release in the biological function of this class of proteins.
authors.affiliation: Institut für Molekularbiologie und Biophysik, Eidgenössische Technische Hochschule Hönggerberg, Zürich, Switzerland.
authors.forename: F
authors.initials: F
authors.lastname: Damberger
authors.forename: L
authors.initials: L
authors.lastname: Nikonova
authors.forename: R
authors.initials: R
authors.lastname: Horst
authors.forename: G
authors.initials: G
authors.lastname: Peng
authors.forename: W S
authors.initials: WS
authors.lastname: Leal
authors.forename: K
authors.initials: K
authors.lastname: Wüthrich
mesh_terms: D000818:Animals; D012831:Bombyx / Q000737:chemistry*; D002352:Carrier Proteins / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D004926:Escherichia coli / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D019476:Insect Proteins / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D011487:Protein Conformation; D020033:Protein Isoforms; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012984:Software
chemical_list: D002352:Carrier Proteins; D019476:Insect Proteins; D020033:Protein Isoforms; D011994:Recombinant Proteins; C403713:pheromone binding protein, insect