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NMR characterization of a pH‐dependent equilibrium between two folded solution conformations of the pheromone‐binding protein from Bombyx mori
Author(s) -
Damberger Fred,
Horst Reto,
Wüthrich Kurt,
Peng Guihong,
Nikonova Larisa,
Leal Walter Soares
Publication year - 2000
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.9.5.1038
Subject(s) - chemistry , bombyx mori , ligand (biochemistry) , nuclear magnetic resonance spectroscopy , chemical shift , crystallography , conformational change , stereochemistry , biochemistry , receptor , gene
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 welldispersed 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.