title: Effects of protein-pheromone complexation on correlated chemical shift modulations.
abstract: Major urinary protein (MUP) is a pheromone-carrying protein of the lipocalin family. Previous studies by isothermal titration calorimetry (ITC) show that the affinity of MUP for the pheromone 2-methoxy-3-isobutylpyrazine (IBMP) is mainly driven by enthalpy, with a small unfavourable entropic contribution. Entropic terms can be attributed in part to changes in internal motions of the protein upon binding. Slow internal motions can lead to correlated or anti-correlated modulations of the isotropic chemical shifts of carbonyl C' and amide N nuclei. Correlated chemical shift modulations (CSM/CSM) in MUP have been determined by measuring differences of the transverse relaxation rates of zero- and double-quantum coherences ZQC{C'N} and DQC{C'N}, and by accounting for the effects of correlated fluctuations of dipole-dipole couplings (DD/DD) and chemical shift anisotropies (CSA/CSA). The latter can be predicted from tensor parameters of C' and N nuclei that have been determined in earlier work. The effects of complexation on slow time-scale protein dynamics can be determined by comparing the temperature dependence of the relaxation rates of APO-MUP (i.e., without ligand) and HOLO-MUP (i.e., with IBMP as a ligand).
authors.affiliation: Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne, BCH, 1015, Lausanne, Switzerland.
authors.forename: Chiara
authors.initials: C
authors.lastname: Perazzolo
authors.forename: Julien
authors.initials: J
authors.lastname: Wist
authors.forename: Karine
authors.initials: K
authors.lastname: Loth
authors.forename: Luisa
authors.initials: L
authors.lastname: Poggi
authors.forename: Steve
authors.initials: S
authors.lastname: Homans
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Bodenhausen
mesh_terms: D000596:Amino Acids; D018360:Crystallography, X-Ray; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D010675:Pheromones / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry*; D013696:Temperature
chemical_list: D000596:Amino Acids; D008024:Ligands; D010675:Pheromones; D011506:Proteins; C035737:major urinary proteins