title: Evidence of chemical exchange in recombinant Major Urinary Protein and quenching thereof upon pheromone binding.
abstract: The internal dynamics of recombinant Major Urinary Protein (rMUP) have been investigated by monitoring transverse nitrogen-15 relaxation using multiple-echo Carr-Purcell-Meiboom-Gill (CPMG) experiments. While the ligand-free protein (APO-rMUP) features extensive evidence of motions on the milliseconds time scale, the complex with 2-methoxy-3-isobutylpyrazine (HOLO-rMUP) appears to be much less mobile on this time scale. At 308 K, exchange rates k (ex) = 500-2000 s(-1) were typically observed in APO-rMUP for residues located adjacent to a beta-turn comprising residues 83-87. These residues occlude an entry to the binding pocket and have been proposed to be a portal for ligand entry in other members of the lipocalin family, such as the retinol binding protein and the human fatty-acid binding protein. Exchange rates and populations are largely uncorrelated, suggesting local 'breathing' motions rather than a concerted global conformational change.
authors.affiliation: Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne, 1015, Lausanne, Switzerland. Chiara.Perazzolo@epfl.ch
authors.forename: Chiara
authors.initials: C
authors.lastname: Perazzolo
authors.forename: Mariachiara
authors.initials: M
authors.lastname: Verde
authors.forename: Steve W
authors.initials: SW
authors.lastname: Homans
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Bodenhausen
mesh_terms: D000818:Animals; D003198:Computer Simulation; D009587:Nitrogen Isotopes; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods; D011485:Protein Binding; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry* / Q000235:genetics; D011719:Pyrazines / Q000737:chemistry; D011994:Recombinant Proteins / Q000737:chemistry*
chemical_list: D009587:Nitrogen Isotopes; D011506:Proteins; D011719:Pyrazines; D011994:Recombinant Proteins; C035737:major urinary proteins; C034376:2-isobutyl-3-methoxypyrazine