Molecular dynamics studies of odorant binding protein free of ligand and complexed to pyrazine and octenol

The dynamic behaviour analysis of porcine OBP, free of ligand, and complexed with 2-isobutyl-3-methoxypyrazine and 2,6-dimethyl-7-octen-2-ol has been performed by means of molecular dynamics simulations. The simulations reveal that the OBP cavity, while being hydrophobic, is likely to produce hydrophilic interactions with some of the internal residues. A large evolution of the OBP cavity volume has been observed, ranging between 400 and 800 Å3 independently of the ligand buried into the cavity. The hydrophobic cavity is shielded from the solvent, but openings have been observed, triggered by shifts of residues considered to constitute the door of the cavity, especially tyrosine 82.