Temperature dependence on structure and dynamics of Bovine Pancreatic Trypsin Inhibitor (BPTI): A neutron scattering study

We have studied the influence of temperature on the structure of BPTI in solution by small angle neutron scattering. We have investigated the variation of the radius of gyration and the modification of the shape of BPTI between ambient temperature and 368 K. Results have shown an increase of the radius of gyration from 10.9 Å at ambient temperature up to 13.3 Å at 368 K. Global and internal dynamics of BPTI in solution were studied by quasielastic neutron scattering. The analysis of neutron data in terms of intermediate scattering function reveals two relaxation times τ1 and τ2 related respectively to global translational diffusive motions and to internal motions of protein. Motions of protons belonging to lateral chains of residues located at the surface of the protein have been detected. The results are compared to the recently published results concerning the influence of pressure on structure and dynamics of BPTI in solution [Appavou MS et al. Biochimica et Biophysica Acta, 1764, 2006, pp 414–423].