Aggregation properties of proteins under high pressure

Fourier transform infrared spectroscopy (FTIR) coupled with High Pressure (HP) techniques is a suitable tool to investigate unfolding/misfolding processes providing useful information on the kinetics of aggregation of proteins[1]. Since HP affects only the volume contribution to the Gibbs free energy, it is able to perturb the structure of proteins in a reversible way [2][3]. The principle governing pressure effects is that it tends to shift a system towards the state that occupies the smallest volume, it causes the electrostriction of charged and polar groups, the elimination of packing defects, and the solvation of hydrophobic groups. Cavities and packing defects are expected to be major contributors to volume changes and their presence will make the system more susceptible to pressure unfolding/dissociation. Because high pressure allows stabilization of folding intermediates such as molten-globule conformations, this method provides an unique opportunity for their characterization. We present here latest developments in the set up of a high pressure infrared facility for the study of protein folding misfolding and aggregations at the SISSI beamline at Elettra.