The characterization of interactions between biological macromolecules is an essential step in the structural analysis of complexes of biomolecules, whether for a preliminary characterization of affinity or a thorough analysis of the thermodynamic parameters of a reaction. The protein-protein interactions platform is located across several rooms in the Bellini Life Sciences Complex and comprises three isothermal titration calorimeters (ITC) and an surface plasmon resonance set-up (OpenSPR) for measuring binding affinities, multiangle and dynamic light scattering instruments and analytical ultracentrifuges for characterizing protein molecular mass, a circular dichroism (CD) spectrometer for determining protein secondary structure, a Biocomp Gradient Station for purification, crosslinking and molecular density analysis and several fluorometers for measuring binding affinities and protein stability.