Abstract: The sedimentation velocity analytical ultracentrifugation （AUC-SV） is a classical biophysical technique for determining the size and shape of molecules in solution, enabling characterization of molecular interactions with regard to the number, size, stoichiometry, and affinity of complexes formed in association processes. A method for the analysis of receptor and ligand interactions between CD32b, an important immune marker molecule, and Fc fragment of Human IgG1 antibody, was established by AUC-SV. Parallel experiments were conducted alongside classical methods for protein-protein interaction （PPI） analysis, such as surface plasmon resonance （SPR） and micro-scale thermophoresis （MST）. The reliability of the SV-AUC methodology for the analysis of PPI was further validated.

Key words: AUC-SV, PPI, CD32b, Fc