Spectroscopic evaluation of the stabilization of humanized monoclonal antibodies in amino acid formulations.

The protective effects of amino acids on stabilizing protein secondary structure were evaluated using diffuse reflectance FTIR spectroscopy, and interactions between proteins and arginine were detected using solid-state NMR spectroscopy. Upon freeze-drying, excipient-free anti-CD11a and anti-IgE antibodies underwent significant changes in their secondary structures. For both antibodies, the amount of intermolecular beta-sheet substantially increased and the native conformation of intramolecular beta-sheet content decreased considerably.