Surface-driven denaturation of proteins during freeze-drying: An insight into the role of surfactants

Protein-based therapeutics may bind to interfaces during the freeze-drying process, possibly resulting in loss of activity. Here we investigate the mechanism by which surfactant molecules can counteract surface-induced denaturation through a detailed study of the stability of the GB1 peptide at the air-water, ice-water and silica-water interfaces. Using molecular dynamics simulations coupled with metadynamics we show that the amphiphilic nature of surfactants is key to their stabilizing/destabilizing effect, with an orientation-dependent mechanism in which the protein is stabilized when the hydrophilic heads of the surfactant point toward the protein.