Glass-like protein condensate for the long-term storage of proteins

Long-term storage of proteins at ambient temperature is required for applications in pharmaceutics and biotechnology. Lyophilization is a versatile approach for stabilizing proteins at ambient temperature, although its freezing and drying processes negatively affect the protein structure. In this study, we show a glass-like protein condensate (GLPC) as a new method for protein stabilization at ambient temperature. Various protein types, including immunoglobulin G, gamma globulin, albumin, and chymotrypsin, formed a glassy state during ultracentrifugation and natural drying, while proteins that tend to crystalize, such as hen egg-white lysozyme, did not. The GLPCs were characterized by a transparent solid state, similar to a dry glass ball. Importantly, the GLPCs were dissolved easily in saline solution at a physiological concentration, thereby retaining their native structures and functions. The GLPCs preserved their native structures even after 1 year of incubation at ambient temperature. These results provide a framework for the development of protein preservation methods at ambient temperature other than lyophilization.