Screening for physical stability of a Pseudomonas amylase using self-interaction chromatography

Formulation development is an integral step in the successful commercialization of protein-based products in both the biotechnology and pharmaceutical industries. As the number of these protein formulations increases, so does the need for innovative approaches to characterize physical and chemical product stability. In this study, the osmotic second virial coefficient (B) of a commercial amylase was evaluated by self-interaction chromatography (SIC) as an innovative approach to characterize physical protein stability. B was measured as a function of pH and several common formulation additives (cosolvents), including sodium chloride, sucrose, and sorbitol. Cosolvent- and pH-induced physical stabilization of amylase is discussed in terms of positive shifts in B. Liquid chromatographic measurements of total soluble amylase and enzymatic activity measurements correlated qualitatively with trends in B except near the pI of amylase, where physical stability was minimal.