Influence of low-molecular-weight aggregates on aggregate growth kinetics and physical properties of solid-state proteins during storage

[Display omitted] Low-molecular-weight (LMW) aggregate is a critical determinant of subsequent protein aggregation, but the aggregate growth kinetics of solid proteins have not been fully characterized. In this study, the high-molecular weight (HMW) aggregate formation process for solid-state proteins and the relationship between aggregation and physical properties of tablets were evaluated using proteins with various initial aggregate ratios. Quantitative changes in monomers, LMW aggregates, and HMW aggregates during storage were measured. The monomer amount decreased uniformly for all proteins. Proteins with low initial LMW aggregates showed remarkable increases in LMW aggregates but little increases in HMW aggregates during storage. Proteins with high initial LMW aggregates showed decreases in LMW aggregates but remarkable increases in HMW aggregates. A correlation analysis and logistic regression indicated that HMW aggregate formation depended on the initial quantity of LMW aggregates. Furthermore, the initial LMW aggregate ratio was related to the disintegratability of protein-containing tablets after storage. These results provide novel insight into solid-state protein aggregation and may guide the prediction of the long-term quality of solid protein-containing pharmaceuticals and foods without storage.