Glycosylation as a novel stabilization approach preventing aggregation and inactivation of a‐chymotrypsin in the solid‐state and upon encapsulation in bioerodible nanosheperes

Abstract

The complex physicochemical nature of proteins that enhances their potential as pharmaceuticals, also adds to their fragility. Typically, proteins are relatively stable in the solid‐state; however, exposure of lyophilized proteins to excess moisture has been reported to cause undesirable physical and chemical changes. These effects will have a direct impact on solid therapeutic protein formulations and on sustained‐release devises. Therefore, it is important to examine the stability of solid proteins under pharmaceutical relevant conditions. The goal of our study was to examine the stability and structural changes that a protein undergoes after moisture sorption, develop a rational stabilization strategy and prove this in a sustain release. The protein α‐chymotrypsin was used to study the effect of water sorption after incubation at different relative humidities. FTIR, circular dichroism, H/D exchange, enzyme kinetics and aggregation studies were perform. These studies demonstrated that moisture causes deleterious processes to occur to the solid‐state protein. Chemical modification with glycans was performed to test if glycosylation could decrease protein unfolding and aggregation. Results showed that chemical glycosylation reduced and/or prevent these deleterious processes. These glyco‐conjugates are been used to develop sustained release devices; initial results show high encapsulation efficiency and an increase in protein stability.