Sulfonium-Containing Glycopolypeptides Tethering Trehalose for Protein Stabilization.

Protection of proteins is of great significance since external stimuli can cause denaturation due to aggregation. Herein, a series of well-defined cationic trehalose-glycopolypeptides, poly(ethylene glycol)--(l-methionine--trehalose)s (PEG--(Met--Tre)), were synthesized for stabilization of a model protein, glucose oxidase (GOx), against lyophilization and heating. The isothermal titration calorimetry results revealed that polyionic complexes (PICs) were formed between the synthesized trehalose-glycopolypeptides and GOx via electrostatic interactions. These PICs allowed GOx to maintain an approximately 80% enzymatic activity compared with native GOx after 6× lyophilization. Meanwhile, PEG--(Met--Tre) also provided a positive effect on the protection of GOx upon heating at 60 °C. Results of transmission electron microscopy suggested that the trehalose-glycopolypeptides could prevent protein aggregation, thereby maintaining the bioactive function of GOx. In brief, it provided a synthesis strategy for the precise preparation of trehalose-glycopolypeptides, as well as a suitable method for stabilization of proteins.