Sulfonium-Containing Glycopolypeptides Tethering Trehalose for Protein Stabilization

Abstract

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)-b-(l-methionine-g-trehalose)­s (PEG45-b-(Met-g-Tre) x ), 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, PEG45-b-(Met-g-Tre) x 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.

Activation of Upper Critical Solution Temperature Behaviors of Zwitterionic Poly(l-methionine-g-poly(sulfobetaine methacrylate)m) with a Bottlebrush Structure

“…41−43 In our previous work, alkylation of poly(Lmethionine) (PMet) showed high reaction efficiency under mild conditions, allowing for the introduction of functional trehalose groups via the subsequent click reaction. 44 In this study, we chose alkylated PMet as the macroinitiator to prepare a zwitterionic bottlebrush polypeptide, endowing the backbone with structurally biodegradable properties. The polymerization of SBMA monomers (Scheme 1) was performed via the ATRP technique to produce the zwitterionic bottlebrush P(Met50-g-(PSBMA) m ) (MS-m).…”

“…Researchers have chosen synthetic polypeptides as the main chain to avoid potential biocompatibility issues caused by the carbon-based backbone. − Bromo-functionalized poly­( l -lysine) has been used as the ATRP macroinitiator to produce polypeptide bottlebrushes . Subsequently, the polypeptide side chains were chemically modified for subsequent reactions via the postpolymerization modification route. , The alkylation of l -methionine (Met) residues has been expanded to a wide range of functional groups on polypeptides. − In our previous work, alkylation of poly­( l -methionine) (PMet) showed high reaction efficiency under mild conditions, allowing for the introduction of functional trehalose groups via the subsequent click reaction …”