Comparative Study of Protein Aggregation Arrest by Zwitterionic Polysulfobetaines: Using Contrasting Raft Agents.

Neha Sharma,Sparsh Makhaik,Kazuaki Matsumura,Robin Rajan

doi:10.1021/acsomega.9b01409

Neha Sharma, Sparsh Makhaik + Show 2 more

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https://doi.org/10.1021/acsomega.9b01409

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Abstract

Protein aggregation has caused limitations in the study and development of protein-based biopharmaceuticals. We prepared different polysulfobetaine (poly-SPB) polymers via reversible addition fragmentation chain transfer (RAFT) polymerization. These polymers exhibited high efficiency in modulation of protein aggregation. We synthesized polysulfobetaines using two different RAFT agents, and analyzed the aggregation profile of lysozyme and insulin. In poly-SPBs, existence of a hydrophobic RAFT agent resulted in visible enhancement of the residual enzymatic activity of lysozyme, whereas it remained unaffected by the hydrophilic RAFT agent. In addition, these polymers resulted in significant suppression in the aggregation of insulin. Increase in the molecular weight of the polymer caused higher efficiency to perpetuate enzymatic activity of lysozyme upon thermal denaturation. The polymers arrested the formation of amyloid like fibrils of lysozyme and insulin, thus indicating their potential to inhibit aggregation. The results unambiguously demonstrate the importance of polysulfobetaine moiety and hydrophobicity in protein aggregation inhibition. This study gives insight into the protein aggregation inhibition by zwitterionic polymers, which have a potential to be developed as aggregation inhibitors in the future.

Highlights

Polysulfobetaines are zwitterionic polymers that have a cationic quaternary ammonium ion and an anionic sulfonate ion on the same monomer unit
Owing to the use of reversible addition fragmentation chain transfer (RAFT) polymerization, the polydispersity index (PDI) was determined to be between 1.1 and 1.5, and the average molecular weights were similar to the theoretical values
Use of higher-molecular-weight polymers, i.e., R1-200 and R2-200, showed that R2-200 exhibits better inhibition than R1-200 (Figure 5c,d). These findings indicate that the hydrophobic RAFT agent (R1) with smaller degrees of polymerization (DP) (20) contributes significantly to arrest the aggregation of insulin (Figure 5e)

Summary

Introduction

Polysulfobetaines (poly-SPBs) are zwitterionic polymers that have a cationic quaternary ammonium ion and an anionic sulfonate ion on the same monomer unit. Polysulfobetaines have been used in industrial applications, as they form open coiled chain structures in solution. The biocompatible properties of polysulfobetaines have been studied recently whose resemblance to phospholipids is responsible for such a behavior.[1−6] Sulfobetaine polymers show good hemocompatibility,[7] have antifouling properties,[8] suppress nonspecific binding of proteins and do not modify the structure of the hydrogenbonded network of water molecules at the interface of the polymer and material.[9,10] They have been used for various applications including wound dressing[8] and cryopreservation,[11] as well as in separation science[12] and drug delivery.[13,14]. Certain amphiphilic proteins[23] and sulfobetaines with nondetergent properties[24] have shown protein aggregation inhibitor properties in solution by assisting in protein folding

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