How to Characterize the Protein Structure and Polymer Conformation in Protein-Polymer Conjugates - a Perspective

Proteins, having miscellaneous properties perfected by nature over millions of years, are attractive for many biomedical and industrial applications. The exploitation of proteins offers great opportunities to increase, among others, the selectivity, biocompatibility, and sustainability of artificial materials. However, the stability of proteins is limited and exposure to conditions like heat or organic solvents often leads to denaturation or aggregation. The modification with synthetic polymers is a powerful possibility to increase the stability of proteins. Throughout the last few years, various methods have been established to characterize obtained conjugates regarding the conjugation efficiency, protein stability, their self-assembly behavior, and beyond. Nevertheless, it is still very challenging to determine if the protein structure is unaltered in the biohybrid materials and how the polymer chains arrange around the protein surface. Here, an overview of different analysis techniques is presented, their applicability and feasibility are discussed, and current literature examples are provided. The focus of this Perspective lies on nuclear magnetic resonance spectroscopy, size exclusion chromatography coupled with multi-angle laser light scattering, analytical ultracentrifugation, and small-angle scattering techniques as these methods shed light into the structure of proteins in conjugates and the polymer conformation around proteins.

Automated summary

Proteins, with their diverse properties developed over millions of years, have great potential for applications in biomedicine and industry. However, their stability is limited and exposure to certain conditions can cause denaturation or aggregation. Modification with synthetic polymers is a powerful approach to enhance protein stability. Various methods have been established to characterize protein-polymer conjugates, but determining the structural integrity of proteins in biohybrid materials and the arrangement of polymer chains around proteins remains challenging. This Perspective provides an overview of different analysis techniques, discusses their applicability and feasibility, and presents current literature examples. The focus is on techniques such as nuclear magnetic resonance spectroscopy, size exclusion chromatography coupled with multi-angle laser light scattering, analytical ultracentrifugation, and small-angle scattering, which provide insights into protein structure and polymer conformation.