Design of Stomach Acid-Stable and Mucin-Binding Enzyme Polymer Conjugates

The reduced immunogenicity and increased stability of protein–polymer conjugates has made their use in therapeutic applications particularly attractive. However, the physicochemical interactions between polymer and protein, as well as the effect of this interaction on protein activity and stability, are still not fully understood. In this work, polymer-based protein engineering was used to examine the role of polymer physicochemical properties on the activity and stability of the chymotrypsin–polymer conjugates and their degree of binding to intestinal mucin. Four different chymotrypsin–polymer conjugates, each with the same polymer density, were synthesized using “grafting-from” atom transfer radical polymerization. The influence of polymer charge on chymotrypsin–polymer conjugate mucin binding, bioactivity, and stability in stomach acid was determined. Cationic polymers covalently attached to chymotrypsin showed high mucin binding, while zwitterionic, uncharged, and anionic polymers showed no mucin bind...