Rational Control of Protein-Protein Interactions with Protein-ATRP-Generated Protease-Sensitive Polymer Cages

Area of Science:

• Biomaterials Science
• Biochemistry
• Polymer Chemistry

Background:

• Protease-protease interactions are crucial for biological cascades like blood clotting and apoptosis.
• Biomimetic strategies utilize proproteins activated by proteolytic cleavage for targeted drug delivery.
• Previous work showed comb-shaped polymer nanoarmor can shield enzymes and inhibit protein-protein interactions.

Purpose of the Study:

• To synthesize and characterize protease-sensitive comb-shaped nanoarmor cages.
• To create proprotease conjugates that prevent protein-protein interactions until activated by native proteases.
• To investigate the potential of these conjugates in responsive targeted therapies.

Main Methods:

• Atom transfer radical polymerization (ATRP) was used to copolymerize macromonomers and carboxybetaine methacrylate.
• Initiator-labeled chymotrypsin and trypsin enzymes were modified with the polymer.
• Protease-induced cleavage of peptide linkers released PEG side chains from the polymer backbone.

Main Results:

• The synthesized nanoarmor cages were protease-sensitive.
• Proprotease conjugates retained activity against small substrates but not proteins.
• Native proteases triggered release of PEG side chains within 20 minutes, increasing activity against protein substrates by 100%.

Conclusions:

• Protease-sensitive polymer nanoarmor cages can be synthesized using PEG methacrylate macromonomers and peptide linkers.
• These nanoarmored proprotease conjugates offer controlled release of active enzymes.
• Biomimetic cascade initiation with these conjugates may enable novel responsive targeted therapies.