Engineered Protein Copolymers for Heparin Neutralization and Detection

Abstract

Heparin is a widely applied anticoagulant agent. However, in clinical practice, it is of vital importance to reverse its anticoagulant effect to restore the blood-clotting cascade and circumvent side effects. Inspired by protein cages that can encapsulate and protect their cargo from surroundings, we utilize three designed protein copolymers to sequester heparin into inert nanoparticles. In our design, a silk-like sequence provides cooperativity between proteins, generating a multivalency effect that enhances the heparin-binding ability. Protein copolymers complex heparin into well-defined nanoparticles with diameters below 200 nm. We also develop a competitive fluorescent switchon assay for heparin detection, with a detection limit of 0.01 IU mL −1 in plasma that is significantly below the therapeutic range (0.2−8 IU mL −1 ). Moreover, moderate cytocompatibility is demonstrated by in vitro cell studies. Therefore, such engineered protein copolymers present a promising alternative for neutralizing and sensing heparin, but further optimization is required for in vivo applications.

Caltrop-like Small-Molecule Antidotes That Neutralize Unfractionated Heparin and Low-Molecular-Weight Heparin In Vivo

“…In the past decade, a number of heparin antidotes have been developed, which include cationic macromolecules or polymers, − supramolecular polymers or frameworks, − peptides and proteins, − and various small molecules, including aminoquincarbamide surfen, sulfonated calix­[ n ]­arene, aromatic amide-derived foldamers, piperazine-derived arginine dimer PER977, spermine-derived library of amines, and γ-cyclodextrin-derived octacarboxylate . Compared with macromolecular and polymeric counterparts, small-molecule antidotes have single structures, which endow them with several advantages such as more controllable synthesis and quality, more predictable efficacy, higher storage stability, and easier analysis of distribution and metabolism in body.…”

Recombinant supercharged polypeptides for safe and efficient heparin neutralization

“…Various alternatives for PS have been proposed over the last decades, which include, to name a few, polymeric compounds, [9][10][11][12][13][14][15][16] cationic oligopeptides, [17][18][19][20][21] recombinant systems, [22][23][24] and supramolecular assemblies. [25][26][27] However, problems related to the existing systems should not be overlooked.…”