Shmidov, Y. | bioRxiv Science

bioRxiv2025

Intrinsically Disordered Protein Coating for Oral Delivery of Peptide Drugs

AbstractAdvancing oral delivery of peptide therapeutics requires innovative materials that overcome gastrointestinal barriers. We introduce the first engineered synthetic intrinsically disordered protein (SynIDP) that self-assembles into an enteric coating, encapsulating peptide drugs to enhance gastric acid resistance and intestinal targeting. This SynIDP recapitulates the molecular design principles and phase transitions of native IDPs to exhibit temperature-controlled condensation and pH-controlled solidification--both transitions being reversible and precisely tuned to intestinal cues. Through detailed analysis of the kinetics of the liquid-to-solid phase transition, we achieve control over the nano-to-microscale morphology of the protein coating, optimizing drug encapsulation and protection. The coating protects peptide-based weight loss drugs for over 60 minutes in simulated gastric conditions, then dissolves to release the active compound. Oral delivery to obese mice results in more consistent weight loss compared to the unencapsulated drug. This modular protein-based coating is a promising platform technology for enhancing oral peptide drug delivery and improving patient compliance.

bioengineering↗

bioRxiv2021

Avidity observed between a bivalent inhibitor and an enzyme monomer with a single active site

Although myriad protein-protein interactions in nature use polyvalent binding, in which multiple ligands on one entity bind to multiple receptors on another, to date an affinity advantage of polyvalent binding has been demonstrated experimentally only in cases where the target receptor molecules are clustered prior to complex formation. Here, we demonstrate cooperativity in binding affinity (i.e., avidity) for a protein complex in which an engineered dimer of the amyloid precursor protein inhibitor (APPI), possessing two fully functional inhibitory loops, interacts with mesotrypsin, a soluble monomeric protein that does not self-associate or cluster spontaneously. We found that each inhibitory loop of the purified APPI homodimer was over three-fold more potent than the corresponding loop in the monovalent APPI inhibitor. This observation is consistent with a suggested mechanism whereby the two APPI loops in the homodimer simultaneously and reversibly bind two corresponding mesotrypsin monomers to mediate mesotrypsin dimerization. We propose a simple model for such dimerization that quantitatively explains the observed cooperativity in binding affinity. Binding cooperativity in this system reveals that the valency of ligands may affect avidity in protein-protein interactions including those of targets that are not surface-anchored and do not self-associate spontaneously. In this scenario, avidity may be explained by the enhanced concentration of ligand binding sites in proximity to the monomeric target, which may favor rebinding of the multiple ligand binding sites with the receptor molecules upon dissociation of the protein complex. Impact statementLacham-Hartman et al. demonstrate enhancement of binding affinity through avidity in a complex between a bivalent ligand and a soluble monomeric target with a single binding site. Avidity effects have previously been demonstrated only for clustered receptor molecules presenting multiple binding sites. Our model may explain how polyvalent ligands can agonize or antagonize biological interactions involving nonclustered target molecules that are crucial for intra- and extracellular structural, metabolic, signaling, and regulatory pathways.

biochemistry↗