# Regulating Enzyme Activity via Microaggregates Mediated by Phase Separation

## TL;DR

A new D-peptide strategy uses phase separation to trap harmful enzymes, reducing complications after pancreatic surgery.

## Contribution

A novel D-peptide-mediated microaggregate strategy for enzyme regulation via LSPS is introduced for treating POPF.

## Key findings

- DPMD microaggregates effectively sequester trypsin and chymotrypsin, reducing pancreatic fluid leakage and inflammation.
- DPMD outperformed conventional L-peptide controls in rat models of POPF.
- DPMD was well tolerated at high doses, indicating a favorable safety profile.

## Abstract

Liquid–solid phase separation (LSPS) is a biomolecular segregation process forming solid‐like aggregates that encapsulate and concentrate specific biomolecules, thus profoundly influencing biochemical reactions. Building on this phenomenon, we developed an enzyme‐regulation strategy inducing LSPS of target enzymes to isolate them from substrates. As proof of concept, we created a novel D‐Peptide mediated Microaggregate Degradation named DPMD to capture trypsin and chymotrypsin in the seroperitoneum during postoperative pancreatic fistula (POPF). DPMD is designed with cationic and hydrophobic residues and a β‐sheet‐forming motif for specific binding. The core principle is an entropy‐driven peptide self‐assembly that sequesters these proteases from the extracellular environment. Captured enzymes form intricate peptide–enzyme microaggregates, effectively segregating them from substrates. These microaggregates are readily internalized and cleared by macrophages, likely via macropinocytosis. In rat POPF models, DPMD significantly reduced pancreatic fluid leakage and inflammatory markers, improved survival, and outperformed a conventional L‐peptide control. Toxicity evaluations showed DPMD was well tolerated even at doses beyond therapeutic levels, underscoring its favorable safety profile. In summary, this study demonstrates a significant translational advance in POPF treatment and expands our understanding of pathogenic enzyme sequestration via LSPS, potentially opening new therapeutic avenues for a range of enzyme‐mediated diseases.

An enzyme‐sequestration strategy for combating postoperative pancreatic fistula (POPF) is developed, employing a D‐peptide called DPMD to induce liquid–solid phase separation (LSPS) of pancreatic proteases. This LSPS‐driven microaggregate approach effectively isolates trypsin and chymotrypsin from their substrates, thereby reducing pancreatic fluid leakage and inflammation, and improving survival in a rat POPF model.