American Society of Hirudotherapy

Two engineered eglin c mutants potently and selectively inhibiting kexin or furin

Basic science published in FEBS Lett (2004)

Last Updated: June 18, 2026Reviewed by: ASH Editorial Board
Research article — evidence reviewArticle reference
Evidence: Research reportDrug DevelopmentGenomics & ProteomicsLiu Z et al. · FEBS letters, 2004

Abstract

Eglin c with mutants L45R and D42R at the P(1) and P(4) positions has been reported to become a stable inhibitor toward the proprotein convertases (PC), furin and kexin, with a K(i) of 2.3x10(-8) and 1.3x10(-10) M, respectively. The mutant was further engineered at the P(2)'-P(4)' positions to create a more potent and selective inhibitor for each enzyme. The residue Asp at P(1)' which is crucial for stabilizing the conformation of eglin c remained unchanged. The eglin c mutants cloned into the vector pGEX-2T and expressed in Escherichia coli (DH5alpha) were purified to homogeneity, and their inhibitory activities toward the purified recombinant furin and kexin were examined. The results showed that (1) Leu47 at P(2)' replaced with either a positively or negatively charged residue resulted in a decrease in inhibitory activities to both enzymes; (2) the replacement of Arg with Asp at P(3)' was favorable for inhibiting furin with a K(i) of 7.8 x 10(-9) M, but not for inhibiting kexin; (3) the replacement of Tyr with Glu at P(4)' increased the inhibitory activity to kexin with a K(i) of 3 x 10(-11) M, but was almost without any influence on furin inhibition. It was indicated that the inhibitory specificity of eglin c could be changed from inhibiting elastase to inhibiting PCs by site-directed mutation at the P positions, while the inhibitory selectivity to furin or kexin could be optimized by mutation at the P' positions.

Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.

Publication typeJournal ArticleResearch Support, Non-U.S. Gov't
Indexed MeSH termsAmino Acid SequenceAmino Acid SubstitutionEnzyme InhibitorsEscherichia coliFurinKineticsMutagenesis, Site-DirectedProprotein ConvertasesProteinsRecombinant Fusion ProteinsSaccharomyces cerevisiae ProteinsSerpins

Summary

Site-directed mutagenesis of eglin C yields potent furin (Ki 7.8x10^-9 M) and kexin (Ki 3x10^-11 M) inhibitors.

Why This Matters for Hirudotherapy

This study engineered eglin c mutants through site-directed mutagenesis at P(2)'–P(4)' positions to create potent and selective inhibitors of the proprotein convertases furin and kexin. The abstract details how specific amino acid substitutions modulated inhibitory activity, achieving Ki values as low as 3 × 10⁻¹¹ M for kexin and 7.8 × 10⁻⁹ M for furin. The work demonstrates that eglin c's specificity can be shifted from elastase to proprotein convertases through targeted mutations. The abstract does not mention leeches, leech-derived proteins, hirudotherapy, or any connection to leech biology. The study was conducted entirely in vitro using recombinant proteins expressed in *Escherichia coli*. Based on the abstract alone, this research has no defensible or direct relevance to hirudotherapy or ASH's domain.

Citation

Two engineered eglin c mutants potently and selectively inhibiting kexin or furin.

Liu Z et al. · FEBS letters, 2004

DOI

Added to ASH library: May 27, 2026 · Site last updated: June 18, 2026

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