American Society of Hirudotherapy

A cysteine-rich serine protease inhibitor (Guamerin II) from the non-blood sucking leech Whitmania edentula

Biochemistry study published in Journal of Enzyme Inhibition (1996)

Last Updated: June 18, 2026Reviewed by: ASH Editorial Board
Research article — evidence reviewArticle reference
Evidence: Research reportSalivary PharmacologyKim DR et al. · Journal of enzyme inhibition, 1996

Abstract

A cysteine-rich serine protease inhibitor (Guamerin II) was isolated from the non-blood sucking leech Whitmania edentula. The new inhibitor was identified as a low molecular weight (6,012 Da) polypeptide with some sequence similarities to antistasin, hirustasin and guamerin. The inhibitor contained 56 amino acid residues with 76.8% sequence similarity to guamerin, 48.2% to hirustasin and 28.6% to the first domain of antistasin. This new inhibitor was the first completely sequenced serine protease inhibitor from a non-blood sucking leech. Analysis of the inhibitor revealed that it was active against neutrophil elastase and chymotrypsin, but had no activity against a variety of other proteases. The P1 reactive site residue was identified as methionine and the residues surrounding the P1 site were hydrophobic amino acids. The primary structure of the inhibitor showed no similarity to well-known elastase inhibitors from leeches such as eglin.

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 AcidsAnimalsChromatography, GelChromatography, High Pressure LiquidChromatography, Ion ExchangeChymotrypsinCysteineHumansInvertebrate HormonesLeechesLeukocyte Elastase

Summary

Isolation, sequencing and characterization of Guamerin II, a cysteine-rich serine protease inhibitor from non-blood-sucking leech Whitmania edentula — novel scaffold.

Why This Matters for Hirudotherapy

This study isolated and characterized Guamerin II, a cysteine-rich serine protease inhibitor of 6,012 Da (56 amino acid residues), from the non-blood-sucking leech Whitmania edentula—the first completely sequenced serine protease inhibitor from a non-blood-sucking leech. Guamerin II showed 76.8% sequence similarity to guamerin, 48.2% to hirustasin, and 28.6% to the first domain of antistasin; it was active against neutrophil elastase and chymotrypsin but not other tested proteases, with a methionine P1 reactive site. This is relevant to ASH's domain as it expands knowledge of the leech secretome and bioactive protease inhibitors, even from a non-hematophagous species. Caveat: the study is purely biochemical with no clinical or in vivo therapeutic data, and Guamerin II has no demonstrated anticoagulant or hirudin-like activity.

Citation

A cysteine-rich serine protease inhibitor (Guamerin II) from the non-blood sucking leech Whitmania edentula.

Kim DR et al. · Journal of enzyme inhibition, 1996

DOI

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

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