Open AccessAmino‐acid‐sequence determination and biological activity of tessulin, a naturally occurring trypsin‐chymotrypsin inhibitor isolated from the leech Theromyzon tessulatum
Author(s) -
Chopin Vincent,
Stefano George B.,
Salzet Michel
Publication year - 1998
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1327.1998.2580662.x
Subject(s) - trypsin , chymotrypsin , cathepsin g , edman degradation , chemistry , biochemistry , serine protease , pancreatic elastase , serine , amino acid , protease , peptide sequence , aprotinin , proteases , peptide , thrombin , elastase , enzyme , biology , medicine , platelet , surgery , immunology , gene
We purified a new trypsin−chymotrypsin inhibitor, designated tessulin, from the rhynchobdellid leech Theromyzon tessulatum . This 9‐kDa peptide was purified to apparent homogeneity by gel‐permeation and anion‐exchange chromatographies followed by reverse‐phase HPLC. The structure of tessulin was determined by reduction, S ‐β‐pyridylethylation, trypsin digestion, automated Edman degradation and matrix‐assisted laser desorption mass spectrometry ( m / z 8985 Da). The 81‐amino‐acid peptide possesses 16 cysteines and exhibits a 16 % sequence similarity with antistasin‐type inhibitors. Tessulin inhibits trypsin ( K i 1 pM) and chymotrypsin ( K i 150 pM) and exhibits no activity with thrombin, factor Xa, cathepsin G and elastase. This is the first trypsin−chymotrypsin inhibitor isolated from leeches that does not inhibit elastase or cathepsin G, except for cytin and therin. Furthermore, tessulin, in conjunction with other serine‐protease inhibitors isolated from Theromyzon (therin, theromin), significantly diminishes the level of human granulocyte and monocyte activation induced by lipopolysaccharides (10 μg). The combined level of inhibition is higher than that of aprotinin, another serine‐protease inhibitor used biomedically. Thus, tessulin may be clinically significant in reducing inflammatory events.