A novel locust (Schistocerca gregaria) serine protease inhibitor with a high affinity for neutrophil elastase

Abstract

We have purified to homogeneity two forms of a new serine protease inhibitor specific for elastase/chymotrypsin from the ovary gland of the desert locust Schistocerca gregaria. This protein, greglin, has 83 amino acid residues and bears putative phosphorylation sites. Amino acid sequence alignments revealed no homology with pacifastin insect inhibitors and only a distant relationship with Kazal-type inhibitors. This was confirmed by computer-based structural studies. The most closely related homologue is a putative gene product from Ciona intestinalis with which it shares 38% sequence homology. Greglin is a fast-acting and tight binding inhibitor of human neutrophil elastase (k(ass)=1.2x10(7) M(-1) x s(-1), K(i)=3.6 nM) and subtilisin. It also binds neutrophil cathepsin G, pancreatic elastase and chymotrypsin with a lower affinity (26 nM< or =K(i)< or =153 nM), but does not inhibit neutrophil protease 3 or pancreatic trypsin. The capacity of greglin to inhibit neutrophil elastase was not significantly affected by exposure to acetonitrile, high temperature (90 degrees C), low or high pH (2.5-11.0), N-chlorosuccinimide-mediated oxidation or the proteolytic enzymes trypsin, papain and pseudolysin from Pseudomonas aeruginosa. Greglin efficiently inhibits the neutrophil elastase activity of sputum supernatants from cystic fibrosis patients. Its biological function in the locust ovary gland is currently unknown, but its physicochemical properties suggest that it can be used as a template to design a new generation of highly resistant elastase inhibitors for treating inflammatory diseases.

Juvenile hormone–dependent Kazal‐type serine protease inhibitor Greglin safeguards insect vitellogenesis and egg production

“…Greglin, initially named for an antielastase protein isolated from S. gregaria ovaries (47), represents a novel member of nonclassic Kazal-type serine protease inhibitors targeting elastase and chymotrypsin. Previously, the function of Greglin has only been reported in S. gregaria, and its inhibitory activities have solely been determined by structural and biochemical analyses of purified Greglin protein (47,48). In the present study, we demonstrated that Greglin appeared to be specifically expressed in adult female locusts and was the third of the 3 most highly expressed genes, after 2 Vg genes.…”

SdPI, The First Functionally Characterized Kunitz-Type Trypsin Inhibitor from Scorpion Venom

“…Then the samples were added to preheated test tubes and incubated for 1 hour at temperatures from 25°C to 100°C [35]. The residual trypsin inhibitory activity of rSdPI peptide was determined by the method described above.…”

Targeting neutrophil elastase in cystic fibrosis

“…More recently work has been done on greglin, a novel locust serine protease inhibitor with a high affinity for NE [100]. This is a fast acting and tight binding inhibitor of human NE, which also binds neutrophil cathepsin G, pancreatic elastase and chymotrypsin with lower affinity.…”