Elastase, function

J. E. Gadek, G. A. Fells, D. G. Wright, and R. G. Crystal. Human neutrophil elastase functions as a type III collagen collagenase. Biochem. Biophys. Res. Comm. 98 1815(1980). 

There are other substrates for the E. coli Met(0) peptide reductase, one of which is Met(0)-a-l-PI. The native protein is the major serum elastase inhibitor that functions by forming a binary complex with elastase which inhibits its activity. Met(0)-a-l-PI, on the other hand, which can be formed by treatment of the protein with TV-chlorosuccinimide, cannot form a complex with elastase and therefore is not able to inhibit elastase activity117,118. Table 6 shows, however, that when Met(0)-a-l-PI is incubated in the presence of Met(0)-peptide reductase and dithiothreitol the protein regains its ability to form a complex with elastase and inhibit elastase activity119. Similar to results found with Met(0)-L12 reduced thioredoxin could replace the dithiothreitol as reductant in the enzymatic reaction. 

The serine proteases are the most extensively studied class of enzymes. These enzymes are characterized by the presence of a unique serine amino acid. Two major evolutionary families are presented in this class. The bacterial protease subtilisin and the trypsin family, which includes the enzymes trypsin, chymotrypsin, elastase as well as thrombin, plasmin, and others involved in a diverse range of cellular functions including digestion, blood clotting, hormone production, and complement activation. The trypsin family catalyzes the reaction ... 

Leukocyte elastase 4-67 No CXCR4 binding/ function/loss anti-HIV Valenzuela-Femandez et al. (2002)... 

Doucet, C. Vergely, I. Reboud-Ravaux, M. Guilhem, J. Kobaiter, R. Joyeau, R. Wakselman, M. Inhibition of human leucocyte elastase by functionalized V-aryl azeti-din-2-ones. Stereospecific synthesis and chiral recognition of disymmetrically C3-substi-tuted P-lactams. Tetrahedron Asymmetry 1997, 8, 739-751. 

Joyeau, R. Felk, A. Guillaume, S. Vergely, I. Doucet, C. Boggetto, N. Reboud-Ravaux, M. Synthesis and inhibition of human leucocyte elastase by functionalized V-aryl azetidin-2-ones effect of different substituents on the aromatic ring. J. Pharm. Pharmacol. 1996, 48, 1218-1230. 

Valenzuela-Femandez A, Planchenault T, Baleux F, et al. Leukocyte elastase negatively regulates Stromal cell-derived factor-1 (SDF-1)/CXCR4 binding and functions by amino-terminal processing of SDF-1 and CXCR4. J Biol Chem 2002 277(18) 15677-15689. 

This approach has been mainly applied to peptide-based inhibitors of proteases, where the inhibitory molecule is a peptide with a transition state isostere appended to it, and the cognate substrate is simply a peptide of the same amino acid sequence, but lacking the isostere functionality. Examples where good correlations between the free energy of inhibitor binding and the free energy of kcJKM have been found, include peptide-trifluoromethyl ketone inhibitors of human leukocyte elastase (Stein et al., 1987) and peptide-phosphonamidate inhibitors of the metalloprotease ther-molysin (Bartlett and Marlowe, 1983). 

This is a 29-kDa protein that has NH 2-terminal sequence homology with elastase and cathepsin G. However, it contains glycine and not serine at the predicted catalytic site, and so lacks protease and peptidase activity. Purified azurocidin kills a range of organisms (e.g. E. coli, S.faecalis, and C. albicans) in vitro. It functions optimally at pH 5.5 and in conditions of low ionic strength. 

In addition to the aforementioned allenic steroids, prostaglandins, amino acids and nucleoside analogs, a number of other functionalized allenes have been employed (albeit with limited success) in enzyme inhibition (Scheme 18.56) [154-159]. Thus, the 7-vinylidenecephalosporin 164 and related allenes did not show the expected activity as inhibitors of human leukocyte elastase, but a weak inhibition of porcine pancreas elastase [156], Similarly disappointing were the immunosuppressive activity of the allenic mycophenolic acid derivative 165 [157] and the inhibition of 12-lipoxygenase by the carboxylic acid 166 [158]. In contrast, the carboxyallenyl phosphate 167 turned out to be a potent inhibitor of phosphoenolpyruvate carboxylase and pyruvate kinase [159]. Hydrolysis of this allenic phosphate probably leads to 2-oxobut-3-enoate, which then undergoes an irreversible Michael addition with suitable nucleophilic side chains of the enzyme. 

The mammalian serine proteases have a common tertiary structure as well as a common function. The enzymes are so called because they have a uniquely reactive serine residue that reacts irreversibly with organophosphates such as diisopropyl fluorophosphate. The major pancreatic enzymes—trypsin, chymotrypsin, and elastase—are kinetically very similar, catalyzing the hydrolysis of peptides... 

Salter, J.P., Choe, Y., Albrecht, H., Franklin, C., Lim, K.C., Craik, C.S. and McKerrow, J.H. (2002) Cercarial elastase is encoded by a functionally conserved gene family across multiple species of schistosomes. 

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