Proteases leukocyte

Finally, coumarin derivatives may act as general inhibitors of serine proteases or as specific inhibitors of human leukocyte elastase, depending on the nature of the substituents, through two distinct mechanisms, suicide substrates (a-chymotrypsin)... 

The acyl-enzyme can eliminate the 4-chlorine atom to generate this reactive intermediate that can then react with a nearby nucleophile such as His57 to give an alkylated acyl-enzyme derivative in which the inhibitor moiety is bound to the enzyme by two covalent bonds (Scheme 11.5). Inhibition is irreversible.59 The mechanism has been confirmed by X-ray structural analysis of protease-isocoumarin complexes. There is a cross-link between the inhibitor and the Serl95 and His57 residues of PPE.60 Human leukocyte elastase is also very efficiently inactivated.61... 

Human leukocyte elastase is a protease that degrades elastin and other connective tissue components. It is implicated in the pathogenesis of pulmonary emphysema and other inflammatory diseases such as rheumatoid arthritis and cystic fibrosis. Porcine pancreatic elastase has often been used as a model for HLE. Both enzymes have a small primary binding site Si. 

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). 

Based on the mixed-phase method, ACE is introduced for studying the interaction of heparin with the serine protease inhibitors, antithrombin III (ATIII) and secretory leukocyte proteinase inhibitor (SLPI) (85). An etched capillary, to which heparin has been covalently immobilized, was used in this study. This modified capillary both afforded an improvement in the separation of heparin-binding proteins and required a lower quantity of loaded protein. 

MA Fath, X Wu, RE Hileman, RJ Linhardt, MA Kashem, RM Nelson, CD Wright, WM Abraham. Interaction of secretary leukocyte protease inhibitor with heparin inhibits protease involved in asthma. J Biol Chem 273 13563— 13569, 1998. 

Very recently, (3-lactam antibiotics have been shown to offer neuroprotection by increasing glutamate transporters expression via gene activation [15] in addition, the discoveries of new biologically active (3-lactams such as cholesterol acyl transferase inhibitors [16-18], thrombin inhibitors [19], human cytomegalovirus protease inhibitors [20], matrix-metallo protease inhibitors [21], inhibitors of human leukocyte elastase (HLE) [22, 23] and cysteine protease [24, 25], and apoptosis inductors [26, 27] have provided much needed motivation for continuous development of new (3-lactam systems. 

Torriglia, A., Perani, P., Borssas, J., Chaudun, E., Treton, J., Courtois, Y. and Counis, M.-F. (1998) L-DNasell, a molecule that links proteases and endonucleases in apoptosis, derives from the ubiquitous Serpin Leukocyte Elastase Inhibitor. Mol. Cell. Biol, 18, 3612-3619. 

Wright, C.D., J.A. Kennedy, R.J. Zitnik, and M.A. Kashem. 1999. Inhibition of murine neutrophil serine proteinases by human and murine secretory leukocyte protease inhibitor. Biochem. Biophys. Res. Commun. 254 614—617. 

Like antithrombin, heparin cofactor II inhibits proteases by forming a I I stoichiometric complex with the enzyme. The protease attacks the reactive site of heparin cofactor II located on the C-terminus, resulting in the formation of a covalent bond. Heparin cofactor II has higher protease specificity than antithrombin. Of the coagulation enzymes, heparin cofactor II is known only to inhibit thrombin (92). Additionally heparin cofactor II has been shown to inhibit chymotrypsin (93) and leukocyte cathepsin G (94), This protease specificity appears to be due to the active site bond present in heparin cofactor II. Whereas antithrombin contains an Arg-Ser bond as its active site, heparin cofactor II is unique in containing a Leu-Ser bond. This suggests than another portion of the heparin cofactor II molecular may be required for protease binding,... 

J. A. McDonald, B. J. Baum, D, M. Roseubeg, J. A. Kdman,S. C. Brin, and R. G. Crystal. Destruction of a imJor extracellular adhesive glycoprotein (fibronccrin) of human fibroblasts by neutral proteases from polymorphonuclear leukocyte granules. Lab. Invest. 40350 (1979). 

G. Stetler. M. T, Brewer, and R, C Thompson. Isolation and sequence of a human gene encoding a potent inhibitor of leukocyte proteases. JVecJL Acid As. J4 7883... 

E. C. Luccy, P. J. Stone. D. EL Ciccolclla, R. Bcuer, T. 0. Christensen, R. C. Thompson, and G- L. Snider. Recombinant human secretory leukocyte-protease inhibitor in vitro properties, and amelioration of human neutrophil elastase-induced emphysema and secretory cell metaplasia in the hamster. /. Lab. Clin. hied. 7/5 224... 

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