Elastases properties

A significant advance in the understanding of the anti-inflammatory properties of Bupleurum fruticescens has been provided by Prieto et al. (36). The showed that a methanol extract from the aerial parts had a significant effect on 5-lipoxygenase activity, inhibiting both LTB4 and 5(S)-HETE production, with IC50 values of 112 and 95 (xg/mL, respectively. At concentrations of 200 (Xg/mL, the extract inhibited COX-1 (90%) and elastase activities (54%). What are the principles involved here, saponin ... 

Several of the postulated roles for nematode-secreted AChEs assume that they gain access to the intestinal mucosa. Several possibilities exist for transport of parasite AChE across the epithelial cell barrier, such as (i) utilization of existing pathways for receptor-mediated transcytosis (ii) a paracellular route facilitated by parasite-secreted proteases as observed for a bacterial elastase (Azghani et al., 1993) and (iii) increased paracellular permeability resulting from inflammatory events in the mucosa. We consider the latter suggestion most likely, as this has been duplicated by ex vivo perfusion with rat mast cell protease II (Scudamore et al., 1995). Moreover, cholinergic stimulation attenuates epithelial barrier properties to macromolecules in rat ileal crypts (Phillips et al., 1987). 

A different strategy for measuring protease activity is based on the property of xanthene dyes to form H-type dimers (see Sect. 6.2.3) when they are in close proximity. These dimers are accompanied with a characteristic quenching of their fluorescence and, particularly for rhodamines, with a blue shift in the absorption spectrum [121, 122]. The probe D-NorFES-D designed to measure activity of elastase in HL-60 cells consists of an undecapeptide derivatized with one tetramethylrhodamine dye on each side. The sequence contains proline residues to create a bent structure and bring the two fluoro-phores in close proximity. Intact D-NorFES-D shows 90% of its fluorescence quenched plus a blue shift of the absorption spectrum. After addition of the serine protease elastase, an increase in the fluorescence and a bathochromic shift of the absorption spectrum is observed, resulting in an increase in the emission ratio [80],... 

Alpha-1 A protein with the property of inactivating proteolytic enzymes such as leucocyte collagenase and elastase. [NIH]... 

Relevant heparin-binding enzymes not involved in the coagulation cascade are, for example, elastase, cathepsin G, superoxide dismutase, lipoprotein lipase and other lipases. The plasma clearing properties of heparin are associated with its binding to lipoprotein lipase and hepatic lipase when the enzymes are released from the surface of endothelial cells [11] and have been studied in view of a potential impact on the regulation of atherosclerosis. 

The substrate specificity of an enzyme is determined by the properties and spatial arrangement of the amino acid residues forming the active site. The serine proteases trypsin, chymotrypsin and elastase cleave peptide bonds in protein substrates on the carboxyl side of positively charged, aromatic and small side-chain amino acid residues, respectively, due to complementary residues in their active sites. 

The properties and spatial arrangement of the amino acid residues forming the active site of an enzyme will determine which molecules can bind and be substrates for that enzyme. Substrate specificity is often determined by changes in relatively few amino acids in the active site. This is clearly seen in the three digestive enzymes trypsin, chymotrypsin and elastase (see Topic C5). These three enzymes belong to a family of enzymes called the serine proteases - serine because they have a serine residue in the active site that is critically involved in catalysis and proteases because they catalyze the hydrolysis of peptide bonds in proteins. The three enzymes cleave peptide bonds in protein substrates on the carboxyl side of certain amino acid residues. 

Diazetidin-2,4-dione has been found to be a chymase inhibitor (IC50 4.0nM). It has been found that 1,3-diazetidin-2,4-dione derivatives possess high activities against bovine pancreatic cr-chrymotrypsin, human cathepsin G, and human neutrophil elastase. Some of the derivatives of l,3-diazetidin-2,4-diones have been shown to be effective as a scaffold for serine protease inhibitors <2001BML1691>. Further, 1,3-diazetidinone containing scaffolds have been found to possess potential antibacterial properties (Section 2.13.7.3). 

Like SLPI, elafin is a very potent inhibitor of NE. Elafin interacts with elastase in a reversible manner and retains its inhibitory capacity upon dissociation of the complex. Kinetic data have shown that the association rate constant for the formation of an elafin-elastase complex is pH dependent [84]. Una is probably due to the bask properties of the inhibitor and enzyme. Elafin also inhibits proteinase 3 but has no effect on cathepsin G, trypsin, or chymotrypsin. This is inloestiitg in view of the fact that SLPI inhibits cathepsin G but la relatively ineffective against proteinase 3. 

The role of therapeutic inhibitors of elastase is to prevent the degradation of extracellular matrix proteins following the release of elastase from activated neutrophils. Tb determine which inhibitors of elastase may be of therapeutic value, there are several properties that must be considoed. These include rate of wmnMjnaaw tmrjivsti , selectivity, ize, tn vnHKi i y to rnBCtiv inn ... 

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... 

Simmen, R. C. M., Michel, F. J., M., Fliss, A. E., Smith, L. C., and Ventura-Fliss, M. F. (1992). Ontogeny, immunocytochemical localization, and biochemical properties of the pregnancy-associated uterine elastase/cathepsin-G protease inhibitor, antileukoproteinase (ALP) Monospecific antibodies to a synthetic peptide recognize native ALP. Endocrinology (Baltimore) 130, 1957-1965. 

Elastase prefers elastin as substrate if it is anionic in character, which is the case when anionic detergents or fatty acids are bound to elastin. Cationic detergents do not stimulate elastolysis. From the standpoint of elastin turnover in vivo a property of the protein which may provide protection from proteolytic enzymes resembling elastase is its cationic character (57,58). In fact, a significant feature of the protein that may protect against normal elastolysis is the observation that over 70% of the glutamyl and aspartyl residues in the protein appear to be amidated (58). 

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