Cathepsin G

Cathepsins are intracellular proteinases that reside within lysosomes or specific intracellular granules. Cathepsins are used to degrade proteins or pqffides that are internalised from the extracellular space. Some cathepsins such as cathepsin-G or cathepsin-K may be released from the cell to degrade specific extracellular matrix proteins. All cathepsins except cathepsin-G (serine) and cathepsin-D (aspartyl) are cysteine proteinases. 

Chymotrypsin-like proteinases are serine proteinases that recognize pqDtide residues with aromatic side chains (phyenylalanyl or tyrosyl residues) and that effect hydrolysis of the polypeptide chain on the carboxy-terminal side of these residues. Examples of chymotrypsin-like proteinases are chymotrypsin and cathepsin-G. 

Besides AT, heparin cofactor II (HCII) is an antic-oagulatory protein enhanced by heparin. HCII inactivates thrombin and the nonclotting enzymes cathepsin-G and chymotrypsin. 

CD26/DPPIV Elastase/ cathepsin G/ plasmin 3-74 Partial CCR3 antag. Oravecz et al. (1997), Struyfetal. (1999) EUyard et al. (2007)... 

CCL23 Cathepsin G/ chymase 27-99 Inc. CCRl activity Berahovich et al. (2005)... 

CAH Chronic active hepatitis CALLA Common lymphoblastic leukaemia antigen CALX Conjunctival associated lymphoid tissue CaM Calmodulin cAMP Cyclic adenosine monophosphate also knomt as adenosine 3, 5 -phosphate CAM CeU adhesion molecule CAP57 Cationic protein from neutrophils CAT Catalase CatG Cathepsin G... 

Serine proteases usually show primary specificity (occupation of subsite Si) for positively charged arginine or lysine (trypsin, plasmin, plasminogen activators, thrombin), large hydrophobic side chains of phenylalanine, tyrosine, and tryptophan (chymotrypsin, cathepsin G, chymase, and subtilisin), or small aliphatic side chains (elastases). Nevertheless, there are a large number of variations and in many cases, other subsites like S2 and S3 are more discriminating while maintaining the... 

Eosinophils may be increased in some patients, particularly during exacerbations. Activated inflammatory cells release a variety of mediators, most notably leukotriene B4, interleukin-8, and tumor necrosis factor-a (TNF-a). Various proteinases, such as elastase, cathepsin G, and proteinase-3, are secreted by activated neutrophils. These mediators and proteinases are capable of sustaining inflammation and damaging lung structures. 

Cathepsin G, a cationic, glycosylated protein of relative molecular mass -27 kDa, exists in four isoforms (25-29 kDa) that are identical in amino acid sequence but differ in levels of glycosylation. It is a component of azurophilic granules and present in human neutrophils at 1.5-3 jug/106 cells, but at lower levels in monocytes. cDNA has been cloned and sequenced (and the amino acid sequence predicted), and the gene has been localised to chromosome 14ql 1.2. The gene comprises five exons and four introns, a structure similar to that of the elastase gene. 

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. 

C5a is inactivated by the myeloperoxidase-H202 system, which oxidises a methionine residue (Met 70) on the molecule group A streptococcal endo-proteinases also abolish chemotactic activity of C5a and related compounds. Neutrophil lysosomal enzymes (e.g. elastase and cathepsin G) also destroy C5a chemotactic activity, but as these proteases are inhibited by the serum antiproteinases, a -antiproteinase and a2-macroglobulin, the physiological role of neutrophilic proteases in the inactivation of C5a is questionable. Two chemotactic factor inactivators have been found in human serum an a-globulin that specifically and irreversibly inactivates C5-derived chemotactic factors, and a / -globulin that inactivates bacterial chemotactic factors. These activities are heat labile (destroyed by treatment at 56 °C for 30 min) and are distinct from those attributable to anaphylatoxin inactivator. An apparently specific inhibitor of C5-derived chemotactic activity has also been described in human synovial fluid and peritoneal fluid. This factor (molecular mass of 40 kDa) is heat stable and acts directly on C5a. 

Tervahartiala T, Konttinen YT, Ingman T, Hayrinen-Immonen R, Ding Y and Sorsa T (1996) Cathepsin G in gingival tissue and crevicular fluid in adult periodontitis. J Clin Period 23, 68-75. 

Selected entries from Methods in Enzymology [vol, page(s)] Sulfonylation reaction, 11, 706 reaction kinetics, 11, 707 second-order rate constants for inactivation of chymotrypsin, trypsin, and acetylcholine esterase by PMSE and related sulfonylat-ing agents, 11, 707 reactivation of PMS-chymotrypsin, 11, 710 as inhibitor [of calcium-activated factor, 80, 674 of cathepsin G, 80, 565 of crayfish trypsin, 80, 639 of elastase, 80, 587 of pro-lylcarboxypeptidase, 80, 465 of protease Re, 80, 691 of protease So, 80, 695 of protein C, 80, 329] proteolysis, 76, 7. 

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