Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01034 (cystatin C)
 3,397 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The high-Mr alkali-stable form of cathepsin B was purified from purulent human sputum. It was shown to solubilize proteoglycan monomer entrapped in polyacrylamide at a rate comparable with that of human lysosomal cathepsin B. Like the enzyme from lysosomes, sputum cathepsin B was bound by human alpha 2-macroglobulin, which inhibited its action on proteoglycan. Cystatin C in purulent sputum was shown to be the N-terminally truncated form generated by neutrophil elastase cleavage, and sputum cathepsin B was only weakly inhibited by recombinant cystatin C that had been cleaved by neutrophil elastase in vitro. Addition of neutrophil elastase to mucoid sputum led to a 5-fold increase in cathepsin B activity concomitant with a lowering in Mr of the cysteine proteinase from 40,000 to 37,000, i.e. the size of the active enzyme purified from purulent sputum. It is concluded that the high-Mr form of cathepsin B present in purulent sputum is a functional proteinase, unlike similar forms of the enzyme secreted by mammary gland in organ culture. The activity of cathepsin B in sputum is modulated by neutrophil elastase, by a combination of inhibitor inactivation and zymogen activation.
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PMID:Human sputum cathepsin B degrades proteoglycan, is inhibited by alpha 2-macroglobulin and is modulated by neutrophil elastase cleavage of cathepsin B precursor and cystatin C. 171 Aug 89

The effect of four human serine proteinases on the human cysteine proteinase inhibitor, cystatin C, has been studied in vitro. Neutrophil elastase in catalytic amounts was observed to rapidly cleave cystatin C at neutral pH, thereby giving rise to a modified form of the inhibitor lacking the N-terminal Ser1-Val10 decapeptide. The two other leukocyte serine proteinases, cathepsin G and neutrophil proteinase 4, did not catalytically hydrolyse cystatin C bonds. Neither had the seminal plasma serine proteinase, prostate-specific antigen, any effect on cystatin C. The physiological implications of neutrophil elastase catalysed modification of cystatin C are discussed, and recent findings indicating that this reaction also occurs in vivo are reviewed.
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PMID:Regulation of cystatin C activity by serine proteinases. 180 27

Sputum samples from 25 patients with bronchiectasis were assayed enzymatically for myeloperoxidase, neutrophil elastase and cathepsin B, and immunologically for cystatin A, cystatin B, cystatin C, cystatin S and kininogen. High myeloperoxidase and neutrophil elastase levels were found in those sputum samples that were assessed visually to be purulent. These samples were also found to contain high levels of cathepsin B activity and cystatin A, but low levels of cystatin S and of the most effective cathepsin B inhibitor, cystatin C. In contrast, sputum samples that were low in myeloperoxidase and neutrophil elastase activities had low levels of cathepsin B and cystatin A, but high cystatin C and S levels. It is concluded that cathepsin B activity in sputum is positively correlated with the degree of inflammation and neutrophil recruitment. Although this may be due in part to reduced amounts of cathepsin B inhibitors, particularly cystatin C, theoretical considerations suggest that factors other than the gross level of inhibitors must be involved in the control of cathepsin B activity.
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PMID:Levels of neutrophil elastase and cathepsin B activities, and cystatins in human sputum: relationship to inflammation. 223 63

Staphylococcus aureus is known to produce three very active extracellular proteinases. One of these enzymes, a cysteine proteinase, after purification to homogeneity was found to degrade insoluble bovine lung elastin at a rate comparable to human neutrophil elastase. This enzyme had no detectable activity against a range of synthetic substrates normally utilized by elastase, chymotrypsin, or trypsin-like proteinases. However, it did hydrolyze the synthetic substrate carbobenzoxy-phenylalanyl-leucyl-glutamyl-p-nitroanilide (Km = 0.5 mM, kcat = 0.16 s-1). The proteolytic activity of the cysteine proteinase was rapidly and efficiently inhibited by alpha 2-macroglobulin and also by the cysteine-specific inhibitor rat T-kininogen (Ki = 5.2 X 10(-7) M). Human kininogens, however, did not inhibit. Human plasma apparently contains other inhibitors of this enzyme, since plasma depleted of alpha 2-macroglobulin retained significant inhibitory capacity. The elastolytic activity of this S. aureus proteinase and its lack of control by human kininogens or cystatin C may explain some of the connective tissue destruction seen in bacterial infections due to this and related organisms such as may occur in septicemia, septic arthritis, and otitis.
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PMID:Degradation of elastin by a cysteine proteinase from Staphylococcus aureus. 342 37

Procathepsin B and cystatin C are found in human lung secretions. We investigated the capacity of human bronchial epithelial cells to synthesize and secrete these proteins. Immunoprecipitation of [35S]methionine-labeled proteins from cultured bronchial epithelial cell lysates, followed by denaturing gel electrophoresis and autoradiography, showed the presence of newly synthesized procathepsin B of M(r) 42,000; no mature form was detected. Cathepsin B in conditioned medium from epithelial cells was tagged with benzyloxycarbonyl-125I-tyrosyl-alanine-diazomethane before and after treatment of the medium with neutrophil elastase. Control medium again showed a predominant form of cathepsin B with a M(r) of 42,000, but upon treatment with neutrophil elastase this protein was converted to a M(r) of 38,000, similar to the active form previously found in lung secretions, and cathepsin B activity was generated. The medium also contained the cathepsin B inhibitor, cystatin C, but cystatins A, B, S, SN, SA, and kininogen were not detected. After removal of cystatin C from the medium, elastase was still required to activate procathepsin B. These results suggest that bronchial epithelial cells are a source of procathepsin B and cystatin C in lung secretions. Cleavage both of cystatin C and procathepsin B by neutrophil elastase is essential for the generation of cathepsin B activity in the medium.
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PMID:Synthesis and secretion of procathepsin B and cystatin C by human bronchial epithelial cells in vitro: modulation of cathepsin B activity by neutrophil elastase. 787 98

The lysosomal cysteine proteinase cathepsin B is shown to be secreted by ten human colon carcinoma cell lines and to accumulate in culture media as a latent enzyme. The cell lines also secrete a physiological inhibitor of cathepsin B, cystatin C. A significant correlation was found between secretion of the latent enzyme and the inhibitor (r = 0.755, P < 0.01). The aim of the present study was to modulate the respective secretion of the two antagonists to test whether or not latency of cathepsin B was due to the concomitant secretion of the inhibitor. SW480 colon carcinoma cells were treated with the acidotropic agent ammonium chloride, phorbol 12-myristate 13-acetate, and the inflammatory cytokines TGF-beta, TNF-alpha, and IL-1 beta. Ammonium chloride significantly increased latent cathepsin B levels without affecting the constitutive secretion of cystatin C. Phorbol 12-myristate 13-acetate induced a 4- to 5-fold increase in secreted latent cathepsin B, but did not alter significantly the accumulation of cystatin C in media. The cytokines, TGF-beta, TNF-alpha, and IL-1 beta, had no major effect on the expression of these two antagonists. Latent cathepsin B released from human carcinoma cells could be efficiently activated by neutrophil elastase at neutral pH. It is concluded that latent cathepsin B is a true proenzyme rather than an enzyme-inhibitor complex. In addition, our data from neutrophil elastase activation experiments indicate that a proteolytic system for activation of the tumor cell-secreted latent enzyme may exist in vivo.
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PMID:Latency of cathepsin B secreted by human colon carcinoma cells is not linked to secretion of cystatin C and is relieved by neutrophil elastase. 820 57

Human cystatin C variants in which the evolutionarily conserved Gly-11 residue has been replaced by residues with positively charged (Arg), negatively charged (Glu), bulky hydrophobic (Trp), or small (Ser or Ala) side-chains have been produced by site-directed mutagenesis and expression in Escherichia coli. The five variants were isolated and structurally verified. Their inhibitory properties were compared with those of wild-type recombinant cystatin C by determination of the equilibrium constants for dissociation (Ki) of their complexes with the cysteine endopeptidases papain and human cathepsin B and with the cysteine exopeptidase dipeptidyl peptidase I. The Ser-11 and Ala-11 cystatin C variants displayed Ki values for the two endopeptidases that were approx. 20-fold higher than those of wild-type cystatin C, while the corresponding values for the Trp-11. Arg-11 and Glu-11 variants were increased by a factor of about 2000. In contrast, the Ki values for the interactions of all five variants with the exopeptidase differed from that of wild-type cystatin C by a factor of less than 10. Wild-type cystatin C and the Ser-11, Ala-11 and Glu-11 variants were incubated with neutrophil elastase, which in all cases resulted in the rapid hydrolysis of a single peptide bond, between amino acid residues 10 and 11. The Ki values for the interactions with papain of these three N-terminal-decapeptide-lacking cystatin C variants were 20-50 nM, just one order of magnitude higher than the value for N-terminally truncated wild-type cystatin C, which in turn was similar to the corresponding values for the full-length Glu-11, Arg-11 and Trp-11 variants. These data indicate that the crucial feature of the conserved Gly residue in position 11 of wild-type cystatin C is that this residue, devoid of a side-chain, will allow the N-terminal segment of cystatin C to adopt a conformation suitable for interaction with the substrate-binding pockets of cysteine endopeptidases, resulting in high-affinity binding and efficient inhibition. The functional properties of the remaining part of the proteinase contact area, which is built from more C-terminal inhibitor segments, are not significantly affected even when amino acids with bulky or charged side-chains replace the Gly-11 residue of the N-terminal segment.
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PMID:Importance of the evolutionarily conserved glycine residue in the N-terminal region of human cystatin C (Gly-11) for cysteine endopeptidase inhibition. 847 Oct 31

This study examined the role of cysteine proteinases and their inhibitor in the development of emphysema in comparison with neutrophil elastase (NE) complexed with alpha1-protease inhibitor (NE-alpha1-PI), which was previously demonstrated to be increased in bronchoalveolar lavage (BAL) fluid from subjects with subclinical emphysema. Eight nonsmokers and 31 current smokers with (n=17) and without (n=14) emphysema, as evidenced by lung computed tomographic scans, were studied. The concentrations of immunologically detected cathepsin L and cystatin C, but not cathepsin B, were significantly increased in BAL fluid from the smokers with emphysema compared with those without emphysema, although the activity of cathepsin L, measured using a synthetic substrate and cathepsin L, released from cultured alveolar macrophages at 24 h, did not show any significant difference between the two groups. When comparison was made only for the subjects aged <60 yrs, the difference between the two groups disappeared for cathepsin L, but remained for NE-alpha1-PI. There was no significant correlation between the level of cathepsin L and that of NE-alpha1-PI in BAL fluid from the subjects with emphysema. In conclusion, increased levels of cathepsin L and cystatin C were demonstrated in bronchoalveolar lavage fluid from subjects with subclinical emphysema. However, the roles of cathepsin L and neutrophil elastase in the development of emphysema may vary between subjects and between the young and the old.
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PMID:Cysteine proteinases and cystatin C in bronchoalveolar lavage fluid from subjects with subclinical emphysema. 986 93

Recent studies have shown that the bovine cysteine proteinase inhibitor, cystatin C, is synthesized as a preprotein containing a 118-residue mature protein. However, the forms of the inhibitor isolated previously from bovine tissues had shorter N-terminal regions than expected from these results, and also lower affinity for proteinases than human cystatin C. In this work, we report the properties of recombinant, full-length bovine cystatin C having a complete N-terminal region. The general characteristics of this form of the inhibitor, as reflected by the isoelectric point, the far-ultraviolet circular dichroism spectrum, the thermal stability and the changes of tryptophan fluorescence on interaction with papain, resembled those of human cystatin C. The affinity and kinetics of inhibition of papain and cathepsins B, H and L by the bovine inhibitor were also comparable with those of the human inhibitor, although certain differences were apparent. Notably, the affinity of bovine cystatin C for cathepsin H was somewhat weaker than that of human cystatin C, and bovine cystatin C bound to cathepsin L with about a four-fold higher association rate constant than the human inhibitor. This rate constant is comparable with the highest values reported previously for cystatin-cysteine proteinase reactions. The full-length, recombinant bovine cystatin C bound appreciably more tightly to proteinases than the shorter form characterized previously. Digestion of the recombinant inhibitor with neutrophil elastase resulted in forms with truncated N-terminal regions and appreciably decreased affinity for papain, consistent with the forms of bovine cystatin C isolated previously having arisen by proteolytic cleavage of a mature, full-length inhibitor.
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PMID:The affinity and kinetics of inhibition of cysteine proteinases by intact recombinant bovine cystatin C. 1036 30

Cystatin C, a major extracellular cysteine proteinase inhibitor, is deposited as amyloid in brain haemorrhage patients with hereditary cystatin C amyloid angiopathy (HCCAA). A disease-causing mutation on the genetic level results in the substitution Leu68-->Gln (L68Q) in cystatin C, which causes protein instability. Besides carrying the L68Q substitution, cystatin C in amyloid deposits isolated from patients is N-terminally truncated by 10 amino acids. To elucidate the role of the N-terminal truncation for protein stability and aggregation properties, (delta1-10,L68Q)-cystatin C was produced in an Escherichia coli expression system and characterised. Unlike wild-type cystatin C, this variant rapidly dimerised under physiological conditions. Two unfolding intermediates of (delta1-10,L68Q)-cystatin C were identified, under the same pH and ionic strength conditions as required to form intermediates of full-length L68Q cystatin C. No evidence was found that the N-terminal truncation per se alters protein stability and leads to higher forms of aggregation. Monomeric as well as dimeric L68Q cystatin C incubated with neutrophil elastase was truncated as in HCCAA patients' amyloid. A protein variant with a thrombin cleavage site placed in front of residue Gly11 in L68Q cystatin C was constructed and used to confirm that the N-terminal segment is similarly accessible to proteinases in the monomeric and dimeric states of L68Q cystatin C. Thus, the N-terminal segment of L68Q cystatin C is exposed to proteolytic attack and does not seem to be involved in intramolecular contacts leading to dimerisation or higher-order aggregation. We conclude that the N-terminal truncation likely is an event secondary to amyloid formation, and of no relevance for the development of HCCAA.
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PMID:Physico-chemical properties of the N-terminally truncated L68Q cystatin C found in amyloid deposits of brain haemorrhage patients. 1193 68


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