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)

An alkaline unwinding assay was used to quantitate the induction of DNA strand breaks (DNA SB) in the livers of rats and mice treated in vivo, in rodent hepatocytes in primary culture, and in CCRF-CEM cells, a human lymphoblastic leukemia cell line, following treatment with tri- (TCA), di- (DCA), and mono- (MCA) chloroacetic acid and their corresponding aldehydes, tri- (chloral hydrate, CH), di- (DCAA) and mono- (CAA) chloroacetaldehyde. None of the chloroacetic acids induced DNA SB in the livers of rats at 4 hr following a single administration of 1-10 mmole/kg. TCA (10 mmole/kg) and DCA (5 and 10 mmole/kg) did produce a small amount of strand breakage in mice (7% at 4 hr) but not at 1 hr. N-nitrosodiethylamine (DENA), an established alkylating agent and a rodent hepatocarcinogen, produced DNA SB in the livers of both species. TCA, DCA, and MCA also failed to induce DNA strand breaks in splenocytes and epithelial cells derived from the stomach and duodenum of mice treated in vivo. None of the three chloroacetaldehydes induced DNA SB in either mouse or rat liver. The continuous exposure of mice to 5 g/L DCA in the drinking water for 7 and 14 days did not induce appreciable hepatic DNA SB (< 10% at 14 days), although peroxisome proliferation, as evidenced by an increased cyanide-insensitive palmitoyl CoA oxidase (PCO) activity, was stimulated to 490% (7 days) and 652% (14 days) of control. Under this protocol, DENA (0.1 g/L) produced DNA damage after both 7 days (73% of control) and 14 days (57% of control). Similarly, long-term exposure of rats (30 weeks) to 2 g/L DCA in the drinking water, a level that increased PCO activity to 364% of the control value, exhibited no DNA damage. Both the chloroacetic acids and the chloroacetaldehydes were ineffective in inducing DNA SB in cultured rat and mouse hepatocytes at concentrations below those that yielded cytotoxicity. The chloroacetic acids were also ineffective in the CCRF-CEM cells. However, two of the chloroaldehydes, DCAA and CAA, did induce DNA SB in the CCRF-CEM cells at concentrations that did not decrease the cell viability after 2 hr of treatment. Prior incubation of DCAA and CAA with a rat S9 liver homogenate eliminated much of the DNA damaging activity. These studies provide further evidence that the chloroacetic acids lack genotoxic activity not only in rodent liver, a tissue in that they induce tumors, but in a variety of other roden tissues and cultured cell types.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Analysis of DNA strand breaks induced in rodent liver in vivo, hepatocytes in primary culture, and a human cell line by chlorinated acetic acids and chlorinated acetaldehydes. 133 May 47

'Prohormone thiol protease' (PTP) represents the major enkephalin precursor processing activity in chromaffin granules. In this study, cleavage specificity of PTP for paired basic and monobasic residues was examined with a series of model peptide-MCA (-methylcoumarinamide) substrates. Monobasic peptides were cleaved at the COOH- and NH2-terminal sides of the single basic residue. Dibasic peptides, however, were preferentially cleaved at the NH2-terminal side of the pair, or between the two basic residues, with low cleavage at the COOH-terminal side of the pair. Inhibition by the peptide inhibitor (D-Tyr)-Glu-Phe-Lys-Arg-CH2Cl provided further evidence for PTP's specificity for the dibasic Lys-Arg site. Inhibition by Z-Leu-Val-Gly-CHN2 and Z-Arg-Leu-Val-Gly-CHN2 suggests involvement of Val-Gly in substrate binding to PTP; these two cystatin C-related inhibitors also indicate PTP as a cysteine protease. These results demonstrate PTP's unique cleavage specificity that differs from other processing endopeptidases, including the subtilisin-related proprotein convertases, PC1/PC3, and PC2, as well as the pituitary proopiomelanocortin-converting enzyme, PCE. This study provides further evidence for PTP as a novel prohormone processing enzyme that belongs to the class of cysteine proteases.
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PMID:Unique cleavage specificity of 'prohormone thiol protease' related to proenkephalin processing. 813 39

Cathepsin X is a novel cysteine protease which was identified recently from the EST (expressed sequence tags) database. In a homology model of the mature cathepsin X, a unique three residue insertion between the Gln22 of the oxyanion hole and the active site Cys31 was found to be located in the primed region of the binding cleft as part of a surface loop corresponding to residues His23 to Tyr27, which we have termed the "mini-loop". From the model, it became apparent that this distinctive structural feature might confer exopeptidase activity to the enzyme. To verify this hypothesis, human procathepsin X was expressed in Pichia pastoris and converted to mature cathepsin X using small amounts of human cathepsin L. Cathepsin X was found to display excellent carboxypeptidase activity against the substrate Abz-FRF(4NO(2)), with a k(cat)/K(M) value of 1.23 x 10(5) M(-)(1) s(-)(1) at the optimal pH of 5.0. However, the activity of cathepsin X against the substrates Cbz-FR-MCA and Abz-AFRSAAQ-EDDnp was found to be extremely low, with k(cat)/K(M) values lower than 70 M(-)(1) s(-)(1). Therefore, cathepsin X displays a stricter exopeptidase activity than cathepsin B. No inhibition of cathepsin X by cystatin C could be detected up to a concentration of 4 microM of inhibitor. From a model of the protease complexed with Cbz-FRF, the bound carboxypeptidase substrate is predicted to establish a number of favorable contacts within the cathepsin X binding site, in particular with residues His23 and Tyr27 from the mini-loop. The presence of the mini-loop restricts the accessibility of cystatin C as well as of the endopeptidase and MCA substrates in the primed subsites of the protease. The marked structural and functional differences of cathepsin X relative to other members of the papain family of cysteine proteases will be of great value in designing specific inhibitors useful as research tools to investigate the physiological and potential pathological roles of this novel enzyme.
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PMID:Human cathepsin X: A cysteine protease with unique carboxypeptidase activity. 1050 34

Recombinant full-length human procathepsin F, produced in the baculovirus expression system, was partially processed during the purification procedure to a form lacking the N-terminal cystatin-like domain and activated with pepsin. Active cathepsin F efficiently hydrolyzed Z-FR-MCA (kcat/Km=106 mM(-1) s(-1)) and Bz-FVR-MCA (kcat/Km=8 mM(-1) s(-1)), whereas hydrolysis of Z-RR-MCA was very slow (kcat/Km<0.2 mM(-1) s(-1)). Cathepsin F was rapidly and tightly inhibited by cystatin C, chicken cystatin and equistatin with Ki values in the subnanomolar range (0.03-0.47 nM), whereas L-kininogen was a less strong inhibitor of the enzyme (Ki=4.7 nM). Stefin A inhibited cathepsin F slowly (kass=1.6 x 10(5) M(-1) s(-1)) and with a lower affinity (Ki=25 nM). These data suggest that cathepsin F differs from other related endopeptidases by considerably weaker inhibition by stefins.
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PMID:Human cathepsin F: expression in baculovirus system, characterization and inhibition by protein inhibitors. 1525 82