Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.23.5 (cathepsin D)
4,130 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The formation of inactive complexes in excess molar amounts of human cathepsins H and L with their protein inhibitors human stefin A, human stefin B and chicken cystatin at pH 5.6 has been shown by measurement of enzyme activity coupled with reverse-phase HPLC not to involve covalent cleavage of the inhibitors. Inhibition must be the direct result of binding. On the contrary the interaction of cystatins with aspartic proteinase cathepsin D at pH 3.5 for 60 min followed by HPLC resulted in their inactivation accompanied by peptide bond cleavage at several sites, preferentially those involving hydrophobic amino acid residues. The released peptides do not inhibit papain and cathepsin L. These results explain reported elevated levels of cysteine proteinases and lead to the proposal that cathepsin D exerts an important function, through inactivation of cystatins, in the increased activities of cysteine proteinases in human diseases including muscular distrophy.
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PMID:Cathepsin D inactivates cysteine proteinase inhibitors, cystatins. 326 Nov 70

Activities of several proteinase-like peptidases have been determined in homogenates of malignant tissue, non-malignant tissue adjacent to the tumour (A-NM) and non-malignant tissue distant to the tumour (D-NM) from 17 patients undergoing surgery for histologically confirmed gastric malignancies. In homogenates of malignant tissues the activities of collagenase, cathepsin B, cathepsin (B+L), cathepsin H and cathepsin D were significantly higher than in D-NM tissues. By contrast, the levels of plasminogen activator were significantly lower in malignant tissues than in the D-NM tissues. Furthermore, the activities of collagenase-like and the cysteine-proteinase-like peptidases in the A-NM tissues were lower than in malignant tissues but higher than in the D-NM tissues. Separation of full-thickness non-malignant tissues into mucosal and seromuscular layers revealed significantly higher activities in the former. The elevated levels of these proteinase-like peptidases in homogenates of gastric cancer tissue suggests an important role for these enzymes in tumour invasion.
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PMID:Proteinase-like peptidase activities in malignant and non-malignant gastric tissue. 388 38

Rabbit cardiac cathepsin D is initially synthesized as an inactive, apparent molecular weight (Mr) 53,000, pI 6.6 precursor (procathepsin D) that is proteolytically processed during intracellular transport to produce the Mr 48,000 isoforms of active cathepsin D found in cardiac lysosomes. To examine potential proteases responsible for intracellular proteolytic processing, biosynthetically labeled procathepsin D was isolated from rabbit ventricular tissue perfused for 30 min with [35S]methionine. Procathepsin D was then incubated in vitro (40 degrees C, 1-240 min) with active cathepsin D, papain, and cathepsin B, either singly or sequentially, and the reaction products analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and two-dimensional electrophoresis. Incubation of 35S-labeled procathepsin D with active cathepsin D produced a single reaction product (Mr 51,000; pI 6.2). This limited proteolysis occurred at pH 3-5 and was inhibited by pepstatin. Incubation of 35S-labeled procathepsin D with papain or cathepsin B produced a major reaction product (Mr 48,000; pI 6.4) and a minor form (Mr 50,000; pI 6.0). These reactions occurred at pH 4-7 and were inhibited by leupeptin but not pepstatin. Only the Mr 48,000, pI 6.4 products of papain and cathepsin B-mediated proteolysis comigrated with the most basic isoform of active cathepsin D found in cardiac tissue. In addition, the Mr 51,000 intermediate produced by cathepsin D was susceptible to further limited proteolysis by cysteine proteases with resultant production of a Mr 48,000 product. Thus the intracellular proteolytic processing of rabbit cardiac procathepsin D does not result solely from autocatalysis but requires at least one other protease, possibly cathepsin B.
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PMID:Limited proteolysis of rabbit cardiac procathepsin D in a cell-free system. 396 72

The proteolytic maturation of cathepsin D polypeptides was studied in lysosomes isolated from metabolically labeled fibroblasts. In lysosomes isolated from fibroblasts labeled with [35S]methionine, 70-95% of labeled cathepsin D polypeptides were represented by a Mr = 47,000 polypeptide after a 20-min pulse and 75-min chase. When these lysosomes were incubated in vitro, up to 70% of the Mr = 47,000 polypeptide was processed to mature cathepsin D polypeptides. The processing was dependent on the integrity of the lysosomes, had an optimum between pH 6 and 7, and could be stimulated by dithiothreitol and ATP. The noncleavable ATP analogue, adenosine 5'-(beta, gamma-imido)triphosphate, and GTP, CTP, and UTP could not substitute for ATP. The ATP-dependent stimulation was associated with an acidification of lysosomes. It was inhibited by agents that dissipate the lysosomal pH gradient (carbonyl cyanide p-trifluoromethoxyphenylhydrazone, N,N'-dicyclohexylcarbodiimide, nigericin, NH4Cl). A stimulatory effect of ATP was observed also at pH 5.5. The stimulation at pH 5.5 was not associated with acidification of lysosomes and was resistant to protonophores. Inhibitors of lysosomal cysteine proteinases and N-ethylmaleimide inhibited the processing. In the presence of ATP the processing activity was partially protected from inhibition by N-ethylmaleimide. In conclusion, the maturation of cathepsin D in lysosomes depends on cysteine proteinases and is stimulated by the ATP-driven acidification of lysosomes. In addition, ATP stimulates maturation at pH 5.5 by a mechanism not involving the proton pump.
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PMID:Processing of human cathepsin D in lysosomes in vitro. 397 22

The effects of two proteinase inhibitors, leupeptin and pepstatin on the development of 9.5-day rat conceptuses in vitro has been studied. All cultures were of 48 h duration and the inhibitors were present throughout the entire period. When pepstatin was added to the culture medium (5-25 micrograms/ml) conceptuses developed and grew to an extent that did not differ from untreated controls. However, leupeptin (1-4 micrograms/ml) caused severe growth retardation and abnormal development of conceptuses. The effects of the two inhibitors on the hydrolysis of 125I-labelled BSA and haemoglobin by homogenates of 10.5-day yolk sac indicated the biochemical basis for the differential toxic effects of the two inhibitors on development. Leupeptin was highly inhibitory of the degration of both substrates whereas pepstatin caused no inhibition of 125I-labelled BSA hydrolysis, and only a slight inhibition of haemoglobin hydrolysis. These observations demonstrate that cathepsin D, a lysosomal aspartic proteinase that is specifically inhibited by pepstatin is not involved in yolk-sac-mediated protein utilization by early organogenesis-phase conceptuses and that lysosomal cysteine proteinases, specifically inhibited by leupeptin, are of paramount importance in this yolk sac function.
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PMID:Comparative effects of cathepsin inhibitors on rat embryonic development in vitro. Evidence that cathepsin D is unimportant in the proteolytic function of yolk sac. 403 44

1. Experiments were made to determine whether the purified lysosomal proteinases, cathepsins B1 and D, degrade acid-soluble collagen in solution, reconstituted collagen fibrils, insoluble collagen or gelatin. 2. At acid pH values cathepsin B1 released (14)C-labelled peptides from collagen fibrils reconstituted at neutral pH from soluble collagen. The purified enzyme required activation by cysteine and EDTA and was inhibited by 4-chloromercuribenzoate, by the chloromethyl ketones derived from tosyl-lysine and acetyltetra-alanine and by human alpha(2)-macroglobulin. 3. Cathepsin B1 degraded collagen in solution, the pH optimum being pH4.5-5.0. The initial action was cleavage of the non-helical region containing the cross-link; this was seen as a decrease in viscosity with no change in optical rotation. The enzyme also attacked the helical region of collagen by a mechanism different from that of mammalian neutral collagenase. No discrete intermediate products of a specific size were observed in segment-long-spacing crystalloids (measured as native collagen molecules aligned with N-termini together along the long axis) or as separate peaks on gel filtration chromatography. This suggests that once an alpha-chain was attacked it was rapidly degraded to low-molecular-weight peptides. 4. Cathepsin B1 degraded insoluble collagen with a pH optimum below 4; this value is lower than that found for the soluble substrate, and a possible explanation is given. 5. The lysosomal carboxyl proteinase, cathepsin D, had no action on collagen or gelatin at pH3.0. Neither cathepsin B1 nor D cleaved Pz-Pro-Leu-Gly-Pro-d-Arg. 6. Cathepsin B1 activity was shown to be essential for the degradation of collagen by lysosomal extracts. 7. Cathepsin B1 may provide an alternative route for collagen breakdown in physiological and pathological situations.
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PMID:Cathepsin B1. A lysosomal enzyme that degrades native collagen. 420 88

Proteolytic enzymes have been studied in extracts of human articular cartilage by the use of micromethods. The digestion of hemoglobin at pH 3.2 and of cartilage proteoglycan at pH 5 was shown to be due chiefly to cathepsin D. Cathepsin D was purified 900-fold from human patellar cartilage. Its identity was established by its specific cleavage of the B chain of insulin. At least six multiple forms of cathepsin D are present in cartilage; these corresponded to bovine forms 4-9. Cathepsin D had no action on proteins at pH 7.4. However, cartilage extracts digested proteoglycan, casein, and histone at this pH. The proteolytic activities against these three substrates were purified about 170-, 160-, and 70-fold, respectively. Each activity appeared in multiple forms on DEAE-Sephadex chromatography. The three activities appear to be different since cysteine inhibited casein digestion, aurothiomalate inhibited histone digestion, and neither inhibited proteoglycan digestion. Tests with a wide range of inhibitors and activators suggest that these three activities differ from other neutral proteases described in the literature.
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PMID:Neutral proteases and cathepsin D in human articular cartilage. 427 25

1. An enzyme present in rat liver extracts degraded insoluble collagen maximally at pH3.5. Collagenolytic activity was more abundant in kidney, spleen and bone marrow and was also present in decreasing concentrations in ileum, lung, heart, skin and muscle. 2. The crude collagenolytic cathepsin was activated by cysteine and dithiothreitol, but not by 2-mercaptoethanol. Iodoacetamide, p-chloromercuribenzoate and 7-amino-1-chloro-3-l-tosylamidoheptan-2-one hydrochloride inhibited the enzyme. Zn(2+), Fe(3+) and Hg(2+) ions were strongly inhibitory, but Ca(2+), Co(2+), Mg(2+) and Fe(2+) ions had little or no effect. EDTA was an activator of the enzyme. Inhibitors of cathepsin B were found to enhance collagenolysis, but phenylpyruvic acid, a cathepsin D inhibitor, inhibited the enzyme. Di-isopropyl phosphorofluoridate had no effect. 3. Collagenolysis at pH3.5 and 28 degrees C was restricted to cleavage of the telopeptide region in insoluble collagen, and the material that was solubilized consisted mostly of alpha-chains. 4. The collagenolytic cathepsin was separated from cathepsins B2 and D by fractionation on Sephadex G-100 and a partial separation from cathepsin B1 was obtained by chromatography on DEAE-Sephadex. 5. The function of the collagenolytic cathepsin in the catabolism of collagen is discussed in relation to the action of the other lysosomal proteinases and the neutral collagenase.
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PMID:The nature of the collagenolytic cathepsin of rat liver and its distribution in other rat tissues. 465 Nov 35

Cathepsin H was purified from human liver by a method involving autolysis and acetone fractionation, and chromatography on DEAE-cellulose, Ultrogel AcA 54, hydroxyapatite and concanavalin A-Sepharose. The procedure allowed for the simultaneous isolation of cathepsin B and cathepsin D. Cathepsin H was shown to consist of a single polypeptide chain of 28 000 mol.wt., and affinity for concanavalin A-Sepharose indicated that it was a glycoprotein. The enzyme existed in multiple isoelectric forms, the two major forms having pI values of 6.0 and 6.4; it hydrolysed azocasein (pH optimum 5.5), benzoylarginine 2-naphthylamide (Ba-Arg-NNap), leucyl 2-naphthylamide (Arg-NNap), (pH optimum 6.8). Arg-NNap and Arg-NMec, unlike Bz-Arg-NNap-, were not hydrolysed by human cathepsin B. Cathepsin H was similar to cathepsin B in being irreversibly inactivated by exposure to alkaline pH. Sensitivity to chemical inhibitors by 1 microM-leupeptin, which gave essentially complete inhibition of the other lysosomal cysteine proteinases, cathepsins B and L.
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PMID:Human cathepsin H. 616 52

The proteinase activity of the low molecular weight cytotoxin of Entamoeba histolytica was correlated with its cytotoxicity. Gel-filtered amebal toxin (mol wt 10-30,000) proteinase activities could be assayed on azocasein at pH 6 or on hemoglobin at pH 4.5. Proteinase activity was inhibited by serum fractions, thiol reagents, heavy metals, leupeptin, and antipain. The cytotoxic activity of gel-filtered amebal toxin was inhibited by serum fractions, leupeptin, and antipain. Increased proteinase and cytotoxic activity was produced by treatment with cysteine. These data support the action of a thiol proteinase in the production of cytopathic effects by gel-filtered amebal toxin in vitro. The cytotoxic and proteinase activities were further purified using a combination of column chromatography and preparative isoelectric focusing. Two low molecular weight cytotoxins with proteinase activity on both substrates were isolated. The major cytotoxin had an isoelectric point of 4.5 and a molecular weight of 22,000; the other cytotoxin had a basic isoelectric point. These substances may be cathepsin B-like proteinase and elastase or cathepsin G-like proteinases of E. histolytica. The major proteinase activity in the high molecular weight fraction was not cytotoxic. The isoelectric points of the high molecular weight proteinase activities corresponded to that of mammalian cathepsin D. The major cell rounding cytotoxic activity of E. histolytica extracts in vitro is probably due to the activity of a thiol-containing cathepsin B-like proteinase.
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PMID:Proteinase activities of Entamoeba histolytica cytotoxin. 632 55


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