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)

A mathematical treatment for the general case of enzyme inactivation by an inhibitor that breaks down in solution in a first-order reaction is presented. Cathepsin D was inactivated by fluorescein isothiocyanate with a K(i) of 4.47mum. Kinetic constants were also determined for the inactivation of cathepsin D by 1,1-bis(diazoacetyl)-2-phenylethane, and the inactivation of pepsin C by diazoacetyl-dl-norleucine methyl ester.
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PMID:Kinetics of irreversible enzyme inhibition by an unstable inhibitor. 461 85

The relative contents of gastricsinogen, the inactive zymogen precursor of gastric gastricsin (EC 3.4.23.3), and cathepsin D (EC 3.4.23.5) in normal and benign hyperplasia of the prostate gland have been determined. Gastricsinogen levels are significantly lower (0.116 +/- 0.02 U/gm. wet tissue) in the hyperplastic than in normal prostates (0.65 +/- 0.06 U/gm.). Conversely, cathepsin D levels are higher in the diseased (0.705 +/- 0.17 U/gm.) as opposed to normal prostatic tissue (0.39 +/- 0.12 U/gm.). The average gastricsin-cathepsin D differences between the 2 tissues (0.26 +/- 0.025 for normal prostates and -0.59 +/- 0.057 SEM for hyperplastic tissue) are also significantly different (p less than 0.001). It is suggested that the simple determination of these 2 acid proteinases in prostate homogenates could be used as alternative and complementary marker enzymes for the study of the physiopathologic status of the prostate gland.
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PMID:Gastricsin and cathepsin D in normal and hypertrophic human prostates. 617 74

Procathepsin D-II (Mr = 37 500) was purified from Japanese monkey lung at pH 7.0, and was shown to be converted to the active form, cathepsin D-II (Mr = 33 000) via an intermediate (Mr = 35 500) upon treatment at pH 3.0 and 14 degrees C. Procathepsin D-II was shown to be the inactive precursor of cathepsin D-II based on the following results: the former was inactive toward heat-denaturated casein at pH 5.4 whereas the latter was active; the former was not inactivated by diazoacetyl-DL-norleucine methyl ester in the presence of Cu2+ ion at pH 6.0 whereas the latter was inactivated rapidly under the same conditions; and the former had no affinity to pepstatin-Sepharose between pH 5 and 7 whereas the latter was adsorbed to it. With a rabbit antiserum against procathepsin D-II, cathepsin D-II, pepsinogen C and pepsin C of Japanese monkey were each found to give a single precipitin line which fused completely with each other on agarose plate. On the other hand, cathepsin D-I purified from the monkey lung, and pepsinogens A (I, II, III-1, III-2 and III-3) obtained from the monkey gastric mucosa failed to precipitate with the antiserum. With the antiserum against the monkey pepsinogen C, the same results were obtained. Further, procathepsin D-II and pepsinogen C were shown to have the same amino-terminal amino acid sequence, Ala-Val-Val-Lys-Val-Pro-Leu-Lys-Lys-Phe-Lys-. All these results indicate a strong similarity of procathepsin D-II and cathepsin D-II to pepsinogen C and pepsin C, respectively.
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PMID:Identification of monkey lung procathepsin D-II as a pepsinogen-C-like acid protease zymogen. 640 25

Val-D-Leu-Pro-Phe-Phe-Val-D-Leu, a specific inhibitor of aspartate proteinases of the pepsin type, was synthesized. Its bonding to activated 6-aminohexanoic acid-Sepharose 4B afforded an affinity support suitable for the purification of human, porcine, and chicken pepsin, human gastricsin, and bovine cathepsin D. These enzymes bind to the support over the pH range 2-5 at 0-1.5 M concentration of NaCl. A buffer at pH greater than or equal to 6, low ionic strength, and containing 20% dioxane can serve as a general desorption agent. The proteinases were isolated from the crude extracts by a single-step procedure in a high degree of purity and in yields exceeding 70%; human pepsin, however, was not separated from human gastricsin. The support does not show any binding capacity for rat plasma renin at pH 7.4 and for some cysteine endopeptidases (cathepsin B, H, and L) at pH 3-5. The cathepsin D preparations isolated by affinity chromatography on the new support and on pepstatin-Sepharose were of the same degree of purity as evidenced by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, N-terminal amino acid sequences, and specific activity.
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PMID:Purification of pepsins and cathepsin D by affinity chromatography on Sepharose 4B with an immobilized synthetic inhibitor. 643 40

Aspartic proteinases are produced in the human body by a variety of cells. Some of these proteins, examples of which are pepsin, gastricsin, and renin, are secreted and exert their effects in the extracellular spaces. Cathepsin D and cathepsin E on the other hand are intracellular enzymes. The least characterized of the human aspartic proteinases is cathepsin E. Presented here are results of studies designed to characterize the binding specificities in the active site of human cathepsin E with comparison to other mechanistically similar enzymes. A peptide series based on Lys-Pro-Ala-Lys-Phe*Nph-Arg-Leu was generated to elucidate the specificity in the individual binding pockets with systematic substitutions in the P5-P2, and P2'-P3' based on charge, hydrophobicity, and hydrogen bonding. Also, to explore the S2 binding preferences, a second series of peptides based on Lys-Pro-Ile-Glu-Phe*Nph-Arg-Leu was generated with systematic replacements in the P2 position. Kinetic parameters were determined for both sets of peptides. The results were correlated to a rule-based structural model of human cathepsin E, constructed on the known three-dimensional structures of several highly homologous aspartic proteinases; porcine pepsin, bovine chymosin, yeast proteinase A, human cathepsin D, and mouse and human renin. Important specificity-determining interactions were found in the S3 (Glu-13) and S2 (Thr-222, Gln-287, Leu-289, Ile-300) subsites.
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PMID:Exploring the binding preferences/specificity in the active site of human cathepsin E. 756 64

CGP 53437 is a peptidomimetic inhibitor of human immunodeficiency virus type 1 (HIV-1) protease containing a hydroxyethylene isostere. The compound inhibited recombinant HIV-1 protease with a Ki of 0.2 nM. The inhibition constant versus human cathepsin D and human cathepsin E was 4 nM. Human pepsin and gastricsin were inhibited with Kis of 8 and 500 nM, respectively, and human renin was inhibited with a Ki of 190 microM. The replication of HIV-1/LAV, HIV-1/Z-84, and HIV-1/pLAI was inhibited with a 90% effective dose of 0.1 microM in acutely infected MT-2 cells. The 50% cytotoxic dose was 100 microM. Similar antiviral activity was observed when the compound was added up to 10 h after infection. At the effective concentration, processing of Gag precursor protein p55 was greatly reduced, confirming an action on the late stage of the virus life cycle, as expected. The efficacy of the inhibitor was also demonstrated by using primary human peripheral blood lymphocytes infected with the HIV-1/LAV strain, low-passage clinical isolates obtained from HIV-1-seropositive individuals (including a zidovudine-resistant strain), and HIV-2/ROD. In these cells, CGP 53437 delayed the onset of HIV replication in a dose-dependent fashion (substantial effects with concentrations of > or = 0.1 microM) as long as the inhibitor was maintained in the culture. CGP 53437 was orally bioavailable in mice. Concentrations in plasma 10-fold in excess of the in vitro antiviral 90% effective dose could be sustained for several hours after oral application of 120 mg/kg. Therefore, CGP 53437 has the potential to be a therapeutically useful anti-HIV agent for the treatment of AIDS.
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PMID:CGP 53437, an orally bioavailable inhibitor of human immunodeficiency virus type 1 protease with potent antiviral activity. 825 28

Via a combination of chemical and enzymatic synthesis, new hexapeptide substrates convenient for use in activity assessment of several aspartyl proteinases--porcine pepsin, human pepsin, gastricsin, and cathepsin D--were prepared. These peptide derivatives, o-aminobenzoyl-Ala-Ala-Phe-Phe-Ala-Ala-p-nitroanilide and N-(o-aminobenzoyl-Ala-Ala-Phe-Phe-Ala-Ala)-N'-2,4-dinitrophenyl ethylenediamine, contain a fluorescent o-aminobenzoyl moiety as well as p-nitroaniline or N-2,4-dinitrophenyl ethylenediamine--the groups that cause fluorescence quenching. Aspartyl proteinases hydrolyze the Phe-Phe peptide bond in the substrates, which diminishes quenching due to separation of the fluorescent and quenching moieties and leads to an increase in the fluorescence intensity of o-aminobenzoyl residue. Abz-Ala-Ala-Phe-Phe-Ala-Ala-Ded, being fairly well hydrolyzed by HIV proteinase, might be used for assay of this enzyme.
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PMID:Fluorogenic peptide substrates for assay of aspartyl proteinases. 871 88

The HIV protease (or proteinase) enzyme is an essential component of the replicative cycle of HIV, performing the post-transitional processing of the gag and gag-pol gene products into the functional core proteins and viral enzymes. Inhibition of this enzyme leads to production of immature noninfectious viral progeny, and hence prevention of further rounds of infection. Structurally, the enzyme is a homodimer consisting of two identical 99 amino acid chains. HIV protease is a member of the aspartic protease family but is structurally dissimilar to human aspartic proteases such as renin, gastricsin and cathepsin D and E, suggesting the possibility of creating inhibitors with a wide therapeutic index. At least 6 inhibitors of HIV protease are currently in clinical development: saquinavir, indinavir, ritonavir, nelfinavir (AG-1343), KNI-272 and VX-478, the first four of which have shown antiretroviral activity and acceptable tolerability in initial phase I/II clinical trials. Resistance or reduced sensitivity to the leading protease inhibitors has been reported in vivo and appears to be associated with loss of therapeutic effect. However, resistance patterns appear to be distinct. Treatment for 1 year with indinavir has been reported to lead to selection of virus in 4 patients, which was cross-resistant to all other leading protease inhibitors. On the other hand, a larger series of clinical isolates from patients receiving saquinavir alone or in combination with zidovudine for up to 3 years did not lead to virus cross-resistant to either indinavir or ritonavir. This suggests that care should be exercised in designing the sequence of protease usage. Additionally, differing resistance patterns may be used to select combinations of protease inhibitors in future trials. Data from studies combining protease inhibitors with nucleoside analogues suggest value in terms of larger and more prolonged virological and immunological marker responses than are observed with single agent therapy, and this is likely to be the primary role for protease inhibitors; both in initial combinations for patients commencing therapy and as add-in therapies for patients previously treated with antiretrovirals. However, in vitro and animal pharmacokinetic studies also give evidence of the possibility of combining protease inhibitors, potentially leading to improved bioavailability, antiviral synergy and delay in emergence of viral resistance.
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PMID:Current knowledge and future prospects for the use of HIV protease inhibitors. 886 42

Molecular cloning of a cDNA for a pepsin inhibitor in the round worm, Ascaris suum, was achieved. The ORF was found to encode a 20-residue potential signal peptide and a 149-residue inhibitor moiety. Northern analysis showed the mRNA for the inhibitor to be expressed in the body wall and not in the viscera. To obtain the active inhibitor, we constructed a yeast expression vector, pYES2API, containing the inducible galactosidase promoter and a DNA fragment encoding a fusion protein of the yeast alpha-factor leader and the Ascaris pepsin inhibitor. The active inhibitor was secreted in the culture medium, the yield being approximately 3 mg x l(-1) x day(-1), and purified by a two-step procedure that included HPLC. The inhibitor inactivated pepsin A and cathepsin E almost completely at amounts equimolar with the enzymes, but was 100-fold less effective against pepsin C and did not act on cathepsin D and renin. Ki values for the inhibition of pepsin A and cathepsin E were in the nanomolar range below pH 5. Since the inhibitor activity was lost by modification of specific Lys residues, including Lys110, an electrostatic interaction between these Lys residues and Asp/Glu residues of pepsin A or cathepsin E was thought to be essential for the inhibition.
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PMID:Molecular cloning, expression and characterization of an Ascaris inhibitor for pepsin and cathepsin E. 965 82

A series of fluorogenic tetra-, penta-, and hexapeptide substrates of the general structure Abz-X-Phe-Phe-Y-Ded (or -pNa in place of -Ded), where X = Ala, Ala-Ala, or Val-Ala and Y = -, Ala, or Ala-Ala, were proposed. Kinetic parameters of hydrolysis of these substrates by pepsin, cathepsin D, human gastricsin, pig pepsin, calf chymosin, and aspergillopepsin A were determined. The compounds synthesized proved to be effective substrates for aspartyl proteases of diverse origins.
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PMID:[A study of aspartyl proteases using intramolecularly quenched fluorogenic peptide substrates]. 1081 17


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