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 protease activity in guts of Ornithodoros tholozani females was studied in vitro. The intracellular protease in Ornithodoros tholozani guts has a pH optimum of about 3.0. Hemoglobin is the preferred substrate, and bovine serum albumin is digested very slowly. In this respect the protease resembles cathepsin D. Unfed ticks contain a small amount of protease in the gut. After feeding the level of protease increases gradually for several days until peak protease activity is attained. The level of gut protease activity depends on the size of the blood meal taken and on the interval after feeding. After a period of peak protease activity, the level of protease declines. The level of gut protease in unmated females (kept at 27 degrees C) did not reach prefeeding levels within 100 days. The level of gut proteolytic activity, as determined by in vitro protease assays, does not reflect the degree of blood digestion which takes place in vivo. After a period of rapid digestion, lasting for about two weeks, the undigested part of the blood meal remains unchanged in the lumen of the gut. At that time the gut tissue contains considerable levels of protease, which can be demonstrated by in vitro assays. Presumably, the protease remains active inside the gut cells, although the uptake of hemoglobin from the gut lumen has ceased. The results are compared to those obtained in other tick species.
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PMID:Protease activity in female Ornithodoros tholozani ticks. 1 32

In a continuing study of the physiological role of protein breakdown in the hypothalamus, acid proteinase from bovine hypothalamus was purified about 1000-fold. The molecular weight of the enzyme was approximately 50,000. Masimal activity against hemoglobin was obtained at pH 3.2-3.5; serum albumin was split much more slowly. Hypothalamus acid proteinase was partially inhibited by beta-phenyl pyruvate, or benzethonium Cl, and was completely inhibited by low concentrations of pepstatin. This proteinase splits somatostatin, substance P, and analogs of substance P. The probable sites of enzyme action on these peptides were determined by the end group dansyl technique. The enzyme, most likely cathepsin D, may play an important role in the formation and breakdown of peptide hormones in the hypothalamus.
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PMID:Acid proteinase of hypothalamus. Purification, some properties, and action on somatostatin and substance P. 2 91

A unique acid proteinase different from cathepsin D was purified from rat spleen by a method involving precipitation at pH 3.5, affinity chromatography on pepstatin-Sepharose 4B and concanavalin A-Sepharose 4B, chromatography on Sephadex G-100 and DEAE-Sephacel, and isoelectric focusing. A purification of 4200-fold over the homogenate was achieved and the yield was 11%. The purified enzyme appeared to be homogeneous on electrophoresis in polyacrylamide gels. The isoelectric point of the enzyme was determined to be 4.1-4.4. The enzyme hydrolyzed hemoglobin with a pH optimum of about 3.1. The molecular weight of the enzyme was estimated to be about 90000 by gel filtration on Sephadex G-100. In sodium dodecylsulfate polyacrylamide gel electrophoresis, the purified enzyme showed a single protein band corresponding to a molecular weight of about 45000. The hydrolysis of bovine hemoglobin by the enzyme was much higher than that of serum albumin. Various synthetic and natural inhibitors of the enzyme were tested. The enzyme was inhbited by Zn2+, Fe3+, Pb2+, cyanide, p-chloromercuribenzoate, iodoacetic acid and pepstatin, whereas 2-mercaptoethanol, phenylmethyl-sulfonyl fluoride and leupeptin showed no effect.
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PMID:Affinity purification and properties of cathepsin-E-like acid proteinase from rat spleen. 3 48

Acid and neutral proteinases were isolated with the purpose of investigating their participation in the breakdown of hypothalamic peptides and proteins. The acid proteinase was purified about 1000-fold from hypothalamus by precipitation with acetone, chromatography on SP-Sephadex G-50, gel filtration through column of G-100 and chromatography on DEAE-Sephadex A-50. The molecular weight of the enzyme was approximately 50.000. Maximal activity against hemoglobin was obtained at pH 3,2--3,5: serum albumin was split much more slowly. Hypothalamus acid proteinase was partially inhibited by beta-phenyl pyruvate, benzothonium cloride, and was completely inhibited by low concentrations of pepstatin. This proteinase splits somatostatin, Substance P and some C-fragments of Substance P. The probable sites of enzyme action on these peptides were determined by the end group dansyl technique. Neutral proteinase was isolated from the supernatant fraction(100.000 g) of a 0,3 M sucrose homogenate of bovine hypothalamus by chromatography on DEAE Sephadex A-50, gel filtration through Sephadex G-100 and rechromatography on DEAE sephadex A-50 using luliberin as substrate. The rates of breakdown of luliberin and denaturated hemoglobin were measured by fluorometric estimation of acid-soluble peptides wieht o-phthaldialdehyde. The purifed enzyme preparations have a pH optimum of activity at 7--7,5. The enzymes molecular weight was approximatelyy 30--40.000. Enzyme activity was inhibited by L-1-tosylamide-2-phenylethylchloromethyl ketone, p-chloromercuribenzoate and divalent ions Co2+, Zn2+ and was significantly enhanced by dithiothreitol. The Km values for the reaction of hydrolysis of luliberin and hemoglobin were 1,33.10(-5) and 5,2.10(-5) M respectively. The neutral proteinase from the hypothalamus cleaves luliberin, somatostatin and Substance P. Sites of action of the enzyme upon those peptides were determined by means of the dansyl technique. The acid proteinase, most likely cathepsin D, and neutral proteinase from hypothalamus, may play an important role in the formation and breakdown of peptide hormones in the hypothalamus.
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PMID:[Breakdown of luliberin, somatostatin and substance P as an effect of hypothalamic endopeptidases]. 4 63

Canine liver lysosomes were purified by sucrose discontinuous density gradient centrifugation and then ruptured by sonication to obtain the soluble fraction. This soluble lysosomal fraction, which contained a 25-fold increase in acid phosphatase activity per mg of total protein when compared with the original homogenate, was incubated with a subfraction (1.110 less than d less than 1.210 g/cm3, HDL3) of canine high density lipoproteins (HDL) at pH 3.8. HDL3 proteolysis by lysosomal proteases, measured as the release of peptides and amino acids by the ninhydrin reaction, followed hyperbolic curves with straight lines (r = 0.99) obtained on Lineweaver-Burk plots. Km calculated from the Lineweaver-Burk plot was 635 mug of HDL3 protein per 0.5 ml of incubation mixture. Optimum HDL3 proteolysis was observed from pH 3.8 to 4.5. Incubation with the other subcellular organelle fractions did not result in HDL3 proteolysis. To evaluate the effects of enzyme inhibitors, iodoacetate, p-chloromercuribenzoate (both specific for the endopeptidase, cathepsin B (EC 3.4.22.1)) and pepstatin (specific for the endopeptidase, cathepsin D (EC 3.4.23.5) were tested. Iodoacetate and p-chloromercuribenzoate inhibited HDL3 proteolysis 100% and bovine serum albumin proteolysis 65%. Pepstatin inhibited HDL3 proteolysis 45% and bovine serum albumin proteolysis 70%. The in vitro data presented support the hypothesis that hepatic lysosomes play an important role in HDL3 catabolism in the dog. Furthermore, results obtained from enzyme inhibition studies suggest that a specific lysosomal endopeptidase, cathepsin B, may play the key role in HDL3 proteolysis.
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PMID:Proteolysis of canine apolipoprotein by acid proteases in canine liver lysosomes. 17 45

The purity of cathepsin D has been increased from 150 units/mg to over 200 units/mg. Peptides such as Ala-Phe-NH2, His-Phe-NH2 and Phe-Phe were split by impure enzyme and activity was blocked by pepstatin and diazoacetylnorleucine methyl ester. Pure preparations no longer digested these peptides. This points to the presence of a second peptidase activity similar to cathepsin D in specificity and inhibition properties, but distinct from it . Cathepsin D splits the peptides Leu-Phe-NH2, Leu-Tyr-NH2, Ac-Phe-TyrI2, and Ala-Leu-Tyr-Leu upon overnight incubation. More rapid splitting is found with phenyl sulfite, Glu-Ala-Leu-Tyr-Leu-Val, and Bz-Arg-Gly-Phe-Phe-Leu-4-methoxy-beta-naphthylamide. Digestion of bovine hemoglobin and human serum albumin by ruptured rat liver tritosomes was studied over the pH range 2.5-6.5. The combined action of cathepsin D and thiol proteinases accounted for most of the digestion. Cathepsin D accounted for 75% of the hemoglobin digestion at pH 3 and 45% at pH 5. Thiol proteinase accounted for 85% of the albumin digestion at pH 5. The role of cathepsin D in the development of embryonic limbs and skin, in uterine involution, and in cartilage degradation was reviewed. The activity of cathepsin D on cartilage matrix proteoglycans is limited to acid pH values. Human articular cartilage also contains metalloproteases active at pH 4.5 and 5.7.
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PMID:Specificity and biological role of cathepsin D. 59 4

Cathespin D from the retinal pigment epithelium of bovine eyes was purified about 25-fold from a crude extract of retinal pigment epithelium by acid treatment, ammonium sulfate fractionation, and Sephadex G-200 column chromatography. The purified enzyme hydrolyzed bovine serum albumin optimally at pH values close to 4.0. Exposure of the enzyme to 60 degrees C. for 2 minutes resulted in 50 per cent inactivation of the activity. The enzyme activity was completely inhibited by 0.1 microgram per milliliter of pepstatin, slightly inhibited by trasylol, and not affected by soybean trypsin inhibitor. The apparent molecular weight of cathepsin D was estimated to be about 60,000 by gel filtration on Sephadex G-200.
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PMID:Partial purification and properties of cathepsin D in the retinal pigment epithelium. 108 Jan 46

Two unique cathepsin D-type proteases apparently present only in rat thoracic duct lymphocytes and in rat lymphoid tissues are described. One, termed H enzyme, has an apparent molecular weight of similar to95,000; the other, termed L enzyme, has an apparent molecular weight of similar to45,000, in common with that of most cathepsins D from other tissues and species. Both enzymes differ from cathepsin D, however, by a considerably greater sensitivity to inhibition by pepstatin and by a smaller degree of inhibition by an antiserum which inhibits rat liver cathepsin D. H enzyme is converted to L enzyme by treatment with beta-mercaptoethanol; the relationship between the two enzymes remains unknown. H and L enzyme have been detected in rat lymphoid tissues and in mouse spleen, but they are not present in other rat tissues (liver, kidney, adrenals), rabbit tissues, calf thymus, bovine spleen, or human tonsils. As measured on acid-denatured bovine hemoglobin as substrate, both enzymes have pH activity curves identical with that of rat liver cathepsin D, with optimal activity at pH 3.6. Activity on human serum albumin is much less and also shows an optimum at pH 3.6; hence, neither enzyme has the properties of cathepsin E. Thiol-reactive inhibitiors have no effect on the activity of H and L enzyme; thus they do not belong to the B group of cathepsins. Additional information, discussed in this paper, leads us to conclude that partially purified H and L enzymes are cathepsin D-type proteases.
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PMID:Unique cathepsin D-type proteases in rat thoracic duct lymphocytes and in rat lymphoid tissues. 114 Dec 27

1. 'Inhibitor fragment' isolated from human serum albumin degraded by rabbit cathepsin D is composed of one peptide chain with two intrachain disulphide bonds. There are two kinds of inhibitor molecules having different N-terminal amino acids: one is threonine and the other glutamine. 2. Fragment F1, isolated from inhibitor degraded by trypsin, is composed of two chains linked by a disulphide bond. There are three kinds of fragment F1. All have one alpha chain in common, which has an intrachain disulphide bond. They differ by the nature of the chain, which is linked to the alpha chain by a disulphide bond. The epsilon chain is present in trace amounts. The two other chains, beta and gamma, differ by their C-terminal amino acid, which is respectively arginine and lysine. 3. Inhibitor is composed of the last 92 or 89 residues of the human albumin molecule and fragment F1 is composed of two parts of this C-terminal portion of the albumin molecule.
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PMID:Chemical structure of two fragments of human serum albumin and their location in the albumin molecule. 116 60

The degradation of proteins of the rod outer segment (ROS) fraction by partially purified cathepsin D [EC 3.4.23.5] from the retinal pigment epithelium was studied. The ROS fraction, prepared from bovine eyes by sucrose density gradient centrifugation, had little cathepsin D activity. Partially purified cathepsin D, obtained from crude extract of bovine retinal pigment epithelium using bovine serum albumin as a substrate, hydrolyzed the porteine of the ROS fraction. The rate of degradation of ROS proteins was proportional to both the enzyme concentration and the incubation time. With ROS proteins as substrate, the optimal pH of cathepsin D was about 3.5. The degradation of ROS proteins was inhibited by pepstatin.
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PMID:Degradation of rod outer segment proteins by cathepsin D. 122 25


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