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 specificity and mode of action of an acid proteinase (EC 3.4.23.6) from Aspergillus saitoi were investigated with oxidized B-chain of insulin, angiotensin II and bradykinin. Further purification of acid proteinase was performed with N,O-dibenzyloxycarbonyl-tyrosine hexamethylene-diamino-Sepharose 4B affinity chromatography and isoelectric focusing. The purified enzyme was free of any other proteolytic activity demonstrated in Asp. saitoi. Acid proteinase from Asp. saitoi hydrolyzed primarily two peptide bonds in the oxidized B-chain of insulin, the Leu(15)-Tyr(16) bond and the Phe(24)-Phe(25) bond. Additional cleavages of the bonds His(10)-Leu(11), Ala(14)-Leu(15) and Tyr(16)-Leu(17) were also noted. Primary splitting sites at Leu(15)-Tyr(16) and Phe(24-)-Phe(25) with acid proteinase from Asp. saitoi were identical with those reported in the work of cathepsin D (EC 3.4.23.5) from human erythrocyte. Hydrolysis of angiotensin II was observed at the Tyr(4)-Ile(5) bond. In conclusion, peptide bonds which have a hydrophobic amino acid such as phenylalanine, tyrosine, leucine and isoleucine in the P'1 position (as defined by Berger and Schechter, [29]) are preferentially cleaved by the trypsinogenactivating acid proteinase from Asp. saitoi.
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PMID:Purification of an acid proteinase from Aspergillus saitoi and determination of peptide bond specificity. 2 99

N-Diazoacetyl-L-phenylalanine 3-phenyl[2,3-3H]propylamide was synthesized and shown to inhibit pepsin A (EC3,4,23.1) and cathepsin D (EC 3.4.23.5) irreversibly and stoicheiometrically in the presence of Cu2+. Quantitative separation of the inhibited enzyme from excess reagent by gel filtration followed by measurement of the radioactivity of the protein peak provided a method for determining the operational molarity of these enzymes. Several other putative active-site-directed irreversible inhibitors were synthesized, but were inactive. Data on the synthesis of these compounds have been deposited as Supplementary Publication SUP50096 (4 pages) at the British Library Lending Division, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1978) 169, 5.
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PMID:A radiochemical titrant for the determination of the operational molarity of solutions of acid proteinases. 4 35

A new protease, detected in an extract of Fasciola hepatica, was isolated and partly purified. The pH optimum for the cleavage of denaturated haemoglobin by the enzyme is pH 3.0. This proteolytic activity is inhibited by diazoacetylnorleucine methyl ester, pepstatin, the pepsin inhibitor from Ascaris suum, and phenylalanine. The cathepsin D inhibitor from potatoes, EDTA, mercaptoethanol and the inorganic salts tested have no inhibitory effect. The cleavage of the B-chain of oxidized insulin by enzyme was studied and compared with the digestion of the same substrate by chicken and pig pepsin. The protease from Fasciola hepatica belongs to the carboxyl group of proteases and probably plays an important role in helminth nutrition.
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PMID:Isolation and some properties of an acid protease from Fasciola hepatica. 4 1

The use of derived and synthetic peptides has contributed greatly to our understanding of encephalitogenic determinants in the basic protein molecule. Peptides derived from BP by use of trypsin, pepsin, cathepsin D (brain and liver) and BNPS-skatole have proven most useful. Synthetic peptides have served to define the disease-inducing determinants with precision. A remarkable feature of these studies is that different antigenic determinants serve as encephalitogenic sites in different species. The encephalitogenic sites comprise short peptide domains of the BP polypeptide chain, only 8 residues (rat), 9 residues (guinea pig), and 10 residues (rabbit) in length. In view of the requirement for both haptenic and carrier specificity of an immunogenic molecule, it is impressive that these peptides themselves elicit the autoimmune disease, EAE. While less active than BP on a molar basis, they are nonetheless potent encephalitogens, producing clinical signs in rats and guinea pigs at less than 1 microgram dose. The data indicate that for most animal species (guinea pig, rat, monkey) there appears to be only one major encephalitogenic determinant, an unusual finding in view of the number of antigenic determinants for cell-mediated immunity existing in the BP molecule. Possibly a combination of genetic and anatomical factors may account for this phenomenon. A relationship may exist between multiple sclerosis and EAE as shown by peptide studies; lymphocytes are found in MS patients during exacerbation sensitized to the same region of BP active in the monkey. The major encephalitogenic sites are: Guinea Pig (9) Phe-Ser-Trp-Gly-Ala-Glu-Gly-Gln-Lys(Arg); Rabbit (10) Thr-Thr-His-Tyr-Gly-Ser-Leu-Pro-Gln-Lys; Rat (8) Ser-Gln-Arg-Ser-Gln-Asp-Glu-Asn; Monkey (14) Phe-Lys-Leu-Gly-Gly-Arg-Asp-Ser-Arg-Ser-Gly-Ser-Pro-Hser.
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PMID:Peptides and autoimmune disease. 8 85

An insoluble preparation of rat liver cathepsin D was obtained by coupling the enzyme to Enzacryl Polyacetal (EPA-cathepsin) and to CNBr-activated Sepharose 4B. EPA-cathepsin was active toward the synthetic hexapeptides (Gly-Phe-Leu)2 and did not split hemoglobin. The optimum pH of splitting was displaced upward by 1.5 units to pH 5.0. The enzyme exhibited maximum activity at 60 degrees C. No appreciable loss of activity was seen on storage of the enzyme for 4 months or after repeated use of the preparations. Coupling of rat liver cathepsin D to activated Sepharose gave preparations active towards both protein and synthetic substrates. The preparations were totally inactive in acid media and exhibited maximum activity at pH 7.0, that is, under physiological conditions. Optimum temperature was 65 degrees. The specific activity of the preparations (pH 7.0, 65 degrees) was 60-110 percent that of the free enzyme in acid media. Proteolytic activity of the Sepharose-coupled cathepsin D was not inhibited by pepstatin, whereas that of the free enzyme was fully inhibited by this reagent. A sarcoma cathepsin, similar in some of its properties to the rat liver enzyme, was also coupled to CNBr-activated Sepharose 4B. The preparation split protein substrates at pH 7.0 and possessed enhanced thermostability. The enzymes fixed on Sepharose showed increased stability.
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PMID:Some properties of cathepsins chemically fixed to carriers. 23 96

A chymotrypsin-like esterase was purified from beef lung. This lysosomal enzyme, not previously characterized, seemed to be composed of two or more forms with molecular weights of about 52 000. It hydrolysed N-benzoyl-DL-phenylalanine beta-naphthol ester at acid and neutral pH; it polymerized L-phenylalanine methyl ester(Phe-OMe) at neutral pH; and it transferred the Phe-residue from Phe-OMe to hydroxylamine at neutral pH. Phenylmethanesulfonyl fluoride, an inhibitor of hydrolytic enzymes with serine in their catalytic site, inhibited this enzyme, but pepstatin, the cathepsin D (EC 3.4.4.23) inhibitor, did not. Sulfhydryl reagents were not required for activity. Macrophages, especially pulmonary alveolar macrophages, were a rich source of this esterase, so it is likely that the enzyme purified from lung came from its macrophages. The esterase hydrolysed and transferred monoamino acid esters, especially those of the aromatic type. Cathepsin C, the dipeptidyl peptide hydrolase (EC 3.4.14.1), acted only on dipeptide esters and amides. Pancreatic chymotrypsin acted on both monoamino acid and dipeptide esters. The chymotrypsin-like esterase did not hydrolyse hemoglobin, casein, or plasma albumin. Thus its proteolytic activity, if present, must be limited to specific substrates, as yet unknown.
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PMID:Macrophage esterase: identification, purification and properties of a chymotrypsin-like esterase from lung that hydrolyses and transfers nonpolar amino acid esters. 24 Apr 26

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

Cathepsin B and cathepsin D were purified from rat liver and skeletal muscle. Electrophoretic analyses revealed that the enzymes were highly purified, and isoelectric focusing demonstrated multiple forms of both enzymes. Purified actin and myosin, as well as actin and myosin in myofilaments and myofibrils, were degraded by the purified cathepsins B and D. Degradation of myosin was completely blocked by the cathepsin B and D inhibitors, leupeptin and pepstatin, respectively. Cathepsins B and D were visualized by electron microscopy, using CBZ-Ala- Arg-Arg-4-methoxy-beta-naphthylamine and BZ-Arg-Gly-Phe-Leu-4-methoxy-beta-naphthylamine as substrates.
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PMID:Degradation of myofibrillar proteins by cathepsins B and D. 61 6

The NH2-terminal heterogeneity which is generated in bovine GH during its extraction from mildly acidified pituitary homogenates is attributable to a newly identified peptidase. The beta-naphthylamide of Phe-Pro-Ala, modeled after the NH2-terminal tripeptide sequence of the phenylalanyl monomer of bovine growth hormone, was cleaved by the peptidase into the tripeptide and B-naphthylamine and served as a substrate for assay of the eznyme. However, the B-naphthylamide of Ala-Phe-Pro, modeled after the NH2-terminal tripeptide sequence of the alanyl monomer, was not cleaved. In harmony with this specificity, the peptidase cleaved 11 tripeptides sequentially from the NH2-terminus of the phenylalanyl monomer of bovine GH but none from the alanyl monomer. Six of the tripeptides nearest the NH2-terminus were unequivocally identified and their sequences were consistent with the NH2-terminal octadecapeptide sequence of the phenylalanyl monomer of bovine GH. Five additional peptides were by composition consistent with their being tripeptides derived from residues 19--33. Because of the apparent specificity for the hydrolytic release of tripeptides and inability to cleave substituted tripeptidyl derivatives, the enzyme is considered to be a tripeptidyl aminopeptidase. In its hydrolysis of phenylalanyl monomers of rat growth hormone, a similar number of tripeptides was released, associated with which there was a 70% loss of biological activity but no reduction in immunological activity. The enzyme could be solubilized by extraction with 1% Triton X-100 at pH 3.0, precipitated between 2 and 3 M (NH4)2SO4, and further purified by gel filtration on G-75 in M/10 acetic acid. The enzyme has a mol wt of 57,000 and is optimally active at pH 4. It can be differentiated from cathepsin D by its insensitivity to inhibition by pepstatin.
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PMID:Identification of a tripeptidyl aminopeptidase in the anterior pituitary gland: effect on the chemical and biological properties of rat and bovine growth hormones. 74 18

The effect of insulin on turnover of protein was investigated in isolated perfused rat hearts. The hormone lowered intracellular levels of nine amino acids and reduced or abolished net release of 10 amino acids and ammonia. The extent of the insulin effect on protein degradation was investigated by estimating the rate of dilution of the specific radioactivity of the free phenylalanine pool. Insulin concentrations greater than 200 microunits per ml reduced protein degradation and net phenlylalanine release. Protein degradation was estimated more directly by inhibiting reincorporation of nonradioactive phenylalanine from protein with cycloheximide. Addition of the inhibitor increased the estimated rates about 50%, but the magnitude of the hormone effect was similar. The latency of lysosomal enzymes in control and insulin-treated hearts was assessed by measuring activities of beta-acetylglucosaminidase and cathepsin D in heart homogenates in the presence and absence of Triton X-100. Perfusion with insulin-free buffer increased the activities assayable without detergent, but did not change total activities of these enzymes. Insulin decreased activities assayable without detergent and increased activities sedimenting in the 10-5 times g pellet. These studies showed that insulin restricted the rate of protein degradation in the isolated perfused rat heart. Concomitantly, the latency of lysosomal enzymes was increased when the hormone was provided.
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PMID:Effect of insulin on protein turnover in heart muscle. 111 24


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