Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.25.1 (proteasome)
 28,817 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Lobster muscles contain a latent multicatalytic proteinase; heating at 60 degrees C for 1-2 min converts the latent form to a heat-activated form with enhanced proteolytic activity. Both forms have three endopeptidase activities, which are classified as the trypsin-like, chymotrypsin-like, and peptidylglutamylpeptide bond hydrolyzing activities. 2. Sulfhydryl reagents (mersalyl acid, N-ethylmaleimide, hemin, iodoacetamide, and p-chloromercurisulfonic acid), benzamidine, and chloromethyl ketones inhibited all three activities of the heat-activated form. Leupeptin and antipain inhibited only the trypsin-like activity, while the chymotrypsin-like activity was the most sensitive to diisopropyl fluorophosphate, phenylmethanesulfonyl fluoride, aprotinin, and soybean trypsin inhibitor. Pepstatin and L-trans-epoxysuccinylpeptides had little effect on the peptidase activities. 3. Sodium dodecyl sulfate and oleic acid preferentially activated the peptidylglutamyl-peptide hydrolyzing activity of the latent form, whereas N-ethylmaleimide stimulated both the trypsin-like and peptidylglutamyl-peptide hydrolases. These results suggest that the lobster enzyme is an atypical serine proteinase.
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PMID:Differential effects of oleic acid, sodium dodecyl sulfate, and protease inhibitors on the endopeptidase activities of the lobster multicatalytic proteinase. 176 21

When dialyzed extracts from hake (Merluccius hubbsi) skeletal muscle were chromatographed in DEAE-Sephacel, an alkaline protease (37 degrees C, pH 8.5) and a trypsin inhibitor were isolated. The enzyme showed its maximal activity against azocasein in the range of pH between 7 and 9. The protease was able to hydrolyze the trypsin substrates Bz-Arg-OEt and Tos-Arg-OMe and did not cleave the chymotrypsin substrate Bz-Tyr-OEt. The enzyme was strongly inhibited by several serine protease inhibitors, whereas inhibitors of the other types of proteases scarcely affected it. The protease was able to degrade the major contractile and cytoskeletal constituent proteins of myofibrils and to accumulate acid-soluble products. The protease activity was completely suppressed by the addition of the trypsin inhibitor isolated from the same muscle. These results indicate that hake skeletal muscle contains a trypsin-like serine protease which might be involved in the catabolism of myofibrillar proteins, as well as in the proteolytic events that take place during post mortem storage of fish muscle.
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PMID:Detection of a trypsin-like serine protease and its endogenous inhibitor in hake skeletal muscle. 189 57

A high-molecular-weight (Mr 740,000) multicatalytic proteinase (MCP) was purified over 3100-fold from soluble extracts of lobster claw and abdominal muscles. The enzyme was extracted from muscle in a latent state; brief (3 min) heating of an ammonium sulfate fraction (45-65% saturation) at 60 degrees C irreversibly activated the proteinase while denaturing about 55% of the protein. MCP was further purified by chromatography on two sequential arginine-Sepharose columns and a Mono Q column with a yield of 60%. About 1.12 mg MCP was obtained for every 100 g tissue. In addition to [14C]methylcasein, the MCP hydrolyzed synthetic peptide substrates of trypsin and chymotrypsin at pH 7.75. Serine protease inhibitors (diisopropyl fluorophosphate, phenylmethanesulfonyl fluoride, aprotinin, benzamidine, soybean trypsin inhibitor, chloromethyl ketones), leupeptin, antipain, hemin, sulfhydryl-blocking reagents (N-ethylmaleimide, mersalyl acid, p-chloromercurisulfonic acid, iodoacetamide) suppressed activity while Ep-475, a specific inhibitor of cysteine proteinases, had no effect, suggesting the MCP is a serine proteinase with one or more cysteine residues indirectly involved in catalysis. The latent MCP was purified using the same procedure as that for the active form, except that thermal activation was omitted. The elution characteristics of latent MCP from the arginine-Sepharose and Mono Q columns were identical to those of active MCP. Since the purified latent form could still be activated by heating, activation did not involve denaturation of an endogenous inhibitor or substrate. Subunit compositions of both forms were identical in two-dimensional polyacrylamide gels; each was composed of eight polypeptides with molecular weights between 25,000 and 32,500 and a ninth polypeptide with a molecular weight of 41,000. Electron microscopy of negatively stained material showed that each form was a cylinder-shaped particle (approximately 10 x 15 nm) consisting of a stack of four rings with a hollow center; no differences in shape, dimensions, or submolecular structure were observed. These results suggest that activation probably involved small conformational changes rather than covalent modifications or rearrangement of subunits within the complex.
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PMID:Purification and characterization of a multicatalytic proteinase from crustacean muscle: comparison of latent and heat-activated forms. 267 43

A nonlysosomal alkaline protease which degrades the oxidatively modified form of Escherichia coli glutamine synthetase has been purified to apparent homogeneity from rat and mouse liver acetone powders. Its molecular weight was determined to be 300,000 by Sephacryl S-300 gel filtration but results of further studies using high pressure liquid chromatography gel filtration suggest a value of 650,000. Examination of the subunit structure by sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed multiple bands of molecular weights between 22,000 and 34,000. The alkaline protease was inhibited by thiol reagents. Phenylmethylsulfonyl fluoride, aprotinin, leupeptin, antipain, and chymostatin partially inhibited the protease. The inhibition by phenylmethylsulfonyl fluoride was prevented by dithiothreitol, and alpha 1-antitrypsin and soybean trypsin inhibitor did not inhibit. No inhibition was observed with metalloprotease inhibitors. The alkaline protease is active over a broad range of pH with optimum activity for the degradation of oxidized glutamine synthetase around pH 9.0. Its activity is not stimulated by MgATP. A study of the products of insulin B chain degradation demonstrated major cleavage sites at Gln13-Ala14, Leu15-Tyr16, Cys(SO3H)19-Gly20, Gln4-His5, and Leu17-Val18. Based on its endopeptidase activity and its inhibitor specificity, the alkaline protease should be classified as a cysteine proteinase. It appears to be distinct from previously described proteinases and is likely involved in nonlysosomal mechanisms of intracellular protein turnover.
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PMID:Purification of a liver alkaline protease which degrades oxidatively modified glutamine synthetase. Characterization as a high molecular weight cysteine proteinase. 286 41

It was found that the acid protease of Fusarium culmorum can hydrolyze various proteins of plant origin including polygalacturonase inhibitor from bean (BPI) and soybean trypsin inhibitor (STI). The highest hydrolysis extent of BPI and STI by the enzyme was only 5% and 3% respectively. The partially hydrolyzed BPI lost its inhibition ability to fungal polyglacturonases. Similarly, the partially hydrolyzed STI lost its inhibition ability to trypsin and fungal alkaline protease. The F. culmorum acid protease showed broad substrate specificity towards synthetic dipeptides.
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PMID:Hydrolytic ability of acid protease of Fusarium culmorum and its possible role in phytopathogenesis. 620 29

It was previously reported that, in addition to a known chymotrypsin-like protease capable of hydrolyzing histones with an optimum pH of 8 (neutral protease), another protease is bound to the chromatin of various rat tissues and in situ hydrolyzes casein more quickly than histones with an optimum pH of 10 (alkaline protease). In the present study, the alkaline protease was purified 14 000-fold to approx. 75% purity from the chromatin of Rhodamine sarcoma. This tumor contains both proteases at higher levels than normal tissues. For purification, affinity columns of Sepharose with bound soybean trypsin inhibitor, casein and histones were successively used. Also, the neutral protease was purified 920-fold to an apparently homogeneous state by affinity chromatography on a Sepharose column with bound soybean trypsin inhibitor under conditions, in which an excess amount of the enzyme was applied on the column so that part of the enzyme would pass through the column without adsorption and the enzyme thus adsorbed was then eluted. The purified alkaline and neutral proteases had molecular weights of approx. 18 000 and 27 000, respectively, and isoelectric points of approx. 11. The former enzyme hydrolyzed casein (100) in preference to histones (18) with an optimum pH of 9.5, whereas the latter enzyme preferred histones (100) to casein (32) with an optimum pH of 8. Their actions against other proteins and synthetic substrates were also studied.
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PMID:Purification and characterization of alkaline protease and neutral protease from chromatin of rats. 702 44

The activity of insulin-degrading enzyme (IDE), a thiol metalloprotease degrading insulin in many insulin target cells, was determined in human colon adenocarcinoma (Caco-2) cells. Insulin-degrading activity was localized in the cytosol of Caco-2 cells, accounting for 88% of total activity. Western blots and immunoprecipitation showed that IDE was present in the cytosol of Caco-2 cells and contributed to more than 93% cytosolic insulin-degrading activity. Cytosolic insulin degradation was strongly inhibited by IDE inhibitors, including N-ethylmaleimide, 1,10-phenanthroline, p-chloromericuribenzoate, and EDTA, but was not significantly or not as extensively inhibited by strong inhibitors of proteasome, i.e., chymostatin, soybean trypsin inhibitor, leupeptin, and Dip-F. These results suggest that IDE is present in Caco-2 cells, that Caco-2 IDE has properties similar to those of its counterparts in insulin-target tissues, and that it significantly contributes to intracellular insulin degradation.
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PMID:Insulin-degrading enzyme in a human colon adenocarcinoma cell line (Caco-2). 759 85

Among various protease inhibitors, chymostatin (an inhibitor of sperm chymotrypsin-like protease) strongly inhibited the binding of sperm to the vitelline coat of glycerinated eggs of the ascidian Halocynthia roretzi, whereas leupeptin (an inhibitor for sperm acrosin), antipain, and soybean trypsin inhibitor had no significant inhibitory effects. Dansyl-Val-Pro-argininal (an inhibitor of the sperm trypsin-like protease, spermosin) had an inhibitory effect on the binding of sperm that was much smaller than its effects on fertilization. Since the sperm chymotrypsin-like protease that is involved in ascidian fertilization has been identified as a proteasome (multicatalytic proteinase complex), we tested the effects of several peptidyl argininals, inhibitors of the activities of proteasomes, on this binding process. The ranking of the inhibitory effects of these compounds on the binding of sperm was the same as that of their effects on the chymotrypsin-like activity of the proteasome, reported previously. The potent inhibitors of binding used in these studies had no or minimal effects on sperm motility. These results suggest that a sperm chymotrypsin-like protease (most probably the chymotrypsin-like protease in the proteasome) plays a key role in binding of sperm to the vitelline coat of the ascidian egg.
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PMID:Effects of protease inhibitors on binding of sperm to the vitelline coat of ascidian eggs: implications for participation of a proteasome (multicatalytic proteinase complex). 837 53

The circumstances which permit the establishment of Leishmania infections in sandflies were investigated by altering the growth conditions for L. donovani parasites in the unsuitable vector Phlebotomus papatasi. Only 5.0% of the sandflies harboured a few parasites 3 days after feeding on promastigotes in defibrinated blood. Heparinized blood or the addition of trypsin inhibitor to the meals allowed persistence of infections (day 6) in 9.9% and 25.8% of the flies respectively. Meals of erythrocytes, saline and amastigotes produced 44.4% fly infection on day 6, while similar promastigote-initiated infections remained in 70.3% of the flies. Proteolytic activities in the guts of sandflies fed on the above meals without parasites, were the highest after defibrinated bloodmeals. Erythrocytes with saline decreased the maximal alkaline protease level from 20.8 U to 13.5 U/fly; that of trypsin from 3.9 U to 1.8 U/fly and that of the aminopeptidase from 5.5 U to 3.9 U/fly. After meals of heparinized blood, the maximal alkaline protease activity (12.0 U/fly) was also much lower than after defibrinated blood-feeding. The different diets which resulted in comparatively low enzymatic activities, including blood with trypsin inhibitor, also promoted the survival of infections. This implies that the proteolytic activity in the sandfly gut modulates the vector susceptibility.
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PMID:Resistance of Phlebotomus papatasi to infection with Leishmania donovani is modulated by components of the infective bloodmeal. 983 11

In the compatible interaction between Arabidopsis thaliana and the endoparasitic nematode Meloidogyne incognita, galls are formed on the roots of the host plant. Differential display was used to identify alterations of gene expression in young A. thaliana root galls caused by M. incognita. Six genes were confirmed as plant genes by DNA gel blot hybridizations. Significant homology was found with a trypsin inhibitor, peroxidase, mitochondrial uncoupling protein, endomembrane protein, 20S proteasome alpha-subunit, and diaminopimelate decarboxylase. The cellular and temporal expression of each of the six genes was analyzed by mRNA in situ hybridizations.
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PMID:Arabidopsis thaliana genes expressed in the early compatible interaction with root-knot nematodes. 1127 26


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