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:3.4.25.1 (proteasome)
28,817 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have purified proteasomes to apparent homogeneity from the archaebacterium Thermoplasma acidophilum. This proteinase has a molecular mass of about 650 kDa and an isoelectric point of 5.6. The proteasome hydrolyses peptide substrates containing an aromatic residue adjacent to the reporter group, as well as [14C]methylated casein optimally at pH 8.5 and 90 degrees C. The enzyme activity is enhanced severalfold by Mg2+ and Ca2+ at 25-500 mM. This increase in activity results primarily from a change in Km. The serine-proteinase inhibitors diisopropylfluorophosphate and 3,4-dichloroisocoumarin irreversibly inhibit the enzyme, obviously by modification of both the alpha and beta subunits in the proteasome. The inhibition of proteasomal activity by the peptidylchloromethanes, Cbz-Leu-Leu-CH2Cl and Cbz-Ala-Ala-Phe-CH2Cl (Cbz, benzyloxycarbonyl), is reversible and predominantly of a competitive type. The enzyme is not activated by any of the compounds that typically stimulate the activities of the eukaryotic proteasome.
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PMID:Biochemical properties of the proteasome from Thermoplasma acidophilum. 139 84

The crystal structure of subtilisin BL, an alkaline protease from Bacillus lentus with activity at pH 11, has been determined to 1.4 A resolution. The structure was solved by molecular replacement starting with the 2.1 A structure of subtilisin BPN' followed by molecular dynamics refinement using X-PLOR. A final crystallographic R-factor of 19% overall was obtained. The enzyme possesses stability at high pH, which is a result of the high pI of the protein. Almost all of the acidic side-chains are involved in some type of electrostatic interaction (ion pairs, calcium binding, etc.). Furthermore, three of seven tyrosine residues have potential partners for forming salt bridges. All of the potential partners are arginine with a pK around 12. Lysine would not function well in a salt bridge with tyrosine as it deprotonates at around the same pH as tyrosine ionizes. Stability at high pH is acquired in part from the pI of the protein, but also from the formation of salt bridges (which would affect the pI). The overall structure of the enzyme is very similar to other subtilisins and shows that the subtilisin fold is more highly conserved than would be expected from the differences in amino acid sequence. The amino acid side-chains in the hydrophobic core are not conserved, though the inter-residue interactions are. Finally, one third of the serine side-chains in the protein have multiple conformations. This presents an opportunity to correlate computer simulations with observed occupancies in the crystal structure.
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PMID:The crystal structure of the Bacillus lentus alkaline protease, subtilisin BL, at 1.4 A resolution. 145 65

The nuclear scaffold (NS) is a proteinaceous network of orthogonally arrayed intermediate filament proteins, termed lamins, which is responsible for nuclear structure. Recent work has demonstrated that a subset of lamins A/C is proteolytically cleaved to produce an ATP-binding protein. This proteolytic cleavage is accomplished by a NS protease activity, which shows a considerable selectivity for lamins A/C and is stringently regulated by Ca2+ in vitro, suggesting that it might also participate in control of NS breakdown in various scenarios. Here, we identify the major NS protease as a novel serine protease with a predominantly chymotryptic-like substrate preference, and we show that even transient perturbations in cytosolic Ca2+ have significant effects on the NS protease activity. This NS protease activity shows extensive similarities to the multicatalytic proteinase complex. In addition to a potential role in control of NS breakdown at mitosis and/or under pathological conditions, this NS protease is also strategically located for other functions, such as inactivation of various oncogenic proteins or maturation-promoting factor.
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PMID:Ca(2+)-regulated serine protease associated with the nuclear scaffold. 146 10

Relative biological values (BV) of 36 feed phosphates were determined with female turkeys in bioassays of 21-day duration using three response criteria: weight gain, tibia ash percentage, and gain:feed ratio. Calcium phosphate, dibasic dihydrate (United States Pharmacopeia) was the reference standard. Nine mono-dicalcium phosphates (M-DCP, 21.0% phosphorus), 13 di-monocalcium phosphates (D-MCP, 18.5% phosphorus), and 14 defluorinated phosphates (DFP, 18.0% phosphorus) were evaluated. The average relative BV for M-DCP, D-MCP, and DFP samples were 97.6, 94.6, and 90.8%, respectively. Solubility of phosphates was determined by four recognized methods. The solvents were water, .4% HCl, 2.0% citric acid (CA), and neutral ammonium citrate (NAC). Water solubility of M-DCP samples was greater (67.5%) than that of D-MCP (38.8%) and DFP (8.9%) samples. Correlation of water solubility of phosphates to their relative BV was quite low, and water solubility was a poor indicator of BV. When .4% HCl was the solvent, correlation coefficients (r) were .55, .33, and .72 for M-DCP, D-MCP, and DFP, respectively. Based on these results and prediction equations, .4% HCl solubility would be inappropriate for estimating BV of M-DCP and D-MCP samples. Solubility of feed phosphates (mainly D-MCP and DFP) in 2.0% CA or NAC was positively correlated with BV; the r values were .87 to .95. Both of these solubility tests provided a good index of BV. However, it would seem inappropriate and risky to replace bioassays totally with these tests. Feed phosphate users could perform either the 2.0% CA or NAC solubility test easily as a screen for BV along with other quality control procedures (i.e., phosphorus, calcium, sodium, and fluoride determinations).
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PMID:Correlation of biological value of feed phosphates with their solubility in water, dilute hydrogen chloride, dilute citric acid, and neutral ammonium citrate. 147 May 90

The structural gene for a subtilisin J from Bacillus stearothermophilus NCIMB10278 was cloned in Bacillus subtilis using pZ124 as a vector, and its nucleotide sequence was determined. The nucleotide sequence revealed only one large open reading frame, composed of 1,143 base pairs and 381 amino acid residues. A Shine-Dalgarno sequence was found 8 bp upstream from the translation start site (GTG). The deduced amino acid sequence revealed an N-terminal signal peptide and pro-peptide of 106 residues followed by the mature protein comprised of 275 residues. The productivity of subtilisin in the culture broth of the Bacillus subtilis was about 46-fold higher than that of the Bacillus stearothermophilus. The amino acid sequence of the extracellular alkaline protease subtilisin J is highly homologous to that of subtilisin E and it shows 69% identity with subtilisin Carlsberg, 89% with subtilisin BPN' and 70% with subtilisin DY. Some properties of the subtilisin J that had been purified from the Bacillus subtilis were examined. The subtilisin J has alkaline pH characteristics and a molecular weight of 27,500. It retains about 50% of its activity even after treatment at 60 degrees C for 30 min in the presence of 2 mM calcium chloride.
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PMID:Molecular cloning of a subtilisin J gene from Bacillus stearothermophilus and its expression in Bacillus subtilis. 156 35

The role of elastase and alkaline protease in the pathogenesis of fatal infections caused by Pseudomonas aeruginosa was determined in mice treated with calcium chloride. Mortality increased significantly when solutions containing elastase were injected together with non-lethal inocula of strain PA 103, which does not produce proteolytic enzyme. In contrast, solutions containing alkaline protease did not increase mortality. In mice injected intramuscularly with strain PA 103 and calcium chloride, the organisms grew rapidly in the injected muscle but not in the liver. However, when elastase was injected together with strain PA 103 and calcium chloride, viable bacteria were also found in the liver. Moreover, the survival rate of mice challenged with elastase-producing strain 5 and calcium chloride was enhanced, and colonization of the liver prevented, by immunization with elastase toxoid. These results suggest that elastase contributes to the invasiveness of the organism.
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PMID:Role of elastase as a virulence factor in experimental Pseudomonas aeruginosa infection in mice. 161 34

The beta-amyloid protein (beta-AP) derived from a beta-amyloid protein precursor (APP) is a hallmark of Alzheimer's disease. The abundant generation of beta-AP suggests the abnormal processing of APP, but the molecular mechanism remains unclear. The main APP-processing enzyme was purified from the rat brain and identified to be a macropain-like multicatalytic proteinase. The purified enzyme cleaved the Gln15-Lys16 bond of beta-AP, but altered to cleave at the N-terminus of beta-AP to release the extracellular domain of beta-AP in the presence of Ca2+. These findings suggest that the functional change in this multicatalytic proteinase may result in abnormal processing of APP.
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PMID:Two-way cleavage of beta-amyloid protein precursor by multicatalytic proteinase. 161 99

The egg jelly-induced acrosome reaction of the sea urchin, Strongylocentrotus intermedius, was inhibited by succinyl-Leu-Leu-Val-Tyr-4-methyl-coumaryl-7-amide (Suc-Leu-Leu-Val-Tyr-MCA), but not by Suc-Ala-Ala-Pro-Phe-MCA. The proteases with hydrolytic activity toward the former were purified from sperm extract by DEAE-Sephacel and hydroxylapatite chromatographies, Sephacryl S-300 gel filtration, and heparin-Sepharose CL-6B chromatography. Two types of protease were separated, and the molecular weights were estimated to be 65 and 700 kDa, respectively, by gel filtration. The former was accompanied by hydrolytic activity toward Suc-Ala-Ala-Pro-Phe-MCA, which was not hydrolyzed by the latter. Polyacrylamide gel electrophoresis of 700 kDa protease gave a single protein band under nondenaturing conditions and at least eight bands in the range of 22-33 kDa in the presence of sodium dodecyl sulfate (SDS). The substrate specificity and the inhibitor sensitivity of 700 kDa protease indicate that it contains two types of the activity, one is chymotrypsin-type and the other trypsin-type. The former activity was enhanced by poly-L-lysine or SDS. These properties of 700 kDa protease are similar to those of proteasomes (multicatalytic proteinases) isolated from various eukaryotic sources. We had previously shown that inhibitors of chymotrypsin-like proteases inhibit the increase of intracellular Ca2+ concentration by egg jelly, resulting in the inhibition of the acrosome reaction of St. intermedius (Matsumura and Aketa, Gamete Res 23:255-266, 1989). Bringing these findings together, we suggest that the chymotrypsin-like activity of sperm proteasome participates in the onset of the acrosome reaction of St. intermedius.
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PMID:Proteasome (multicatalytic proteinase) of sea urchin sperm and its possible participation in the acrosome reaction. 187 26

The multicatalytic proteinase complex (MPC) constitutes a major nonlysosomal proteolytic system that may play an important role in the processing of biologically active peptides and enzymes, as well as in intracellular metabolism. We report that at least two of its subunits of MW 28,800 (S2) and 27,000 (S3) are phosphorylated by a cAMP-dependent protein kinase (PK-A) that copurifies with the complex isolated from bovine pituitaries. The cAMP-induced phosphorylation was time dependent and inhibited by a PK-A inhibitor. Although not an integral part of the complex, PK-A activity was still present even in 1700-fold-purified and apparently homogeneous preparations by criteria of nondissociating polyacrylamide gel electrophoresis. Furthermore, we present evidence that the copurification of the two enzymes is not species or tissue specific, or dependent on a single method of purification. The copurifying kinase was stimulated 10-fold by cAMP (10 microM) and 2- to 3-fold by a peptide substrate of the MPC, but was unaffected by protein kinase C activators (calcium and a phospholipid mixture). These findings suggest that protein phosphorylation may represent a mechanism for regulating the activity of the multicatalytic proteinase complex.
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PMID:Phosphorylation of the multicatalytic proteinase complex from bovine pituitaries by a copurifying cAMP-dependent protein kinase. 217 92

The amino acid sequence of the neutral zinc protease from Bacillus mesentericus strain 76 (MCP 76) has been determined by using peptides derived from digests with trypsin, chymotrypsin, and cyanogen bromide and from cleavage with o-iodosobenzoic acid. The peptides were purified by means of gel filtration and reversed-phase high-performance liquid chromatography and analyzed by automatic sequencing. The protein contains 300 amino acid residues. It proved to be identical with the neutral protease deduced from the DNA precursor sequence of Bacillus subtilis. The residues for zinc and substrate binding are conserved, whereas the number of calcium binding sites is reduced compared to thermolysin. A classification of the neutral zinc protease is discussed.
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PMID:Primary structure of a zinc protease from Bacillus mesentericus strain 76. 230 86


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