Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.17 (lysozyme)
 21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

When the cell wall of Bacillus subtilis is removed by lysozyme and the resultant protoplasts are plated on hypertonic soft agar medium, each protoplast forms an L colony. L bodies from such L colonies again plate as L-colony-forming units (CFU). However, if protoplasts or L bodies are "conditioned" by 1 h of incubation in 0.4% casein hydrolysate medium and then incubated in 25% gelatin medium for 1 h, 60 to 100% of the formerly naked cells give rist to bacillary colonies. The present experiments largely explain the mechanism responsible for the "heritable" persistence of the wall-less state in B. subtilis. It is shown that protoplasts produce a reversion inhibitory factor (RIF) which blocks reversion when the cell concentration exceeds 5 x 105 CFU/ml. This inhibitor is nondialyzable and sensitive to trypsin, heat, and detergent. Efficient reversion at 2 x 107 CFU/ml is obtained if the protoplasts are treated with trypsin after conditioning and chloramphenicol is incorporated into the gelatin reversion medium. In the presence of 500 mug of trypsin per ml, the requirement for gelatin is sharply reduced, and reversion occurs rapidly in liquid medium containing only 10% gelatin. Trypsin also stimulates reversion in L colonies growing on soft agar. Latent RIF is activated by beta-mercaptoethanol. This reagent blocks reversion of protoplast suspensions at densities of 5 x 105 CFU/ml. Comparison of the autolytic behavior of B. subtilis and of the RIF revealed that several or the properties of the two activities coincide: both are inhibited by high concentrations of gelatin, both are activated by beta-mercaptoethanol, and both have high affinity for cell wall. Going on the assumption that RIF is autolysin, models for protoplast reversion is suggested by the finding that mutants with altered teichoic acid show altered reversion behavior.
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PMID:Inhibitory protein controls the reversion of protoplasts and L forms of Bacillus subtilis to the walled state. 40 56

A new rapid method for the quantitative and routine determination of free amino groups in intact pure proteins has been developed. Primary amino groups are labeled with fluorescamine and the labeled groups are detected by absorption spectroscopy in the range 375-390 nm. The amino group concentration can be determined in a few minutes without hydrolyzing the labeled protein and extracting a lysine derivative. The method was tested with the following proteins: lysozyme, alpha-lactalbumin, beta-lactoglobulin, bovine serum albumin, ribonuclease, ribonuclease-S-peptide, and alphasl-casein B. Application of this method to the estimation of available lysine is discussed.
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PMID:New method for determination of free amino groups in intact pure proteins: relationship to available lysine. 99 78

An inhibitory protein for the 20S proteasome (also known as macropain, the multicatalytic proteinase complex and 20S proteinase) has been purified from bovine red blood cells. The inhibitor has an apparent molecular weight of 31,000 on SDS-PAGE and appears to form multimers under nondenaturing conditions. This protein inhibited all three of the putatively distinct catalytic activities of proteasome A (the active form of the proteinase) characterized by the hydrolysis of synthetic peptides such as Z-VLR-MNA, Z-GGL-AMC or Suc-LLVY-AMC and Z-LLE-beta NA. The inhibitor also prevented the hydrolysis of large protein substrates such as casein, lysozyme and bovine serum albumin. Proteasome L (the latent form of the proteinase) does not degrade these large protein substrates, but does hydrolyze the three synthetic peptides at rates similar to those by proteasome A. The inhibitor inhibited only two of these peptidase activities of proteasome L (hydrolysis of Z-GGL-AMC and of Z-LLE-beta NA or Suc-LLVY-AMC); it had no effect on the hydrolysis of Z-VLR-MNA. The inhibitor was specific for inhibition of the proteasome and had no effect on the activity of any other proteinase tested including trypsin, chymotrypsin, papain, subtilisin and both isoforms of calpain. Kinetic analysis indicates that the inhibitor interacted with the proteasome by a mechanism involving tight-binding. Because the proteasome appears to be a key component of the ATP/ubiquitin-dependent pathway of intracellular protein degradation, the inhibitor may represent an important regulatory protein of this pathway.
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PMID:Purification and characterization of a protein inhibitor of the 20S proteasome (macropain). 131 59

A protein that greatly stimulates the multiple peptidase activities of the 20 S proteasome (also known as macropain, the multicatalytic protease complex, and 20 S protease) has been purified from bovine red blood cells and from bovine heart. The activator protein was a single polypeptide with an apparent molecular weight of 28,000, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and had a native molecular weight of approximately 180,000. This protein, which we have termed PA28, regulated all three of the putatively distinct peptidase activities displayed by each of two functionally different forms of the proteasome. This regulation usually included both an increase in the maximal reaction velocity and a decrease in the concentration of substrate required for half-maximal velocity and indicated that PA28 acted as a positive allosteric effector of the proteasome. PA28 failed, however, to stimulate the hydrolysis of large protein substrates such as casein and lysozyme. These results suggested that the hydrolysis of protein substrates occurred at a site or sites distinct from those that hydrolyzed small peptides and that the regulation of the two processes could be uncoupled. Evidence for direct binding of PA28 to the proteasome was obtained by glycerol density gradient centrifugation. PA28 may play an important regulatory role in intracellular proteolytic pathways mediated by the proteasome.
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PMID:Identification, purification, and characterization of a protein activator (PA28) of the 20 S proteasome (macropain). 158 32

A serine protein kinase that phosphorylates the beta-subunit of the insulin receptor has been partially purified 5,000-fold from HeLa cell membranes. The enzyme has been purified by ion-exchange and hydroxylapatite chromatography and sucrose gradient centrifugation; it has an apparent molecular weight of 36,000-43,000 daltons. It exhibits the following properties: (a) it catalyzes the phosphorylation of the autophosphorylated insulin receptor more efficiently than the nonautophosphorylated insulin receptor, (b) it decreases insulin receptor phosphorylation of tubulin but has no effect on insulin receptor phosphorylation of microtubule-associated proteins or reduced and carboxyamidomethylated lysozyme. The enzyme also phosphorylates casein and ribosomal protein S6 and shares many properties with casein kinase I: (a) similar molecular weight, (b) utilization of ATP but not GTP as phosphoryl donor, and (c) sensitivity to inhibition by heparin. Based on several criteria the receptor serine kinase is neither protein kinase C nor the cAMP-dependent protein kinase.
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PMID:Phosphorylation of the insulin receptor by a casein kinase I-like enzyme. 164 67

The classical hydrolysis of proteins with hydrochloric acid using tryptamine [3-(2-aminoethyl)indole] as additive revealed that tryptophan can be measured without destruction together with other amino acids by gas chromatography. An extensive study was made to establish the optimum conditions for protein hydrolysis (time and temperature of hydrolysis, amount of tryptamine) and for the derivatization of amino acids. The amino acid contents (including tryptophan) of standard proteins such as lysozyme, bovine and human albumin, human gamma-globulin, casein and alpha-chymotrypsin and protein matrices (meat and fish meals, sunflower) were determined, after hydrochloric acid hydrolysis (4 h, 145 degree C) in the presence of tryptamine. as N, O, (S)-trifluoroacetyl isobutyl esters with SE-30 as the stationary phase. The reproducibility of the measurements was 4.6% (relative standard deviation) or less.
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PMID:Gas chromatography of tryptophan together with other amino acids in hydrochloric acid hydrolysates. 170 86

Four examples of a mesenchymal tumor of undetermined histogenesis occurred in three mixed-breed dogs and one Yorkshire terrier. All tumors occurred as solitary, soft to firm, solid, tan, and ulcerated masses in the digits of dogs aged 11 to 15 years. The compact cellular tumor had cells with anisokaryotic round, oval, or irregular nuclei, some of which were multinucleated. The neoplastic cells appeared to arise in the tissue near the third phalanx in the area of dense collagenous trabeculae located proximal to the fat pad and sweat glands. The unclassifiable cells had some features of histiocytes by transmission electron microscopy, but failed to stain for lysozyme and alpha-1-antichymotrypsin, markers for monocyte-macrophage derived cells. Immunohistochemically, the cells stained for vimentin but not for cytokeratins, desmin, S-100 protein, epithelial membrane antigen, alpha-lactalbumin, lysozyme, alpha-1-antichymotrypsin, alpha-lactalbumin, casein, and heavy and light chain immunoglobulins. The combined findings of light and transmission electron microscopy and immunohistochemistry exclude tumor histogenesis from an epithelial cell, melanocyte, mast cell, plasma cell, Schwann cells, and Merkel cell.
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PMID:Distinctive unclassified mesenchymal tumor of the digit of dogs. 175 Jan 65

1. Murine macrophages showed a considerably higher in vitro arginase production in short time cultures than rat peritoneal cells. 2. The in vivo stimulation with casein or thioglycollate resulted in an enhanced in vitro enzyme production in mice. 3. The adherence is not the condition of the enzyme production. 4. The difference between the two species cannot be explained by the lack of bivalent ions, the absence of energy supply, proteolysis, the low number of macrophages or by the different cell types of the peritoneal exudate of mouse and rat. 5. The lysozyme production of murine and rat peritoneal macrophages was also investigated and no difference was observed between the two species.
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PMID:Differences in the arginase activity produced by resident and stimulated murine and rat peritoneal macrophages. 178 60

A metallo-endopeptidase, which appears to be an integral membrane protein of rat kidney, was purified to homogeneity by a series of standard chromatographic procedures. This enzyme significantly hydrolyzed human parathyroid hormone [hPTH(1-84)] and a synthetic substrate Suc-Leu-Leu-Val-Tyr-Mec (Suc = succinyl, Mec = 4-methyl-coumarinyl-7-amide). The purified enzyme had apparent molecular masses of 250 kDa on gel filtration, and 88 kDa and 245 kDa on sodium dodecyl sulfate/polyacrylamide gel electrophoresis under reducing and non-reducing conditions, respectively. Its pH optimum for activity was 8.0-8.5 and its isoelectric point was pH 4.9. Its activity was inhibited by EDTA, EGTA and o-phenanthroline, but not by phosphoramidon. The metal-depleted enzyme was reactivated by the addition of metal ions. The enzyme was also inhibited by chymostatin and eglin C, and by thiol compounds. Of the synthetic substrates examined, the enzyme hydrolyzed only Suc-Leu-Leu-Val-Tyr-Mec, one of the synthetic substrates for alpha-chymotrypsin. It did not hydrolyze synthetic substrates with less than four amino acid residues with tyrosine in the P1 position. The enzyme hydrolyzed hPTH and reduced hen egg lysozyme but did not hydrolyze azocasein or [3H]methyl-casein. NH2-terminal amino acid sequence analyses of the degradation products of hPTH(1-84) and reduced hen egg lysozyme by the purified enzyme revealed that the enzyme preferentially cleaved these peptides at peptide bonds flanked by hydrophilic amino acid residues. Amino acid analyses showed that the main degradation products of PTH were hPTH(17-29), hPTH(30-38) and hPTH(74-84). The ability of the enzyme to hydrolyze peptide bonds flanked by hydrophilic amino acid residues and its inability to degrade azocasein distinguish it from several other kidney endopeptidases reported, such as endopeptidase 24.11 and meprin.
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PMID:A membrane-bound metallo-endopeptidase from rat kidney hydrolyzing parathyroid hormone. Purification and characterization. 188 19

Mammalian cells contain two large proteolytic complexes, the 650-kDa proteasome (or multicatalytic protease) and the 1500-kDa (26 S) Ubiquitin-conjugate-degrading enzyme. Since the proteasome is also required for the ATP-dependent degradation of ubiquitinated proteins, we tested whether it may be a component of the larger complex. The proteasome normally is soluble in 38% ammonium sulfate. However, after preincubation of reticulocyte extracts with ATP, several proteasome activities appeared in the 38% ammonium sulfate pellet, including the ability to degrade hydrophobic peptides and 14C-casein. Also, following preincubation with ATP, the precipitable fraction could degrade 125I-lysozyme-ubiquitin (Ub) conjugates. The activities were not present after incubation without ATP or with a nonmetabolizable ATP analog. Nondenaturing gel electrophoresis indicated the ATP-dependent appearance of a new band which degraded proteasome substrates, and reacted with an anti-proteasome monoclonal antibody on Western blot. This new band appeared larger than the proteasome and migrated similarly to the larger Ub-conjugate-degrading complex. The formation of the larger complex required factor(s) present in the 38% ammonium sulfate pellet and either the 40-80% fraction or the purified proteasome from reticulocytes or muscle. After complex formation, hydrolysis of Ub-protein conjugates and also the non-ubiquitinated substrate, casein, was stimulated severalfold by ATP, but non-metabolizable ATP analogs had little or no effect. Thus, the proteasome corresponds to component CF-3 of Ganoth et al. (Ganoth, D., Leshinisky, E., Eytan, E., and Hershkov, A. (1989) J. Biol. Chem. 263 12412-12419) and undergoes an energy-dependent association with other factors to form the 1500-kDa, ATP-requiring proteolytic complex.
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PMID:The proteasome (multicatalytic protease) is a component of the 1500-kDa proteolytic complex which degrades ubiquitin-conjugated proteins. 218 Sep 50


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