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:3.2.1.17 (lysozyme)
21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. An autolytic endo-beta-glucosaminidase, capable of cleaving the glycoside linkages of N-unsubstituted glucosamine in the glycan moiety of cell wall peptidoglycan, was purified 470-fold from a salt extract of the 2,000 x g precipitate fraction obtained after sonication of a lysozyme-resistant strain of Bacillus cereus. The properties of this enzyme were studied. 2. The purified enzyme preparation was also active towards the glycan chain of fully N-acetylated cell wall peptidoglycan. 3. The endo-beta-glucosaminidase was inactive towards the cell wall peptidoglycan unless the peptide portion of this polymer was removed either by the action of N-acetylmuramyl-L-alanine amidase or by the treatment with alkali in aqueous dimethyl sulfoxide. 4. Studies on the action of this enzyme towards chemically modified glycans revealed that the carboxyl groups of muramic acid residues are indispensable to a substrate for this enzyme.
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PMID:Separation and characterization of an autolytic endo-beta-glucosaminidase from Bacillus cereus. 678 Mar 45

N-acetylmuramyl-L-alanine amidase (EC 3.5.1.28) specifically hydrolyzes the bacterial cell wall peptidoglycans (or mureins) and the muropeptides. The enzyme splits these molecules into two parts: the peptide subunits and the glycan strands or moieties. The bacterial peptidoglycans and their derived muropeptides display a number of biological properties. Removal of the glycosidic part of these molecules abolishes their beneficial as well as their detrimental properties. We report the high level of enzymatic activity found in all mammalian (including human) sera tested. The enzyme also occurred in human saliva, milk, cerebrospinal fluid, and synovial liquid. Mucosal tissue from different parts of the mammalian digestive tract exhibited enzymatic activity, but the enzyme was not detectable in the lumen content. The range of substrate specificity of the human enzyme was evaluated by measuring its action on the peptidoglycans extracted from several bacterial strains and representing different chemotypes and structures. Time course of the muramylalanine amidase and of the lysozyme (both of human origin) activities on some of these peptidoglycans are also reported, with the enzymes acting separately or together. From these data, we would speculate that a probable physiological role of the muramylalanine amidase is the maintenance of adequate ratios between the biologically active muropeptides and their inactive derivatives in the organism, the amidase activity antagonizing the production of biologically active molecules by lysozyme.
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PMID:The human and mammalian N-acetylmuramyl-L-alanine amidase: distribution, action on different bacterial peptidoglycans, and comparison with the human lysozyme activities. 755 13

Cell wall turnover appeared to be anomalously fast in Bacillus subtilis when the cells were grown at temperatures below 29 degrees C. Turnover rates k(generation-1), of exponential cultures at 25 degrees were approximately double those of cells grown at 37 degrees C. When autolysin levels were assayed in cell walls, it was found that the enzyme activities were constant between 25 degrees C and 40 degrees C, suggesting that there was no greater synthesis of autolysin at the lower temperature. Analyses of walls for individual components, extent of aminosugar substitution and extent of crosslinking, did not reveal significant differences between samples obtained from 25 degrees C or 37 degrees C cultures. The N-acetylmuramoyl-L-alanine amidase was stable over the temperature range studied. Lysis of cells, induced by carbonylcyanide-m-chlorophenylhydrazone, occurred at a faster rate for cells obtained at 25 degrees C than for cells obtained at 37 degrees C. In addition, the lysis of cells by hen egg white lysozyme was slightly faster when the cells were obtained from 25 degrees C cultures than from 37 degrees C cultures. It is possible the autolysin(s) responsible for cell wall turnover are cold-activated.
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PMID:Anomalies in cell wall turnover associated with the growth temperature of Bacillus subtilis. 809 13

N-Acetylmuramyl-L-alanine amidase (EC 3.5.1.28) cleaves the amide bond between N-acetyl muramic acid and L-alanine in the peptide side chain of different peptidoglycan products. The enzyme was purified from human plasma using a three-step column chromatography procedure. Monoclonal antibodies were produced against the purified human enzyme. By coupling of a high affinity monoclonal antibody to sepharose beads an immunoadsorbent column was prepared. Using this second purification method it was possible to purify large amounts of the amidase from human plasma in a single step. SDS-PAGE showed one single band of 70 kDa and two-dimensional electrophoresis showed the presence of multiple isomeric forms of the protein with pI between 6.5 and 7.9. Two different methods were used for determination of substrate specificity, a HPLC method separating peptidoglycan monomers from the reaction products after incubation with amidase and a colorimetric method when high molecular weight peptidoglycan was used as a substrate for amidase. It is shown that the disaccharide tetra peptide, disaccharide penta peptide and the anhydro disaccharide tetrapeptide are good substrates for the amidase and that muramyl dipeptide and disaccharide dipeptide are not a substrate for the amidase. Using one of the monoclonal antibodies against the amidase it was shown in FACScan analysis that N-acetylmuramyl-L-alanine amidase is present in granulocytes but not in monocytes from unstimulated peripheral blood of a healthy donor. The presence of N-acetylmuramyl-L-alanine amidase in granulocytes is a novel finding and perhaps important for the inactivation of biologically active peptidoglycan products still present after hydrolysis by lysozyme.
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PMID:Purification and characterization of N-acetylmuramyl-L-alanine amidase from human plasma using monoclonal antibodies. 860 33

N-acetylmuramyl-L-alanine amidase (NAMLAA) specifically degrades peptidoglycan, which is a major component of bacterial cell walls with strong inflammatory properties. For instance, peptidoglycan is capable of stimulating peripheral blood cells to release pro-inflammatory cytokines and is capable of inducing chronic arthritis in an animal model. In a previous study we found that degradation of peptidoglycan by purified NAMLAA reduced its inflammatory effects. To determine where NAMLAA is located in tissues, monoclonal antibodies against purified NAMLAA were produced for use in immunohistochemistry, immunoelectron microscopy, flow cytometric analysis, and Western blotting. The immunohistochemical studies showed NAMLAA-positive cells in human spleen, liver, arthritic synovial tissues, and lymph nodes. In flow cytometric studies of blood and bone marrow, neutrophilic and eosinophilic granulocytes proved to be positive. Monocytes were negative, although they do contain lysozyme, the other important peptidoglycan-degrading enzyme. However, mature macrophages obtained by bronchoalveolar lavage and subsequent selection based on autofluorescence did possess NAMLAA. In immunocytochemical staining of blood smears, thrombocytes were also positive for NAMLAA. Western blot analysis and immunoelectron microscopy of neutrophils and eosinophils showed that NAMLAA is located in azurophilic granules of neutrophils and in secretory vesicles and crystalloid-containing granules of eosinophils. Flow cytometric analysis of blood and bone marrow from different French-American-British-classified acute myeloid leukemia (AML) patients showed that AML-M2 myeloblasts were the first in the granulocyte maturation lineage that were positive for NAMLAA. The more immature AML, such as AML-M0 and AML-M1, did not express NAMLAA. CD15- and CD13-negative megakaryoblasts, corresponding to AML-M7, were also positive for NAMLAA. The expression pattern of NAMLAA in the myeloid lineage suggests that the monoclonal antibody AAA4, recognizing NAMLAA, is useful for discrimination between AML in the monocyte lineage and in the granulocyte lineage.
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PMID:Expression and intracellular localization of the human N-acetylmuramyl-L-alanine amidase, a bacterial cell wall-degrading enzyme. 924 59

N-acetylmuramyl-L-alanine amidase (NAMLAA) specifically degrades peptidoglycan, a major component of bacterial cell walls. Lysozyme degrades peptidoglycan differently by hydrolyzing the aminosugar backbone of peptidoglycan. In another study, it was shown that the two enzymes act synergistically to inactivate the inflammatory properties of peptidoglycan. The presence of lysozyme and NAMLAA was determined in serum and cerebrospinal fluid (CSF) of patients with bacterial meningitis. High concentrations of lysozyme were found in CSF while, surprisingly, NAMLAA was not present. To explain this phenomenon, the degranulation pattern of neutrophils in CSF was compared with that of neutrophils from blood. Specific granules contain lysozyme and the azurophil granules contain both lysozyme and NAMLAA. CD66b expression on the cell surface, indicative for fusion of the specific granules with the cell membrane, was higher in CSF than in blood, while the marker for the azurophil granules was lower.
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PMID:Differences in N-acetylmuramyl-L-alanine amidase and lysozyme in serum and cerebrospinal fluid of patients with bacterial meningitis. 941 76

Human N-acetylmuramyl-L-alanine amidase (EC 3.5.1.28) degrades peptidoglycan, a major component of bacterial cell walls with potent pro-inflammatory cytokine-inducing properties. We postulate that degradation of peptidoglycan by N-acetylmuramyl-L-alanine amidase is important for the inactivation of inflammatory peptidoglycan products in human tissues. The inflammatory activities of peptidoglycan digested by lysozyme and/or amidase were investigated using two properties of peptidoglycan: its capacity to induce the release of the inflammatory cytokines IL-1, IL-6 and TNF-alpha in vivo and in vitro and its capacity to induce arthritis in Lewis rats. The results show that after subsequent treatment with both lysozyme and amidase, the peptidoglycan products were unable to induce arthritis in Lewis rats. The production of pro-inflammatory cytokines in mice after intravenous injection of cell wall fragments was lower after in vitro degradation of the cell wall fragments by amidase. These in vivo results were confirmed with whole blood assays in which the production of pro-inflammatory cytokines was measured after stimulation with lysozyme- and amidase-treated peptidoglycan. The results show that human N-acetylmuramyl-L-alanine amidase possesses an enzymatic activity capable of inactivating inflammatory peptidoglycan by lowering its cytokine-inducing properties.
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PMID:Inflammatory properties of peptidoglycan are decreased after degradation by human N-acetylmuramyl-L-alanine amidase. 945 17

The peptidoglycan of Gram-positive bacteria is known to trigger cytokine release from peripheral blood mononuclear cells (PBMCs). However, it requires 100-1000 times more Gram-positive peptidoglycan than Gram-negative lipopolysaccharide to release the same amounts of cytokines from target cells. Thus, either peptidoglycan is poorly active or only part of it is required for PBMC activation. To test this hypothesis, purified Streptococcus pneumoniae walls were digested with their major autolysin N-acetylmuramoyl-L-alanine amidase, and/or muramidase. Solubilized walls were separated by reverse phase high pressure chromatography. Individual fractions were tested for their PBMC-stimulating activity, and their composition was determined. Soluble components had a Mr between 600 and 1500. These primarily comprised stem peptides cross-linked to various extents. Simple stem peptides (Mr <750) were 10-fold less active than undigested peptidoglycan. In contrast, tripeptides (Mr >1000) were >/=100-fold more potent than the native material. One dipeptide (inactive) and two tripeptides (active) were confirmed by post-source decay analysis. Complex branched peptides represented </=2% of the total material, but their activity (w/w) was almost equal to that of LPS. This is the first observation suggesting that peptidoglycan stem peptides carry high tumor necrosis factor-stimulating activity. These types of structures are conserved among Gram-positive bacteria and will provide new material to help elucidate the mechanism of peptidoglycan-induced inflammation.
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PMID:Digestion of Streptococcus pneumoniae cell walls with its major peptidoglycan hydrolase releases branched stem peptides carrying proinflammatory activity. 1021 31

A variety of pulsed-field gel electrophoresis (PFGE) protocols for the molecular subtyping of Streptococcus pneumoniae have been reported; most are time-consuming and complex. We sought to modify reference PFGE protocols to reduce the time required while creating high-quality gels. Only protocol modifications that resulted in high-quality banding patterns were considered. The following protocol components were modified. Lysis enzymes (lysozyme, mutanolysin, and RNase A) were deleted in a stepwise fashion, and then the lysis buffer was deleted. Lysis and digestion were accomplished in a single step with EDTA and N-lauroyl sarcosine (ES; pH 8.5 to 9.3) incubation at 50 degrees C in the absence of proteinase K. All enzymes except the restriction enzyme were omitted. A minimum incubation time of 6 h was required to achieve high-quality gels. All of the reactions were performed within 9 h, and the total protocol time from lysis to gel completion was reduced from 3 days to only 36 h. Combining lysis and digestion into a single step resulted in a substantial reduction in the time required to perform PFGE for S. pneumoniae. The ES solution may have caused cell lysis by activating N-acetylmuramyl-L-alanine amidase, the pneumococcal autolysin.
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PMID:Simplified protocol for pulsed-field gel electrophoresis analysis of Streptococcus pneumoniae. 1061 14

The multiplicity of murein hydrolases found in most bacteria presents an obstacle to demonstrating the necessity of these potentially autolytic enzymes. Therefore, Escherichia coli mutants with deletions in multiple murein hydrolases, including lytic transglycosylases, amidases, and DD-endopeptidases, were constructed. Even a mutant from which seven different hydrolases were deleted was viable and grew at a normal rate. However, penicillin-induced lysis was retarded. Most of the mutants were affected in septum cleavage, which resulted in the formation of chains of cells. All three enzymes were shown to be capable of splitting the septum. Failure to cleave the septum resulted in an increase in outer membrane permeability, and thus the murein hydrolase mutants did not grow on MacConkey agar plates. In addition, the hydrolase mutants not only could be lysed by lysozyme in the absence of EDTA but also were sensitive to high-molecular-weight antibiotics, such as vancomycin and bacitracin, which are normally ineffective against E. coli.
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PMID:Effects of multiple deletions of murein hydrolases on viability, septum cleavage, and sensitivity to large toxic molecules in Escherichia coli. 1239 77


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