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)

Autolysis of Enterococcus hirae ATCC 9790 is the result of the action of endogenous enzymes that hydrolyze bonds in the protective and shape-maintaining cell wall peptidoglycan. It is thought that these potentially suicidal enzymes play a positive role(s) in wall growth and division and are expressed as autolysins when cell wall assembly and/or repair are inhibited. E. hirae possesses two potentially autolytic enzymes, both of which are muramidases. Although they hydrolyze the same bond as hen egg-white lysozyme, both are high-molecular-mass, complex enzymes. Muramidase-1 is synthesized as a zymogen, requiring protease activation. It is a glucoenzyme that is also multiply nucleotidylated with an unusual nucleotide, 5-mercaptouridine monophosphate. Muramidase-2 is almost certainly a product of a separate gene. The deduced amino acid sequence of a cloned gene for extracellular muramidase-2 showed several unusual features. It appears to be a two-, or perhaps three-domain protein with a putative glycosidase-active site near the N-terminal end and six 45-amino-acid-long repeats at the C-terminal end which are presumed to be involved with high-affinity binding to the insoluble peptidoglycan substrate. Muramidase-2 binds penicillin with low affinity. The presence of several amino acid groupings characteristic of serine-active site beta-lactam-interactive proteins is consistent with the possible presence of a penicillin-binding, third domain. Indirect evidence consistent with a role(s) for these enzymes in cell wall growth and division has been obtained. However, proof of such role(s) awaits modern genetic, molecular, and biochemical analyses.
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PMID:The autolytic ('suicidase') system of Enterococcus hirae: from lysine depletion autolysis to biochemical and molecular studies of the two muramidases of Enterococcus hirae ATCC 9790. 136 71

A substantial portion of the second peptidoglycan hydrolase (muramidase-2) activity of Enterococcus hirae ATCC 9790 (formerly Streptococcus faecium) is present in the supernatant culture medium. In contrast, nearly all muramidase-1 activity is associated with cells in the latent, proteinase-activatable form. Muramidase-2 activity is produced and secreted throughout growth, with maximal levels attained at or near the end of exponential growth in a rich organic medium. Muramidase-2 activity in the culture medium remained high even during overnight incubations in the absence of proteinase inhibitors. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of supernatant culture medium concentrated by 60% saturated ammonium sulfate precipitation showed the presence of several Coomassie blue-staining bands. One intensely staining protein band, at about 71 kDa, selectively adsorbed to the insoluble peptidoglycan fraction of cell walls of E. hirae, retained muramidase-2 activity, and reacted in Western immunoblots with monoclonal antibodies to muramidase-2. The mobility of extracellular muramidase-2 in sodium dodecyl sulfate-polyacrylamide gel electrophoresis was indistinguishable from that of muramidase-2 extracted with 6 M guanidine hydrochloride from intact bacteria. Muramidase-2 appears to have only a limited number of binding sites on the peptidoglycan of E. hirae cell walls but binds with high affinity. Although high levels of muramidase-2 activity were present in supernatants of stationary-phase cultures, the bacteria were resistant to autolysis. Thus it appears that the peptidoglycan in walls of intact cells of E. hirae is somehow protected from the hydrolytic action of extracellular muramidase-2.
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PMID:Extracellular and cellular distribution of muramidase-2 and muramidase-1 of Enterococcus hirae ATCC 9790. 157 92

Bordetella pertussis Tohama phases I and III were grown to the late-exponential phase in liquid medium containing [3H]diaminopimelic acid and treated by a hot (96 degrees C) sodium dodecyl sulfate extraction procedure. Washed sodium dodecyl sulfate-insoluble residue from phases I and III consisted of complexes containing protein (ca. 40%) and peptidoglycan (60%). Subsequent treatment with proteinase K yielded purified peptidoglycan which contained N-acetylglucosamine, N-acetylmuramic acid, alanine, glutamic acid, and diaminopimelic acid in molar ratios of 1:1:2:1:1 and less than 2% protein. Radiochemical analyses indicated that 3H added in diaminopimelic acid was present in peptidoglycan-protein complexes and purified peptidoglycan as diaminopimelic acid exclusively and that pertussis peptidoglycan was not O acetylated, consistent with it being degraded completely by hen egg white lysozyme. Muramidase-derived disaccharide peptide monomers and peptide-cross-linked dimers and higher oligomers were isolated by molecular-sieve chromatography; from the distribution of these peptidoglycan fragments, the extent of peptide cross-linking of both phase I and III peptidoglycan was calculated to be ca. 48%. Unambiguous determination of the structure of muramidase-derived peptidoglycan fragments by fast atom bombardment-mass spectrometry and tandem mass spectrometry indicated that the pertussis peptidoglycan monomer fraction was surprisingly homogeneous, consisting of greater than 95% N-acetylglucosaminyl-N-acetylmuramyl-alanyl-glutamyl-diaminopimelyl++ +-alanine.
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PMID:Structure of Bordetella pertussis peptidoglycan. 288 47

Seventeen meningeal tumors were examined for pathology with electron microscopy and immunohistochemistry including glial fibrillary acidic protein (GFAP), S-100 protein, muramidase, and factor VIII. These tumors included seven meningiomas, one hemangiopericytoma, three meningeal sarcomas (1 pleomorphic-cell type and 2 myxofibrosarcomas), two fibrous histiocytomas, and four malignant melanomas. Two of seven children with meningioma had a poor outcome despite the benign histological features of the tumor. S-100 protein was present in the two tumors. All three children with meningeal sarcoma had a rapid downhill clinical course, although the myxofibrosarcoma initially had a relatively benign histological appearance. The two children with fibrous histiocytoma did well despite the aggressive histological features. Muramidase was a good marker of such tumors. Because of the morphological difficulties associated with childhood meningeal tumors, both electron microscopy and immunohistochemistry can be of diagnostic benefit.
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PMID:Meningeal tumors of infancy and childhood. 300 8

Neoplastic angioendotheliomatosis (NAE) is a rare entity characterized by multifocal, intravascular proliferation of large pleomorphic cells within small vessels of most organs, with a particular affinity for the central nervous system. Clinically, patients with NAE present with focal neurologic signs and a progressive decline in mental status, followed by death in a few months. The histogenesis of NAE is controversial but has been previously thought to represent a malignant proliferation of endothelial cells. Three autopsy cases with clinical and histologic features of NAE were investigated by electron microscopic, standard histochemical, and immunohistochemical technics that included the use of three panleukocyte monoclonal antibodies (PLA), the endothelial-cell-specific reagents, FVIII-RAG anti-sera and Ulex europaeus agglutinin (UEA), and muramidase. The NAE cells in all three cases were stained positively by the PLA, whereas the adjacent endothelial cells and not the NAE cells were stained by FVIII-RAG and UEA. Muramidase by immunoperoxidase technic and nonspecific esterase (chloracetate) were not present in NAE cells. These results indicate that NAE is a leukocyte-derived neoplasm and not a malignant endothelial cell neoplasm. Based on these findings and on a review of the literature, it is proposed that NAE represents intravascular malignant lymphomatosis (IML). IML appears to be a primary manifestation and/or a major secondary form of disseminated malignant lymphoma. This would explain the spectrum of findings in previously reported cases.
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PMID:Neoplastic angioendotheliomatosis: immunopathologic and morphologic evidence for intravascular malignant lymphomatosis. 351 72

Group B streptococci treated with cell wall synthesis inhibitors (penicillin or vancomycin) or by a variety of membrane-acting agents are sensitized to the lytic action of exogenous M1 muramidase. Muramidase without a sensitizing agent caused rupture of bacterial chains only, accompanied by the release of a small amount of cell wall peptidoglycan label and an increase of the number of colony-forming units. In combination with sensitizing agents the exogenous muramidase appeared to initiate hydrolysis of biosynthetically new peptidoglycan. Treatment of the cells with chloramphenicol or starvation for nutritionally required amino acids suppressed the rate of cell lysis and peptidoglycan hydrolysis during subsequent sensitization and muramidase treatment of the bacteria. Purified cell walls prepared from the amino acid starved cells were also hydrolyzed with a slower rate by muramidase. It is suggested that agents sensitizing the bacteria to the exogenous muramidase act by perturbing or removing some nonmurein components of the cell envelope which protect the peptidoglycan from the activity of exogenous enzyme. Agents increasing resistance against exogenous muramidase may also cause some alteration in peptidoglycan structure.
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PMID:Factors affecting sensitivity of group B streptococci to an exogenous murein hydrolase. 389 Oct 54

The basis of the bactericidal activity of human lysozyme against Streptococcus sanguis was studied. Experiments were designed to evaluate the role of lysozyme muramidase activity in its bactericidal potency. Inactivation of the muramidase activity of lysozyme was achieved by reduction of essential disulfides with dithiothreitol (DTT) or by incubation with the chitin oligosaccharides chitotriose and chitobiose. Muramidase-inactive lysozyme, prepared by reduction with DTT, was equal in bactericidal potency to native lysozyme. Solutions of native chicken egg white lysozyme and human lysozyme exhibited equal bactericidal potency yet differed ca. fourfold with respect to lytic (muramidase) activity. The above results suggested that the bactericidal activity of lysozyme is not dependent upon muramidase activity. Chitotriose and chitobiose were found to inhibit both lytic and bactericidal activities of lysozyme. The bactericidal activity of muramidase-inactive lysozyme (reduction with DTT) was also inhibited by chitotriose and chitobiose. Further investigations demonstrated that chitotriose and chitobiose were also potent inhibitors of the bactericidal activity of the cationic homopolypeptides poly-L-arginine and poly-D-lysine. These latter results suggested that the essential bactericidal property of lysozyme was its extreme cationic nature and that some bacterial endogenous activities, inhibitable by chitotriose and chitobiose, were essential for expression of the bactericidal activity of either native or muramidase-inactive lysozyme or of the cationic homopolypeptides. Experiments with Streptococcus faecalis whole cells, cell walls, and crude autolysin preparations implicated endogenous autolytic muramidases as the bacterial targets of chitotriose and chitobiose. The essentially identical responses of S. sanguis and S. faecalis to chitotriose in bactericidal assays with muramidase-inactive lysozyme and polylysine suggested that muramidase-like enzymes exist in S. sanguis and, furthermore, play an essential role in cationic protein-induced loss of viability of the oral microbe.
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PMID:Bactericidal activity of human lysozyme, muramidase-inactive lysozyme, and cationic polypeptides against Streptococcus sanguis and Streptococcus faecalis: inhibition by chitin oligosaccharides. 392 94

Serum lysozyme (Muramidase) levels in patients with localized and generalized granuloma annulare were measured by a turbidometric method. More lysozyme is present in the serum samples of patients with generalized granuloma annulare than patients with the localized form or normal controls. The mean level of patients with generalized disease was 9.27 mg/L compared with 5.96 mg/L for patients with localized disease and 6.8 mg/L for controls.
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PMID:Serum lysozyme in patients with localized and generalized granuloma annulare. 399 8

The serum muramidase levels were measured in 128 patients with primary or metastatic colorectal cancer, 166 tumour-free patients after resection of a colorectal cancer, and 172 controls. Muramidase levels over 10 mug/ml were detected in 30%-39% of the tumour-bearing patients, in 8.2% of the tumour free, and in only 1.7% of the controls (normal level 6.68 +/- 1.42 mug/ml). Long-term follow up indicated that raised levels may occur as a transient phenomenon in recurrent or metastatic disease. The likely relation of abnormal serum muramidase activity and stimulation of the reticuloendothelial system is discussed.
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PMID:Blood muramidase activity in colorectal cancer. 415 18

Muramidase which actively lyses the cell walls of group A hemolytic streptococci has been isolated from the culture fluid of Actinomyces levoris by precipitation on ammonium sulfate, gel filtration on Sephadex G-25, ion exchange chromatography on DEAE cellulose and double electrofocusing. The enzyme thus obtained has shown its maximum activity at 40-50 degrees C. At 60 degrees C muramidase was completely inactivated. The enzyme has a wide range of optimum pH values: 5.0-9.5. The highest percentage of lysis of streptococcal cell walls has been observed in plycine-NaOH and potassium phosphate buffers at pH 8.0. Muramidase completely lysed Streptococcus pyogenes cells of different serological groups except enterococci (group D) and staphylococci. This sign allows to differentiate group D streptococcus from streptococci of other groups.
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PMID:[Isolation and evaluation of properties of muramidase causing the lysis of group A streptococci]. 718 Feb 63


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