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PubMed1975

The distribution of muramidase (lysozyme) in human tissues.

The distribution of muramidase (lysozyme) in normal and pathological human tissues has been studied, using an immunohistological technique. The enzyme was demonstrated in a variety of healthy tissues, including serous salivary acinar cells, lactating mammary tissue, Paneth cells, renal tubular cells, myeloid cells (including eosinophils), and histiocytic cells. In pathological tissues the most striking positivity was encountered in reactive histiocytic cells in granulomatous conditions such as tuberculosis and Crohn's disease. The finding of this study are related to previous reports of the distribution of human and animal muramidase and the implications of patterns of muramidase staining in pathological histiocytes are briefly discussed.

Bone Marrow↗
PubMed1982

[Isolation and evaluation of properties of muramidase causing the lysis of group A streptococci].

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.

Actinomyces↗
PubMed1987

Muramidase, alpha-1 antitrypsin, alpha-1 antichymotrypsin, and S-100 protein immunoreactivity in giant cell lesions.

A spectrum of giant cell lesions was evaluated for muramidase, alpha-1 antitrypsin, alpha-1 antichymotrypsin, and S-100 protein immunoreactivity using an avidin-biotin-complex immunoperoxidase method. Peripheral giant cell granuloma, central giant cell granuloma, giant cell tumor, osteitis fibrosa cystica, cherubism, and giant cell tumor of tendon sheath showed similar patterns of reactivity. Granulomatous inflammatory lesions stained more intensely for muramidase than did noninflammatory lesions. Alpha-1-antichymotrypsin was a slightly better marker of giant cell lesions than was alpha-1-antitrypsin. Positive S-100 protein staining in half the lesions was thought to be due to the presence of Langerhans cells. The results supported the belief that giant cell lesions of bone and tendon sheath are differentiated toward cells of the mononuclear-phagocyte system and that multinucleated giant cells are derived from macrophages.

Cherubism↗
PubMed2000

Possible correlation between urinary muramidase (E.C.3.2.1.27) and oesophageal cancer.

The diagnostic value of determination of low-mass enzymes in urine is very important, especially for early detection of some diseases. There are several investigations about lysozyme (muramidase, E.C.3.2. 1.27) and its correlation with some malignancies, but until now nothing has been reported about the lysozyme, and oesophageal cancer. This study was undertaken for determination of lysozyme concentration in urine of 32 oesophageal cancer patients to evaluate if this enzyme activity changes in oesophageal cancer used for detection of this cancer especially in its early stage. We used high performance liquid chromatography (HPLC) for determination of urinary muramidase after Sep-pac pre-purification of the samples. The mean results of lysozymuria in patients in comparison with the mean of enzyme activity in normal controls were statistically high (12.14+/-0.403 vs. 2.04+/-0.134, P</=0.001) Our finding also indicated that the severity of lysozymuria in these patients is stage dependent.

Chromatography, High Pressure Liquid↗
PubMed1990

A bacteriolytic muramidase from the basidiomycete Schizophyllum commune.

The basidiomycete Schizophyllum commune produces an extracellular bacteriolytic enzyme when grown on heat-killed cells of Bacillus subtilis as sole C, N and P source. The enzyme catalyses the dissolution of isolated B. subtilis cell walls at an optimum pH of 3.2-3.4, releasing muramyl reducing groups, which indicates that it is a muramidase. Although low levels of enzyme activity are present when the fungus is grown in the absence of bacteria, full enzyme production appears to be induced by bacterial cells and repressed by glucose. Whole bacteria are not lysed by the enzyme at pH 3.3, but are rendered osmotically fragile, and lyse when the pH is raised to 7 or higher. The muramidase is effective against several Gram-positive bacteria but did not lyse any of the Gram-negative species tested.

Bacillus subtilis↗
PubMed1987

Ultrastructural localisation of muramidase in the human synovial membrane.

The synovial intimal cell layer comprises two morphological types of cell, A and B, with an intermediate type also postulated. Type A cells show features in common with other cells of the mononuclear phagocyte system, while type B cells appear similar to fibroblasts and are assumed to have synthetic activity. Muramidase is a marker of mononuclear phagocytic cells, and we have investigated the synovial membrane for the presence of this enzyme in cells by an immunogold labelling technique. Muramidase was localised within intracytoplasmic vacuoles in subintimal macrophages and type A synoviocytes. This finding provides further evidence that type A cells are closely related to macrophages.

Aged↗
PubMed1983

[Evaluation of Ig and muramidase (lysozyme) in unspecified chronic duodenitis (bulbitis)].

In 158 patients with symptoms of non ulcerative dyspepsia, endoscopic, histologic and immunohystochemical studies were performed over three years with the aim of investigating the immunological involvement in the Chronic non specific Duodenitis (CND). After excluding 112 patients with associated pathologies of those not fulfilling technics requisites, a population of 46 subjects was selected and subsequently it was subdivided into four groups. A group of 15 patients with histologically normal duodeno served as control; the rest (31 patients) were grouped according to duodenal compromise into three groups of minor-major severity; Grade 1 (n=12); Grade 2 (n=12); Grade 3 (n=7). The number of immunoglobuline producing cells by mn2 of mucosal area and semiquantitative evaluation of mononucleated cells with cytoplasmatic activity to hydrolitic enzymes (lysozyme or muramidase) were compared among the 4 sub-groups. It was observed a variation in the immunoglobulines rate among controls (IgA: M: G=82, 52: 11, 01: 6,45) regarding the most severe degree (61, 56: 27,30: 11,14). The increase of IgMy G compared with controls was highly significant (p is less than 0.001) and it was noted a correlative IgA diminution. The contribution of hydrolitic enzymes through the presence of "activated" histiocytes was maximal in the most degree-coinciding with the increase of IgM and IgG. This findings indicated that a marked local activation of the Immunitary System type B is observed in the Chronic Nonspecific Duodenitis and its increment, expressed as quali-quantitative variations of the different immunologlobulines and muramidase producing cells, should have lythic activity in the highest degrees. We conclude, proposing this disease as a model of immunological aggression which affects bulbar mucosae.

Adult↗
PubMed1984

The mechanism of soluble peptidoglycan hydrolysis by an autolytic muramidase. A processive exodisaccharidase.

The action of purified N-acetylmuramoylhydrolase (muramidase, EC 3.2.1.17) of Streptococcus faecium ATCC 9790 on linear, uncross-linked, soluble, peptidoglycan chains produced by the same organism in the presence of benzylpenicillin was characterized as a processive exodisaccharidase. Specific labels, one [( 14C]Gal) added to the nonreducing ends of chains, and the other (3H from [3H]NaBH4) incorporated into the reducing ends of the chains, were used to establish that an enzyme molecule binds at the nonreducing terminus and sequentially hydrolyzes the glycosidic bonds, releasing disaccharide-peptide units. An enzyme molecule remains bond to a chain, and is not released at a detectable rate, until hydrolysis of that chain is complete. Reaction rates increased with the length of the polymer chain to give a maximum of 91 bonds cleaved/min/enzyme molecule for hydrolysis of a continuous polymeric substrate. The relationship between hydrolytic rate and glycan chain length is consistent with hydrolysis of bonds within the chain followed by slow release of enzyme from the distal, reducing terminus. This mechanism was experimentally confirmed by analysis of product formation during hydrolysis with stoichiometric mixtures of enzyme and soluble peptidoglycan chains. Kinetic analyses showed an apparent Km of 0.17 microM for the enzyme, independent of substrate polymer length. The dissociation constant for the initial enzyme-substrate complex was calculated to be 1.5 nM. Kinetic analyses are consistent with one catalytic site per enzyme molecule. The Kcat/Km value of 9 X 10(6) M-1 S-1 is near the limit imposed by diffusion for the initial hydrolytic events when long chains are hydrolyzed. The kinetic and physical properties of this muramidase are highly consistent with its location outside of the cellular permeability barrier and its ability to remain with and hydrolyze appropriate bonds in the cell wall in such an environment.

Binding, Competitive↗
PubMed1982

Characterization of human lysozyme (muramidase)-releasing cells. Organ distribution and functional properties as analyzed in a protein A plaque assay.

Using a modification of the protein A plaque assay, human lysozyme-releasing cells were detected as plaque-forming cells (PFC). Blood and bone marrow contained higher numbers of muramidase secretors compared to adenoid and tonsil cell suspensions. Human peripheral blood cell cultures were found to contain cells detected as PFC in the presence of antimuramidase immunoglobulin as a developing agent. Lysozyme-producing cells were also found in human bone marrow cultures. High cell densities and a short culture period were optimal conditions for lysozyme release in bone marrow cell cultures. Addition of the activating ligand lipopolysaccharide directly into the plaque assay altered the number of muramidase-secreting cells.

Antibody-Producing Cells↗
PubMed1996

Structure of a bulgecin-inhibited g-type lysozyme from the egg white of the Australian black swan. A comparison of the binding of bulgecin to three muramidases.

Bulgecin A, a bacterial metabolite, has been shown to bind in the active-site groove of the chicken-type lysozyme from the rainbow trout (RBTL) and in the lysozyme-like C-terminal domain, of a soluble lytic transglycosylase (C-SLT) from Escherichia coli. These enzymes are muramidases that cleave the glycosidic bonds in the glycan strands of the murein polymer. Here we report the crystal structure of a complex between the goose-type lysozyme from the egg white of the Australian black swan (SEWL) and bulgecin A at 2.45 A resolution. As is the case for the C-SLT/bulgecin and RBTL/bulgecin complexes, the ligand binds with the N-acetylglucosamine ring in subsite C and the proline moiety in site D where it interacts with the catalytic glutamic acid. The taurine residue interacts with the beta-sheet region. Comparisons of the three buigecin complexes show that the inhibitor has the same binding mode to the muramidases with similar protein-ligand interactions, particularly for SEWL and RBTL. From our results, it seems likely that bulgecin, in general, inhibits enzymes with lysozyme-like domains and thus might represent a novel class of natural antibiotics that act on murein-degrading rather than murein-synthesizing enzymes.

Journal Article↗
PubMed1975

Effect of Body Fluids and Macromolecular Substances on the Lysis of Group A Streptococci by Muramidases of Streptomyces albus.

The lysis of group A streptococci by muramidases of Streptomyces albus is strongly inhibited by human, rabbit, and calf serum as well as by human synovial fluids and pus. Rabbit antisera to heat-killed streptococci were no more inhibitory to the lysis of the streptococci by the lytic enzyme than normal rabbit serum. The results indicate that muramidases of S. albus will not be useful for the in vivo treatment of chronic granulomatous lesions which had been induced by insoluble cell wall components of streptococci.

Journal Article↗
PubMed1992

Modular design of the Enterococcus hirae muramidase-2 and Streptococcus faecalis autolysin.

The mature forms of the extracellular muramidase-2 of Enterococcus hirae and Streptococcus faecalis autolysin have very similar primary structures. Each consists of an active-site-containing N-terminal domain fused to a multiple-repeat C-terminal domain. Polypeptide segments occurring at equivalent places in these two bacterial wall lytic enzymes have homologues in two phage lysozymes and in three functionally unrelated proteins, illustrating the principle that protein molecules frequently are constructed from modules that are linked in a single polypeptide chain.

Amino Acid Sequence↗
PubMed2000

Varying influence of the autolysin, N-acetyl muramidase, and the cell envelope proteinase on the rate of autolysis of six commercial Lactococcus lactis cheese starter bacteria grown in milk.

The autolysin, N-acetyl muramidase (AcmA), of six commercial Lactococcus lactis subsp. cremoris starter strains and eight Lc. lactis subsp. cremoris derivatives or plasmid-free strains was shown by renaturing SDS-PAGE (zymogram analysis) to be degraded by the cell envelope proteinase (lactocepin; EC 3.4.21.96) after growth of strains in milk at 30 degrees C for 72 h. Degradation of AcmA was less in starter strains and derivatives producing lactocepin I/III (intermediate specificity) than in strains producing lactocepin I. This supports previous observations on AcmA degradation in derivatives of the laboratory strain Lc. lactis subsp. cremoris MG1363 (Buist et al. Journal of Bacteriology 180 5947-5953 1998). In contrast to the MG1363 derivatives, however, the extent of autolysis in milk of the commercial Lc. lactis subsp. cremoris starter strains in this study did not always correlate with lactocepin specificity and AcmA degradation. The distribution of autolysins within the cell envelope of Lc. lactis subsp. cremoris starter strains and derivatives harvested during growth in milk was compared by zymogram analysis. AcmA was found associated with cell membranes as well as cell walls and some cleavage of AcmA occurred independently of lactocepin activity. An AcmA product intermediate in size between precursor (46 kDa) and mature (41 kDa) forms of AcmA was clearly visible on zymograms, even in the absence of lactocepin I activity. These results show that autolysis of commercial Lc. lactis subsp. cremoris starter strains is not primarily determined by AcmA activity in relation to lactocepin specificity and that proteolytic cleavage of AcmA in vivo is not fully defined.

Animals↗
PubMed2001

A new lysozyme fold. Crystal structure of the muramidase from Streptomyces coelicolor at 1.65 A resolution.

Cellosyl is a bacterial muramidase from Streptomyces coelicolor. Similar to other lysozymes, the enzyme cleaves the beta-1,4-glycosidic bond between N-acetylmuramic acid and N-acetylglucosamine units, but it also exhibits a beta-1,4-N,6-O-diacetylmuramidase activity. The latter enables Cellosyl to degrade the cell walls of Staphylococcus aureus, which are not hydrolyzed by chicken-, goose-, or bacteriophage T4-type lysozymes. The enzymatic activity and amino acid sequence of Cellosyl group it with lysozymes of the Chalaropsis type, for which no detailed structural information has been available so far. The crystal structure of Cellosyl from S. coelicolor has been determined to a resolution of 1.65 A and refined to an R-factor of 15.2%. The enzyme is comprised of a single domain and possesses an unusual beta/alpha-barrel fold. The last strand, beta 8, of the (beta/alpha)(5)beta(3)-barrel is found to be antiparallel to strands beta 7 and beta 1. Asp-9, Asp-98, and Glu-100 are located at the active site. The structure of Cellosyl exhibits a new lysozyme fold and represents a new class of polysaccharide-hydrolyzing beta/alpha-barrels.

Amino Acid Sequence↗
PubMed1983

An immunohistochemical study of hemoglobin A, hemoglobin F, muramidase, and transferrin in erythroid hyperplasia and neoplasia.

The bone marrow biopsy specimens of 35 patients with benign and malignant erythroid hyperplasias were examined for the presence of hemoglobin A, hemoglobin F, muramidase (lysozyme), and transferrin, using an indirect immunoperoxidase method (PAP) on Zenker's-fixed paraffin-embedded bone marrow biopsy specimens and particles. Five cases of each of the following entities were studied: erythroleukemia and erythremic myelosis, acute granulocytic leukemia with maturation (FAB M2), polycythemia rubra vera, myeloproliferative syndrome in childhood, megaloblastic anemia (B12 and folate deficiency), erythroid hyperplasia (regenerating bone marrow and hemolytic anemia), and Ph' chromosome positive chronic granulocytic leukemia. Hemoglobin A was present in both the early and late erythroid precursors in all conditions. Hemoglobin F was the predominant hemoglobin in early erythroblasts of pernicious anemia and in both early and late erythroid elements in erythroleukemia and erythremic myelosis. Small quantities of hemoglobin F were present in a few isolated clusters in other conditions. Staining for hemoglobin F may be useful in identifying immature erythroid precursors and in distinguishing some cases of dysplastic erythroid hyperplasia from neoplasia. Additionally, these findings suggest that the maturational switch in hemoglobin synthesis operates with distinct pathways under different conditions.

Bone Marrow↗
PubMed1994

Gene XV of bacteriophage PRD1 encodes a lytic enzyme with muramidase activity.

Bacteriophage PRD1 is a lipid-containing virus that infects a variety of Gram-negative bacteria, including Escherichia coli. The phage lyses its host by virtue of a virally-encoded lytic enzyme, the synthesis of which has been assigned to gene XV on the basis of complementation analysis and experiments with mutant phages. We report here the cloning of gene XV into an expression plasmid and the purification of its product, protein P15, to near homogeneity. The purified protein P15, identified by N-terminal sequence analysis, showed a strong lytic activity against chloroform-treated Gram-negative cells. No activity against Gram-positive bacterial species could be detected. The pH optimum of the enzyme was between 7.0-8.0. Protein P15 was readily inactivated at temperatures above 4 degrees C, as well as by increasing the ionic strength of the buffers. The analysis of cell wall digests indicated that P15 is a glycosidase that cleaves the beta (1-4) linkage between N-acetylmuramic acid and N-acetylglucosamine, thus displaying muramidase activity.

Amino Acid Sequence↗
PubMed1992

Cloning and nucleotide sequence of the gene encoding the 136-kilodalton surface protein (muramidase-released protein) of Streptococcus suis type 2.

We cloned and sequenced the gene encoding the muramidase-released protein (MRP) of a pathogenic Streptococcus suis type 2 strain to determine whether its amino acid sequence resembles that of proteins with known functions and to determine its function in virulence. The complete nucleotide sequence composing the gene and the regions flanking it was determined. The deduced amino acid sequence revealed the presence of a signal peptide at the N terminus and a cell envelope anchor at the C terminus, both of which resembled similar regions in several other surface proteins from gram-positive bacteria. The processed form of MRP has a length of 1,209 amino acids and a calculated molecular weight of 131,094. A highly repetitive region preceded the envelope anchor. The repeated units were preceded by a proline-rich stretch of amino acids (26 of 86). No overall homologies were observed between the amino acid sequence of MRP and protein sequences in the EMBL data bank. A particular region within the amino acid sequence, however, showed some similarity with the fibronectin-binding protein of Staphylococcus aureus. Binding of MRP to human fibronectin, however, could not be confirmed.

Amino Acid Sequence↗