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PubMed1975

Serum lysozyme in Crohn's disease and ulcerative colitis.

Serum lysozyme (muramidase) concentrations were determined in patients with different types of inflammatory bowel disease and in normal subjects. The mean (plus or minus S.E.M.) lysozyme concentration for each group was as follows: controls, 8.8 plus or minus 0.3, ulcerative colitis, 9.3 plus or minus 0.6, Crohn's disease, 26.3 plus or minus 1.4. a and bacterial and nonbacterial enteritis, 8.9 plus or minus 0.7 mug per milliliter. Thus, mean enzyme levels were significantly greater in Crohn's disease than in ulcerative colitis (p smaller than 0.001), bacterial and nonbacterial enteritis (p smaller than 0.001) and healthy volunteers (p smaller than 0.001). The elevation of serum lysozyme in Crohn's disease may be related to tissue macrophages because no correlation was found between either the serum lysozyme concentration and the white-cell counts or the absolute numbers of circulating granulocytes or monocytes. Our findings suggest that serum lysozyme may be useful in the differential diagnosis of Crohn's disease from other types of bowel inflammation.

Adolescent↗
PubMed1988

Covalent modification of the beta-1,4-N-acetylmuramoylhydrolase of Streptococcus faecium with 5-mercaptouridine monophosphate.

Purified beta-1,4-N-acetylmuramoylhydrolase (muramidase-1; EC 3.2.1.17) of Streptococcus faecium ATCC 9790 has been shown to be covalently substituted with approximately 12 mol equivalents of monomeric 5-mercaptouridine monophosphate. All 12 residues are present on the proteolytically processed 87-kDa active form of the enzyme. A peptide fragment containing 5-mercaptouridine, tyrosine, alanine, glycine, and leucine was isolated consistent with an O-phosphate linkage of the nucleotide to tyrosine.

Mass Spectrometry↗
PubMed1995

A Ca(2+)-binding chimera of human lysozyme and bovine alpha-lactalbumin that can form a molten globule.

In contrast to lysozymes, which undergo two-state thermal denaturation, the Ca(2+)-free form of the homologous alpha-lactalbumins forms an intermediate "molten globule" state. To understand this difference, we have produced a chimera of human lysozyme and bovine alpha-lactalbumin. In the synthetic gene of the former the sequence coding for amino acid residues 76-102 was replaced by that for bovine alpha-lactalbumin 72-97, which represents the Ca(2+)-binding loop and the central helix C. The chimeric protein, LYLA1, expressed in Saccharomyces cerevisiae was homogeneous on electrophoresis and mass spectrometry. Its Ca2+ binding constant was 2.50 (+/- 0.04) x 10(8) M-1, and its muramidase activity 10% of that of human lysozyme. One-dimensional NMR spectroscopy indicated the presence of a compact, well structured protein. From two-dimensional NMR spectra, main chain resonances for 118 of a total of 129 residues could be readily assigned. Nuclear Overhauser effect analysis and hydrogen-deuterium exchange measurements indicated the presence and persistence of all expected secondary structure elements. Thermal denaturation, measured by circular dichroism, showed a single transition temperature for the Ca2+ form at 90 degrees C, whereas unfolding of the apo form occurred at 73 degrees C in the near-UV and 81 degrees C in the far-UV range. These observations illustrate that by transplanting the central part of bovine alpha-lactalbumin, we have introduced into human lysozyme two important properties of alpha-lactalbumins, i.e. stabilization through Ca2+ binding and molten globule behavior.

Amino Acid Sequence↗
PubMed1999

Inactivated pbp4 in highly glycopeptide-resistant laboratory mutants of Staphylococcus aureus.

Both vancomycin- and teicoplanin-resistant laboratory mutants of Staphylococcus aureus produce peptidoglycans of altered composition in which the proportion of highly cross-linked muropeptide species is drastically reduced with a parallel increase in the representation of muropeptide monomers and dimers (Sieradzki, K., and Tomasz, A. (1997) J. Bacteriol. 179, 2557-2566; and Sieradzki, K. , and Tomasz, A. (1998) Microb. Drug Resist. 4, 159-168). We now report that the distorted peptidoglycan composition is related to defects in penicillin-binding protein 4 (PBP4); no PBP4 was detectable by the fluorographic assay in membrane preparations from the mutants, and comparison of the sequence of pbp4 amplified from the mutants indicated disruption of the gene by two types of abnormalities, a 17-amino acid long duplication starting at position 305 of the pbp4 gene was detected in the vancomycin-resistant mutant, and a stop codon was found to be introduced into the pbp4 KTG motif at position 261 in the mutant selected for teicoplanin resistance. Additional common patterns of disturbances in the peptidoglycan metabolism of the mutants are indicated by the increased sensitivity of mutant cell walls to the M1 muramidase and decreased sensitivity to lysostaphin, which is a reversal of the susceptibility pattern of the parental cell walls. Furthermore, the results of high performance liquid chromatography analysis of lysostaphin digests of peptidoglycan suggest an increase in the average chain length of the glycan strands in the peptidoglycan of the glycopeptide-resistant mutants. The increased molar proportion of muropeptide monomers in the cell wall of the glycopeptide-resistant mutants should provide binding sites for the "capture" of vancomycin and teicoplanin molecules, which may be part of the mechanism of glycopeptide resistance in S. aureus.

Amino Acid Sequence↗
PubMed2000

The pgdA gene encodes for a peptidoglycan N-acetylglucosamine deacetylase in Streptococcus pneumoniae.

Analytical work on the fractionation of the glycan strands of Streptococcus pneumoniae cell wall has led to the observation that an unusually high proportion of hexosamine units (over 80% of the glucosamine and 10% of the muramic acid residues) was not N-acetylated, explaining the resistance of the peptidoglycan to the hydrolytic action of lysozyme, a muramidase that cleaves in the glycan backbone. A gene, pgdA, was identified as encoding for the peptidoglycan N-acetylglucosamine deacetylase A with amino acid sequence similarity to fungal chitin deacetylases and rhizobial NodB chitooligosaccharide deacetylases. Pneumococci in which pgdA was inactivated by insertion duplication mutagenesis produced fully N-acetylated glycan and became hypersensitive to exogenous lysozyme in the stationary phase of growth. The pgdA gene may contribute to pneumococcal virulence by providing protection against host lysozyme, which is known to accumulate in high concentrations at infection sites.

Acetylation↗
PubMedDate not supplied

Inflammatory fibroid polyp of the small intestine: ultrastructural and immunohistochemical observations.

The ultrastructural and immunohistochemical features of a primary tumor of the ileum showing the classic histologic features of an inflammatory fibroid polyp (IFP) of the gastrointestinal tract are presented. Ultrastructurally the proliferating cells showed a combination of fibroblastic and histiocytic features, with abundant rough endoplasmic reticulum and active production of collagen in many of the cells and long, dendritic cytoplasmic projections with large cytoplasmic vacuoles containing remnants of phagocytosed cellular debris in others. Immunohistochemical studies showed strong cytoplasmic positivity in the proliferating cells with vimentin antibodies and scattered positivity with muramidase. Additional findings include the ultrastructural demonstration of oligocilia and occasional primitive intercellular junctions. The findings in this case suggest that IFP may represent a proliferation of primitive submucosal stromal cells exhibiting incomplete fibrohistiocytic differentiation.

Aged↗
PubMed1977

Simultaneous demonstration of peroxidase and lysozyme activities in leukemic cells.

A simple cytochemical and cytobacterial method for the simultaneous demonstration of peroxidase and lysozyme (muramidase) activities in individual cells was devised. In characterization of myeloid and monocyte series, the combination of these myeloid- and monocyte-specific enzymes not only was more informative than a single enzyme but made it easier to differentiate acute myelomonocytic leukemia, with higher lysozyme activity, from acute myeloid leukemia, with higher peroxidase activity. Acute lymphocytic leukemia had no lysozyme or peroxidase activity.

Bone Marrow↗
PubMed1981

Immunohistochemical identification of lysozyme in cutaneous lesions of alleged histiocytic nature.

Histiocytosis X, multicentric reticulohistiocytosis, juvenile xanthogranuloma, the "fibrous" type of dermatofibroma, dermatofibrosarcoma protuberans, and malignant fibrous histiocytoma are all characterized by dermal and/or subcutaneous infiltrates composed at least partially of cells having morphologic features suggestive of histiocytes. Paraffin-embedded tissues representing these conditions were stained for lysozyme (muramidase) with a peroxidase-antiperoxidase technic. The cells of juvenile xanthogranuloma were rich in lysozyme. Some of the cells of histiocytosis X showed a positive pattern, and the cells of the other three conditions were essentially negative. This study confirmed the histiocytic nature of juvenile xanthogranuloma and multicentric reticulohistiocytosis, supported the interpretation that there is a histiocytic component in the lesions of histiocytosis X, and cast some doubt on the alleged histiocytic nature of "fibrous" dermatofibroma, dermatofibrosarcoma protuberans, and malignant fibrous histiocytoma.

Fibroma↗
PubMed1979

Furosemide enhancement of experimental gentamicin nephrotoxicity: comparison of functional and morphological changes with activities of urinary enzymes.

Dogs were given gentamicin (10 mg/kg) intramuscularly every 8 hr for 10 days. Levels of serum creatinine rose by day 6 (0.91 +/- 0.08 vs. 0.75 +/- 0.02 mg/dl for controls, P less than 0.05) and of blood urea nitrogen by day 8 (24.3 +/- 4.80 vs. 16.1 +/- 0.90 mg/dl for controls, P less than 0.05). Gentamicin nephrotoxicity occurred earlier and was more marked when furosemide (2 mg/kg) was added: the level of serum creatinine by day 6 was 1.62 +/- 0.25 mg/dl (P less than 0.05), and the level of blood urea nitrogen by day 8 was 181 +/- 23.5 mg/dl (P less than 0.01). Elevations in the activities of the urinary enzymes beta-glucuronidase, N-acetyl-beta-glucosaminidase, and muramidase preceded rises in levels of serum creatinine and blood urea nitrogen. Examination of serial percutaneous renal biopsy specimens showed that gentamicin administration was associated with hyaline droplet degeneration, lysosomal changes, and, later, cell necrosis (primarily of the proximal tubules). Changes in renal morphology were more severe and occurred earlier when furosemide was administered concomitantly. In summary, furosemide enhanced gentamicin nephrotoxicity. Enzymuria was an early sign of gentamicin nephrotoxicity.

Acetylglucosaminidase↗
PubMed1978

Purification and characterization of lysozyme produced by Streptomyces erythraeus.

A species of lysozyme (SE lysozyme) was purified from culture filtrate of Streptomyces erythraeus. The enzyme has a molecular weight of 18,500 as determined by ultracentrifugation. Its isoelectric point is 9.5, and it shows optimal activity at pH 4.0 with an optimal ionic strength of 0.1. Investigation of the substrate specificity showed SE lysozyme to be an N-acetyl-muramidase. The simplest product in the digest of cell walls of Micrococcus lysodeikticus was identified as a disaccharide, [GlcNAcbeta(1 leads to 4) MurNAc]. While S. aureus as well as M. lysodeikticus was lysed by this lysozyme, chitin and its derivatives were not.

Amino Acid Sequence↗
PubMed1987

Immunohistochemical demonstration of alpha-1-antitrypsin and alpha-1-antichymotrypsin in normal human endometrium.

Forty-five specimens of endometrium, consisting of 10 proliferative, 10 each of early, mid-, and late secretory, and five menstrual phase, were examined with antibodies to alpha-1-antitrypsin (A1AT), alpha-1-antichymotrypsin (A1ACT), muramidase, and serum 22, using an indirect peroxidase-antiperoxidase immunoperoxidase technique. Five postmenopausal and 10 pregnancy endometria were also examined. Very few macrophages were detected. Other stromal cells, however, in premenopausal, nonpregnant endometrium, stained strongly for A1AT and A1ACT but not with the other two antisera. Stromal cells following the menopause did not stain nor did the decidual cells of pregnancy. Only rare, isolated epithelial cells or whole glands stained for A1AT and A1ACT. The function of these antiproteases in endometrium may be to regulate the protease activity of the implanting blastocyst or the immunological response to it.

Antibodies↗
PubMed1993

Multinucleated stromal giant cells of the uterine cervix.

A prospective clinicopathological study including 100 consecutive hysterectomies and 100 consecutive cone specimens to investigate the frequency and pathogenesis of multinucleated stromal giant cells (SGCs) in the uterine cervix is presented. Sections containing SGCs were analyzed by immunohistochemical methods for the presence of cytokeratin, S-100 protein, factor VIII, desmin, muramidase, alpha 1-antichymotrypsin, and vimentin. Tissue for electron microscopy was punched out of four paraffin blocks from four different cases. SGCs were not found in patients < 30 years old, but their incidence increased with age until the sixth decade, at which time they were found in 42% of patients. We found at the same time that the incidence of SGCs declines in the seventh decade. SGCs were not related to any inflammatory or granulomatous lesion, and their presence was independent of other clinical parameters, such as hormonal therapy, history of trauma on the uterine cervix, pregnancy, or parity in general. Immunohistochemical and ultrastructural analyses support the concept of a fibroblastic-histiocytic origin of SGCs. SGCs in the uterine cervix may reflect a physiological tissue reaction during the transition from the fertile to the postmenopausal state.

Adult↗
PubMed1985

The peptidoglycan of Neisseria gonorrhoeae, with or without O-acetyl groups, contains anhydro-muramyl residues.

Muramidase digests of alkali-treated SDS-insoluble peptidoglycan from two strains of Neisseria gonorrhoeae were examined. Both strains contained disaccharide peptide monomers that had intramolecular 1,6-anhydro-muramyl ends. In contrast to strain 1L260, in which 50% of the monomer fraction is O-acetylated, the monomer fraction from strain RD5 was completely devoid of O-acetyl groups, as shown by HPLC. Penicillin decreased the O-acetylation of peptidoglycan but did not affect the proportion of anhydro-muramyl residues.

Acetylation↗
PubMed1986

Normal pole formation during total inhibition of wall synthesis of Bacillus subtilis.

Previous work has shown that the side wall of a Gram-positive rod is initially laid down as a compact layer inside the older wall. It is then stretched as it comes to bear tension due to the osmotic pressure inside the cell. If the polar wall is likewise capable of a degree of expansion, then no new murein need be added while the planar cross-wall splits and converts into two poles. In Bacillus subtilis mutant strain FJ6, which is deficient in autolytic enzymes, pole formation can be caused by addition of exogenous muramidase (10 micrograms hen egg white lysozyme ml-1 for 10 min at 35 degrees C). This strain grows as long filaments with many completed cross-walls, but enzymic treatment caused the formation of many new poles of normal morphology as judged by thin section electron microscopy. Fully separated poles of normal appearance were also found when more than 100 times the MIC (1 microgram ml-1) of vancomycin was added to block wall growth totally and rapidly 10 min before the addition of lysozyme. We conclude, therefore, that no new murein is needed in the conversion of the flat septum into poles and that the unstressed cross-wall is capable of the necessary expansion.

Bacillus subtilis↗
PubMed1993

Cell wall assembly in Staphylococcus aureus: proposed absence of secondary crosslinking reactions.

The distribution of muropeptides formed by muramidase digestion of peptidoglycan from Staphylococcus aureus H was determined by gel-filtration HPLC. The observed crosslinking pattern supports the conclusion that incorporation of peptidoglycan in S. aureus proceeds by a similar mechanism to that proposed earlier for Bacillus megaterium. In this mechanism single glycan-peptide strands are incorporated into the sacculus by crosslinking reactions that take place only between the monomer muropeptide units of the incoming glycopeptide and muropeptides present in the innermost region of wall at the wall-membrane interface: such crosslinking reactions take place only during incorporation and no other crosslinking reactions occur. This assembly process has now been termed restricted monomer addition. The present analysis shows that the distribution of muropeptides in S. aureus peptidoglycan is in excellent agreement with that predicted by this mechanism. We propose that cell wall assembly in S. aureus proceeds via restricted monomer addition without any requirement for the secondary crosslinking reactions that have been suggested to occur in this organism. The high degree of crosslinking in S. aureus, 80% in this study, may result mainly from the freedom for crosslinking provided by the pentaglycine bridge peptide.

Cell Wall↗
PubMed1999

Inhibition of growth and secreted aspartyl proteinase production in Candida albicans by lysozyme.

Lysozyme (muramidase) is a non-specific, antimicrobial protein ubiquitous in human mucosal secretions such as saliva. Although its antibacterial and antifungal activities are well recognised, there are no data on the specific concentrations necessary to affect the growth of Candida albicans or about the effect of lysozyme on the production of secreted aspartyl proteinase (Sap), a putative virulence factor of C. albicans. Five Sap-producing isolates of C. albicans were cultured in YCB-BSA medium with various concentrations of lysozyme to examine its effect on yeast cell growth, ultrastructural cellular topography and extracellular and intracellular Sap concentration and activity. Lysozyme was candidacidal at high concentrations and decreased significantly the extracellular Sap concentration at sublethal doses, accompanied by intracellular accumulation of the enzyme. At low concentrations of lysozyme (c. 10 microg/ml), Sap activity decreased more than two-fold and Sap concentration decreased five-fold without any appreciable effect on cell growth or viability. Ultrastructural investigations showed ballooned cells and cells with invaginations (especially present near bud scars), indicating that cell-wall components may be possible targets for this enzyme. All concentrations of lysozyme tested were well within physiologically attainable levels. These data suggest that lysozyme has, at least, a bimodal action on C. albicans, killing the organism at higher concentrations and modulating Sap metabolism at lower concentrations.

Anti-Infective Agents↗
PubMed2005

Peptidoglycan degradation by specialized lytic transglycosylases associated with type III and type IV secretion systems.

Specialized lytic transglycosylases are muramidases capable of locally degrading the peptidoglycan meshwork of Gram-negative bacteria. Specialized lytic transglycosylase genes are present in clusters encoding diverse macromolecular transport systems. This paper reports the analysis of selected members of the specialized lytic transglycosylase family from type III and type IV secretion systems. These proteins were analysed in vivo by assaying their ability to complement the DNA transfer defect of the conjugative F-like plasmid R1-16 lacking a functional P19 protein, the specialized lytic transglycosylase of this type IV secretion system. Heterologous complementation was accomplished using IpgF from the plasmid-encoded type III secretion system of Shigella sonnei and TrbN from the type IV secretion system of the conjugative plasmid RP4. In contrast, neither VirB1 proteins (Agrobacterium tumefaciens, Brucella suis) nor IagB (Salmonella enterica) could functionally replace P19. In vitro, IpgF, IagB, both VirB1 proteins, HP0523 (Helicobacter pylori) and P19 displayed peptidoglycanase activity in zymogram analyses. Using an established test system and a newly developed assay it was shown that IpgF degraded peptidoglycan in solution. IpgF was active only after removal of the chaperonin GroEL, which co-purified with IpgF and inhibited its enzymic activity. A mutant IpgF protein in which the predicted catalytic amino acid, Glu42, was replaced by Gln, was completely inactive. IpgF-catalysed peptidoglycan degradation was optimal at pH 6 and was inhibited by the lytic transglycosylase inhibitors hexa-N-acetylchitohexaose and bulgecin A.

Bacterial Proteins↗
PubMed1990

Peptidoglycan cross-linking in Staphylococcus aureus. An apparent random polymerisation process.

The peptidoglycan of Staphylococcus aureus contains relatively short glycan chains and is highly cross-linked via its peptide chains. The material from wild-type (strain H) and mutants H28, H4B and MR-1 was freed from the teichoic-acid-linked component and then hydrolysed by Chalaropsis muramidase to yield disaccharide-repeating units of the glycan with attached peptides either non-cross-linked (monomer) or joined to similar units by one (dimer), two (trimer) or more (oligomer) peptide cross links. The resulting fragments were separated by high-resolution HPLC so that distinguishable components as large as nonamer could be identified. Extrapolation showed that, in S. aureus H, H28 and MR-1, oligomers at least as large as eicosamer formed part of the smooth distribution of oligomer fragments, whereas in strain H4B (PBP4-) the maximum size was around dodecamer. The oligomer distribution profile was related to the polymerization theories of Flory, which allow a distinction to be made between a monomer addition model, whereby each oligomer can only be synthesized by the addition of a single monomer unit to its next lower homologue, and a random addition model, in which an oligomer can be formed by linkage of any combination of its constituent smaller units. In S. aureus close approximation to the random addition model for oligomer synthesis and hence for peptidoglycan cross-linking was observed, both in PBP4+ and PBP4- mutants. The implications for secondary cross-linking in S. aureus cell wall formation are inescapable, although the possibility of an endopeptidase/transpeptidase providing later modification of the peptidoglycan is not completely ruled out.

Binding Sites↗