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

The length distribution of the glycan strands in the murein (peptidoglycan) sacculus of Escherichia coli has been analyzed after solubilization of the murein by complete digestion with human serum amidase. The glycan strands released were separated according to length by reversed-phase HPLC on wide-pore Nucleosil 300 C18 material at 50 degrees C, employing a convex gradient from 5 to 11% acetonitrile. The length of the fractionated glycan strands, which carry a nonreducing 1,6-anhydromuramic acid as a natural end group, was calculated from the ratio of total to nonreducing terminal muramic acid residues. This was possible after complete hydrolysis of the isolated glycan strands by muramidase followed by separation of the released nonreducing and reducing di- and tetrasaccharides by reversed-phase HPLC on Hypersil C18. The method established allows the separation of the glycan strands of murein, a poly-GlcNAc(beta 1-4)MurNAc-polysaccharide, up to a degree of polymerization of approximately 60. The predominant lengths of the glycan strands were 5 to 10 GlcNAc(beta 1-4)MurNAc disaccharide units.
 ...
PMID:Isolation and separation of the glycan strands from murein of Escherichia coli by reversed-phase high-performance liquid chromatography. 228 38

Macromolecular adsorption is known to occur as a complex process, often in a series of steps. Several models are discussed in the literature which describe the microscopic structure of the adsorbate. In the present study we investigated the adsorption of hen egg white lysozyme on alkylated silicon oxide surfaces. A combination of fluorescence excitation in the evanescent field and fluorescence recovery after photobleaching allowed us to measure the amount of adsorbed fluorescent lysozyme and the equilibrium exchange kinetics with molecules in solution. We found that a model with at least three classes of adsorbed molecules is necessary to describe the experimental results. A first layer is formed by the molecules which adsorb within a short time after the beginning of the incubation. These molecules make up approximately 65% of the final coverage. They are quasi-irreversibly adsorbed and do not measurably exchange with bulk molecules within one day even at temperatures up to 55 degrees C. A second layer, which reaches equilibrium only after several hours of incubation, shows a pronounced exchange with bulk molecules. The on-off kinetics show a distinct temperature dependence from which an activation barrier of delta E approximately 22 kcal/mol is derived. A third layer of molecules that exchange rapidly with the bulk can be seen to comprise approximately 10% of the total coverage. The exchange rate is on the order of fractions of a second. The binding of the latter two classes of adsorbed molecules is exothermic. From the temperature dependence of the coverage, the binding enthalpy of the slowly exchanging layer was estimated to be delta Hads approximately 3.8 kcal/mol. The second and third class of molecules remain enzymatically active as a muramidase, which was tested by the lysis of the cell walls of Micrococcus lysodeiktikus. The molecules in the first layer, on the other hand, showed no enzymatic activity.
 ...
PMID:Multilayer adsorption of lysozyme on a hydrophobic substrate. 230 2

The nucleotide sequences of genes cpl7 and cpl9 of the Streptococcus pneumoniae bacteriophages Cp-7 and Cp-9, encoding the muramidases CPL-7 and CPL-9, respectively, have been determined. The N-terminal domains of CPL-7 and CPL-9 were virtually identical to that previously reported for the CPL-1 muramidase. The C-terminal domain of the CPL-7 muramidase, however, was different from those of the host amidase and the phage Cp-1 and Cp-9 lysozymes. Whereas all enzymes studied are characterized by repeated sequences at their C termini, the repeat-unit lengths are 20 amino acids (aa) in CPL-1, CPL-9 and in the host amidase, but 48 aa in CPL-7. Six repeated sequences represent the C-terminal domains of CPL-1, CPL-9 and the host amidase, and 2.8 perfect tandem repetitions that of CPL-7. The peculiar characteristics of the structure of CPL-7 muramidase correlate with its biochemical and biological properties. Whereas CPL-1, CPL-9 and the pneumococcal amidase strictly depend on the presence of choline-containing cell walls for activity, CPL-7 is able to degrade cell walls containing either choline or ethanolamine. These results support the previously postulated role for the C-terminal domain of these lytic enzymes in substrate recognition and provide further experimental evidence supporting the notion that the proteins have evolved by an exchange of modular units.
 ...
PMID:Modular organization of the lytic enzymes of Streptococcus pneumoniae and its bacteriophages. 231 37

DD-Carboxypeptidase (DD-CPase) activity of Enterococcus hirae (Streptococcus faecium) ATCC 9790 was extracted from intact bacteria and from the insoluble residue (crude cell wall fraction) of mechanically disrupted bacteria by a brief treatment at pH 10.0 (10 mM glycine-NaOH) at 0 degrees C or by extraction with any of several detergents. Extractions with high salt concentrations failed to remove DD-CPase activity from the crude wall fraction. In contrast to N-acetylmuramoylhydrolase (both muramidase 2 and muramidase 1) activities, DD-CPase activity failed to bind to insoluble cell walls or peptidoglycan matrices. Thus, whereas muramidase 1 and muramidase 2 activities can be considered to be cell wall proteins, the bulk of the data are consistent with the interpretation that the DD-CPase of this species is a membrane protein that is sometimes found in the cell wall fraction, presumably because of hydrophobic interactions with other proteins and cell wall polymers. The binding of [14C]penicillin to penicillin-binding protein 6 (43 kilodaltons) was proportional to DD-CPase activity. Kinetic parameters were also consistent with the presence of only one DD-CPase (penicillin-binding protein 6) in E. hirae.
 ...
PMID:Properties of cell wall-associated DD-carboxypeptidase of Enterococcus hirae (Streptococcus faecium) ATCC 9790 extracted with alkali. 236 45

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.
 ...
PMID:Peptidoglycan cross-linking in Staphylococcus aureus. An apparent random polymerisation process. 238 86

Twenty patients with clinically and microscopically confirmed lichen planus were studied immunohistochemically. Monoclonal antibody to HLA-DR antigens and polyclonal antisera to S-100 protein and muramidase were applied to paraffin-embedded sections for the purpose of elaborating on the pathogenesis of this disease. Trypsin incubation of sections was also done in order to determine its effect on immunostaining. Langerhans cells were identified with anti-S-100 and anti-HLA-DR, and macrophages were identified with antimuramidase and anti-HLA-DR. Keratinocytes also expressed HLA-DR membrane activity in lichen planus tissue. Trypsinization significantly improved the expression of S-100 protein and muramidase antigens. It was concluded that Langerhans cells, macrophages, and keratinocytes play important roles in antigen processing and/or phagocytosis during the natural history of this disease.
 ...
PMID:Immunohistochemical staining of Langerhans cells and macrophages in oral lichen planus. 241 7

Recent evidence suggests that the proliferative cells of idiopathic histiocytosis may be derived from Langerhans cells. In this study, antisera to S-100 protein, HLA-DR (la-like) antigen, muramidase, and alpha 1-antichymotrypsin were tested on formalin-fixed, paraffin-embedded tissue from nine cases of idiopathic histiocytosis using an immunoperoxidase technique. Tumor cells were positive for S-100 protein and HLA-DR antigen but negative for muramidase and alpha 1-antichymotrypsin. Mononuclear phagocytes were positive for HLA-DR antigen, muramidase, and alpha 1-antichymotrypsin but negative for S-100 protein. The immunohistochemical staining pattern of the tumor cells in these cases of idiopathic histiocytosis is similar to that seen for normal Langerhans cells. When these results are coupled with electron microscopic and histochemical data, it would appear that the origin of cells in idiopathic histiocytosis is from the Langerhans cell or its precursor. Thus, this condition might be better designated "Langerhans cell disease."
 ...
PMID:Immunohistochemical study of idiopathic histiocytosis of the mandible and maxilla. 241 99

Paraffin sections of formaldehyde-fixed renal biopsies were labeled for complement C3 by a polyclonal rabbit antibody to human complement C3, by the peroxidase-antiperoxidase complex (PAP) and the avidin-biotin peroxidase complex (ABC) techniques, respectively. All tissues had C3 deposits according to direct immunofluorescence on fresh frozen sections. Staining for muramidase was introduced as an intrinsic control for the degree of tissue proteolysis after the necessary trypsin digestion prior to the immunoenzyme labeling. The results indicated that even minute deposits of C3 could be detected in paraffin sections by the ABC method, which was more sensitive than the PAP technique; the ABC method allowed a maximal dilution of 1:2,400 of the primary antibody as compared to 1:800 for the PAP technique.
 ...
PMID:Conditions for the immunohistochemical demonstration of complement factor C3 in formaldehyde-fixed and paraffin-embedded renal tissues. 242 Jul 64

2 low-molecular cysteine-proteinase inhibitors were purified from human tonsillar tissues: an acid cysteine proteinase inhibitor (ACPI), and a neutral cysteine proteinase inhibitor (NCPI). Their biochemical and immunological characteristics appeared to be identical to those inhibitors which we have identified in other human tissues in previous studies (epidermis and spleen). An immunohistological analysis revealed in tonsillar squamous epithelium a strong and consistent immunoreactivity for both inhibitors. In the tonsillar lymphatic tissue, ACPI-immunoreactivity appeared to be a characteristic mainly of dendritic reticulum cells whereas a prominent NCPI-immunoreactivity was confined mostly for the histiocytic reticulum cells in lymphoid secondary follicles. We also compared the distribution of the 2 immunoreactive inhibitors with the immunohistology as revealed by antisera raised against keratin and muramidase. Limitations of the immunohistochemistry of cysteine proteinase inhibitors are discussed in the light of an extensive trial of various fixation procedures. We deem that proposal of Barrett (1984) for the nomenclature of cysteine proteinase inhibitors is appropriate. According to it the ACPI is the cystatin A, and the NCPI is the cystatin B.
 ...
PMID:[Low-molecular cysteine protease inhibitors in the human palatal tonsil]. 242 40

Seven cardiac myxomas were studied by immunoperoxidase and immunofluorescence in formalin fixed and paraffin embedded tissues. Specific antisera to factor VIII related antigens, vimentin, myosin of smooth muscle, actin, desmin, alpha-1-antitrypsin, muramidase, fibrin and prekeratin antigens were used. All myxoma cells reacted positively with antibodies to vimentin and showed no staining reaction with antibodies to alpha-1-antitrypsin, muramidase, myosin, or prekeratin. Factor VIII related antigen was found only in endothelial cells and not in myxoma cells proper. Fibrin was found in patchy areas within the stroma. Antisera to actin and desmin failed to react with formalin fixed tissue. Our results suggest that the main cellular component of cardiac myxoma is a primitive mesenchymal cell without immunohistochemical evidence of more specific differentiation.
 ...
PMID:Cardiac myxoma. A retrospective immunohistochemical study. 243 71


<< Previous 1 2 3 4 5 6 7 8 9 10