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)

Labelling of cell walls or outer membranes from Salmonella typhimurium with ferritin-conjugated antibodies directed against the polysaccharide moiety of the lipopolysaccharide gave the following results: 1. Cell walls or outer membranes from which the mucopeptide had been removed by lysozyme digestion at 0 degrees C carried the label on the outer face of the membrane. 2. When the murein layer was removed by either lysozyme or trypsin at physiological temperature (25-37 degrees C) subsequent labelling showed the lipopolysaccharide to be present on both membrane faces. 3. This reorientation could be achieved by a 1-min treatment of the membranes at 37 degrees C. 4. Glutaraldehyde fixation of the outer membranes did not entirely prevent but somewhat inhibited the temperature-induced reorientation process. 5. The same reorientation phenomenon was observed in lysozyme spheroplasts, which were prepared at 37 degrees C and were subsequently lysed in hypotonic medium at 0 degrees C. These observations are discussed as evidence for a transmembrane movement of lipopolysaccharide, which only takes place in areas where the mucopeptide layer is defective, and only when the temperature is sufficiently high to allow such movement.
 ...
PMID:Asymmetrical distribution and artifactual reorientation of lipopolysaccharide in the outer membrane bilayer of Salmonella typhimurium. 80 74

Using a low temperature resin, we have developed a reliable technique for post-embedding electron immunocytochemistry which is rapid enough to be used in a routine histopathology laboratory. Glutaraldehyde fixed human tissues were dehydrated and embedded at -25 degrees C in a new acrylic resin called LR-Gold. Using the immunogold technique, ultra-thin sections of the tissues were labelled with monoclonal antibodies to cytokeratin, human milk fat globule and HLA-D region antigen; and with polyclonal antisera to lysozyme, kappa and lambda light chains and immunoglobulin M. The resin was easy to section and the preservation of fine structure was excellent. Immunolabelling procedures gave clean and consistent results, and electron micrographs of examples of this are included. It was felt that the preservation of ultrastructure and antigenicity compared well with the results of other workers using low temperature resins such as Lowicryl K4M, but LR-Gold was superior to Lowicryl K4M because sectioning was considerably easier and the sections were more stable in the electron beam.
 ...
PMID:A useful low temperature method for post-embedding electron immunocytochemistry in routine histopathology. 355 11

The postembedding immunoperoxidase staining technique for the localization of immunoglobulins (light and heavy chains) and of lysozyme has been successfully applied to epoxy-embedded human lymph nodes, after removal of the resin. Glutaraldehyde-containing fixatives appear to be suitable for the immunohistochemical localization of human immunoglobulins and lysozyme, provided that the masked antigenicity of these proteins is recovered by proteolytic digestion of the tissue sections using 0.4% pepsin or 0.1% trypsin. Nonglutaraldehyde-containing fixatives allow the immunolocalization of human immunoglobulins without any enzymatic pretreatment. This study shows that tissues routinely fixed in glutaraldehyde and embedded for ultrastructural investigations are actually suitable for immunohistochemical studies on human immunoglobulins and lysozyme.
 ...
PMID:Immunohistochemical localization of human immunoglobulins and lysozyme in epoxy-embedded lymph nodes: effect of different fixatives and of proteolytic digestion. 617 82

Bacillus subtilis spores with altered ionic content were tested for their susceptibility to lysis with lysozyme or sodium nitrite following treatment with glutaraldehyde. The Ca-form was more sensitive to glutaraldehyde (pH 4.0 and pH 7.9) than the untreated or H-form. Removal of spore coat dramatically increased sensitivity of the spore to glutaraldehyde. Pretreatment of spores, the coats of which had been extensively removed, with glutaraldehyde (pH 7.9) reduced the rate of lysis by lysozyme and by sodium nitrite, whereas glutaraldehyde at pH 4.0 had little effect. Glutaraldehyde pretreatment (pH 4.0 and pH 7.9) reduced the amount of hexosamine released by lysozyme but not by nitrite from isolated cortical fragments. Spore protoplasts were more susceptible to 0.01% (w/v) glutaraldehyde at pH 4.0 and isolated spore coats adsorbed alkaline glutaraldehyde more rapidly. These results are discussed in terms of a possible mode of action of glutaraldehyde on the bacterial spore.
 ...
PMID:Interaction of the Bacillus subtilis spore protoplast, cortex, ion-exchange and coatless forms with glutaraldehyde. 642 9

Main and accessory lacrimal tissues from autopsy and biopsy specimens were compared histologically and immunohistologically. Formaldehyde-fixed, paraffin-embedded specimens were studied by light microscopy with hematoxylinand-eosin and PAS staining. Glutaraldehyde-fixed, Epon-embedded specimens were sectioned at 1 micron, stained with alkaline Giemsa, and studied by light microscopy. Specimens fixed in a solution of alcohol and acetic acid were stained by immunofluorescence techniques for lactoferrin, lysozyme, secretory component, and the immunoglobulins IgG, IgA, IgM, IgD, and IgE. The main and the accessory lacrimal tissues were identical histologically and had identical distributions of secretory products and immunoglobulin-containing plasma cells. The finding of myoepithelial cells in 1-micron sections of accessory lacrimal tissue indicates autonomic innervation in that tissue. This finding, in conjunction with the identical immunohistology, indicates a common source for unstimulated and stimulated tears.
 ...
PMID:Histologic and immunohistologic comparison of main and accessory lacrimal tissue. 699 Jul 67

Glutaraldehyde cross-linking followed by separation has been used to detect aggregates of chicken egg-white lysozyme (CEWL) in supersaturated solutions. In solutions of varying NaCl content, the number of aggregates was found to be related to the ionic strength of the solution. Separation by SDS-PAGE showed that percentage of dimer in solution ranged from 25.3% for no NaCl to 27.1% at 15% NaCl, and the aggregates larger than dimer increased from 1.9% for no NaCl to 36.8% at 15% NaCl. Conversely, the percentage of monomers decreased from 72.8% without NaCl to 36.1% at 15% NaCl. Molecular weights by capillary electrophoresis (SDS-CE) were found to be multiples of the monomer molecular weights, with the exception of trimer, which indicates a very compact structure. Native separation was accomplished using size-exclusion chromatography (SEC) and gave a lower monomer concentration and higher aggregate concentration than SDS-CE, which is a denaturing separation method. Most noticeably, trimers were absent in the SEC separation. The number of aggregates did not change with increased time between addition of NaCl and addition of cross-linking agent when separated by gel electrophoresis (SDS-PAGE). The results suggest that high ionic strength CEWL solutions are highly aggregated and that denaturing separation methods disrupt cross-linked products.
 ...
PMID:Supersaturated lysozyme solution structure studied by chemical cross-linking. 1593 Jun 46

Glutaraldehyde has been used for several decades as an effective crosslinking agent for many applications including sample fixation for microscopy, enzyme and cell immobilization, and stabilization of protein crystals. Despite of its common use as a crosslinking agent, the mechanism and chemistry involved in glutaraldehyde crosslinking reaction is not yet fully understood. Here we describe feasibility study and results obtained from a new approach to investigate the process of protein crystals stabilization by glutaraldehyde crosslinking. It involves exposure of a model protein crystal (Lysozyme) to glutaraldehyde in alkaline or acidic pH for different incubation periods and reaction arrest by medium exchange with crystallization medium to remove unbound glutaraldehyde. The crystals were subsequently incubated in diluted buffer affecting dissolution of un-crosslinked crystals. Samples from the resulting solution were subjected to protein composition analysis by gel electrophoresis and mass spectroscopy while crosslinked, dissolution resistant crystals were subjected to high resolution X-ray structural analysis. Data from gel electrophoresis indicated that the crosslinking process starts at specific preferable crosslinking site by lysozyme dimer formation, for both acidic and alkaline pH values. These dimer formations were followed by trimer and tetramer formations leading eventually to dissolution resistant crystals. The crosslinking initiation site and the end products obtained from glutaraldehyde crosslinking in both pH ranges resulted from reactions between lysine residues of neighboring protein molecules and the polymeric form of glutaraldehyde. Reaction rate was much faster at alkaline pH. Different reaction end products, indicating different reaction mechanisms, were identified for crosslinking taking place under alkaline or acidic conditions.
 ...
PMID:Elucidation of the mechanism and end products of glutaraldehyde crosslinking reaction by X-ray structure analysis. 1746 26

The interaction between ZnO nanoparticles (NPs) and lysozyme has been studied using calorimetric as well as spectrophotometric techniques, and interpreted in terms of the three-dimensional structure. The circular dichroism spectroscopic data show an increase in alpha-helical content on interaction with ZnO NPs. Glutaraldehyde cross-linking studies indicate that the monomeric form occurs to a greater extent than the dimer when lysozyme is conjugated with ZnO NPs. The enthalpy-driven binding between lysozyme and ZnO possibly involves the region encompassing the active site in the molecule, which is also the site for the dimer formation in a homologous structure. The enzyme retains high fraction of its native structure with negligible effect on its activity upon attachment to NPs. Compared to the free protein, lysozyme-ZnO conjugates are more stable in the presence of chaotropic agents (guanidine hydrochloride and urea) and also at elevated temperatures. The possible site of binding of NP to lysozyme has been proposed to explain these observations. The stability and the retention of a higher level of activity in the presence of the denaturing agent of the NP-conjugated protein may find useful applications in biotechnology ranging from diagnostic to drug delivery.
 ...
PMID:Structure and activity of lysozyme on binding to ZnO nanoparticles. 2000 Jul 58