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)

Legionella pneumophila and related species were examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis for outer membrane proteins. Of the 10 species examined, 9 contained a 24-kilodalton (kDa) major outer membrane protein (MOMP) that was resolvable only when outer membrane material was heated in the presence of 2-mercaptoethanol. Labeling studies with [35S]cysteine indicated that the protein contained cysteine, and disulfide cross-linking of the unreduced complex was demonstrated by labeling with iodoacetamide. The unreduced outer membrane preparation contained peptidoglycan, and after treatment with lysozyme to remove peptidoglycan, a protein complex of 95 kDa was observed by sodium dodecyl sulfate polyacrylamide gel electrophoresis in the absence of 2-mercaptoethanol. Reduction of the 95-kDa complex yielded 24-kDa monomers, suggesting that the 95-kDa complex was composed of four subunits. The 24-kDa MOMP from L. pneumophila was purified, and antibody produced to this protein cross-reacted with all species of Legionella as determined from an immunoblot of a sodium dodecyl sulfate gel. Only serogroup 1 strains of L. bozemanii lacked the 24-kDa MOMP and showed no cross-reactivity. These results suggest that the 24-kDa MOMP common to most species of Legionella contains a genus-specific epitope.
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PMID:Disulfide-bonded outer membrane proteins in the genus Legionella. 398 79

Membranes were isolated from Bacillus stearothermophilus 2184D by lysozyme digestion of the cell wall and subsequent differential centrifugation. Observations with the electron microscope indicate that such membranes are relatively intact and have a typical membrane appearance. Nitrate will preferentially oxidize the cytochrome b of such membranes. Approximately 80% of the total respiratory nitrate reductase activity of whole cells can be localized in the washed membrane fraction and the process of membrane isolation results in a sixfold purification of this enzyme. Of several detergents tested, sodium dodecyl sulfate, Triton 114, and Triton X-100 are most effective in converting reduced methyl viologen-nitrate reductase to a form which will not pellet at 130,000 x g. Density gradient analysis reveals that such detergent-mediated solubilization converts virtually all membrane protein to a form of lighter density.
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PMID:Localization and solubilization of the respiratory nitrate reductase of Bacillus stearothermophilus. 433 9

Two techniques were used to isolate outer membrane proteins from Campylobacter jejuni, EDTA-lysozyme extraction and sodium-N-lauroylsarcosinate (Sarkosyl) solubilization. The protein profiles of the two preparations were similar, with a few additional bands in the EDTA-lysozyme preparations. The major outer membrane protein was 43,000 (43K) daltons, and there were 8 to 10 minor bands ranging from 92K to 14K daltons. There was no difference in the protein profile of a strain causing an infection (strain 17) and the resulting stool isolate (strain 17J). Sera collected before the infection and during the acute and convalescent stages were used with Western blotting and immunoautoradiographic techniques to determine the antigenicity of outer membrane proteins. A number of antigenic proteins were detected before the infection by their reaction with preinfection serum (61K, 51K, 43K, 40K, 34K, and 31K daltons), and three additional bands appeared during the infection when acute and convalescent sera were used (92K, 56K, and 19K daltons). Furthermore, an area of the gel at less than 14.4K daltons that did not stain with Coomassie brilliant blue became visible in the immune blots when the convalescent serum was used.
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PMID:Human antibody response to outer membrane proteins of Campylobacter jejuni during infection. 619 86

A sensitive hapten-sandwich immunofluorescence technique was used to examine binding of lipopolysaccharide (LPS) at the single-cell level. The structural features governing such binding to murine lymphocytes were investigated by evaluating LPS binding in the presence of a variety of charged molecules and after different target-cell treatments. Polymyxin B, the positively charged proteins egg-white lysozyme and protamine chloride, and the polyanion dextran sulfate inhibited LPS binding to murine lymphocytes. Pretreatment with the proteolytic enzyme pronase and the cross-linking agent paraformaldehyde abolished the capacity of lymphocytes to bind LPS. Inhibition by polymyxin B was less effective when added 30 min after initiation of incubation of LPS with cells at 0 C or when added at the initiation of incubation at 37 C. These results suggest that the interaction between LPS and lymphocytes is a two-stage process, the first of which is dependent on a positively charged membrane protein. The second stage is postulated to be an irreversible hydrophobic interaction between LPS and membrane lipids.
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PMID:Structural features of binding of lipopolysaccharides to murine lymphocytes. 620 43

Partly autolyzed, osmotically stabilized cells of Bacillus subtilis W23 synthesized peptidoglycan from the exogenously supplied nucleotide precursors UDP-N-acetylglucosamine and UDP-N-acetylmuramyl pentapeptide. Freshly harvested cells did not synthesize peptidoglycan. The peptidoglycan formed was entirely hydrolyzed by N-acetylmuramoylhydrolase, and its synthesis was inhibited by the antibiotics bacitracin, vancomycin, and tunicamycin. Peptidoglycan formation was optimal at 37 degrees C and pH 8.5, and the specific activity of 7.0 nmol of N-acetylglucosamine incorporated per mg of membrane protein per h at pH 7.5 was probably decreased by the action of endogenous wall autolysins. No cross-linked peptidoglycan was formed. In addition, a lysozyme-resistant polymer was also formed from UDP-N-acetylglucosamine alone. Peptidoglycan synthesis was inhibited by trypsin and p-chloromercuribenzenesulfonic acid, and we conclude that it occurred at the outer surface of the membrane. Although phospho-N-acetylmuramyl pentapeptide translocase activity was detected on the outside surface of the membrane, no transphosphorylation mechanism was observed for the translocation of UDP-N-acetylglucosamine. Peptidoglycan was similarly formed with partly autolyzed preparations of B. subtilis NCIB 3610, B. subtilis 168, B. megaterium KM, and B. licheniformis ATCC 9945. Intact protoplasts of B. subtilis W23 did not synthesize peptidoglycan from externally supplied nucleotides although the lipid intermediate was formed which was inhibited by tunicamycin and bacitracin. It was therefore considered that the lipid cycle had been completed, and the absence of peptidoglycan synthesis was believed to be due to the presence of lysozyme adhering to the protoplast membrane. The significance of these results and similar observations for teichoic acid synthesis (Bertram et al., J. Bacteriol. 148:406-412, 1981) is discussed in relation to the translocation of bacterial cell wall polymers.
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PMID:Peptidoglycan synthesis by partly autolyzed cells of Bacillus subtilis W23. 630 81

Filtered proteins including the low-molecular-weight protein lysozyme are reabsorbed by the proximal tubule via adsorptive endocytosis. This process starts with binding of the protein to the brush-border membrane. The binding of 125I-labelled egg-white lysozyme (EC 3.2.1.17) to isolated brush-border membranes of rat kidney and the effect of several low-molecular weight proteins on that binding was determined. The Scatchard plot revealed a one-component binding type with a dissociation constant of 5.3 microM and 53.0 nmol/mg membrane protein for the number of binding sites. The binding of the cationic lysozyme was inhibited competitively by the addition of cationic cytochrome c to the incubation medium, while the neutral myoglobin had no effect. The anionic beta-lactoglobulin A inhibited the lysozyme binding in a noncompetitive manner. These data suggest that the binding takes place between positively charged groups of the protein molecule and negative sites on the brush-border membrane, and, the competition between the cationic cytochrome c and the cationic lysozyme for the binding sites may be responsible for the inhibitory effect of cytochrome c on renal lysozyme reabsorption. The binding step at the brush-border membrane appears to be cation-selective.
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PMID:Effect of low-molecular-weight proteins on protein (lysozyme) binding to isolated brush-border membranes of rat kidney. 632 Aug 87

Photobacterium leiognathi closely resembles Escherichia coli with respect to cell lysis by lysozyme, and the fractionation of outer and cytoplasmic membranes. The two organisms differ in their phospholipid contents and, more significantly, in outer membrane protein compositions.
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PMID:Comparative biochemistry of the cell envelopes of Photobacterium leiognathi and Escherichia coli. 635 61

The glucose phosphotransferase system (PTS) of Streptococcus mutans GS5 has been partially characterized, using fractions derived from cells treated with the muramidase mutanolysin. Membranes retained functional PTS enzymes for the phosphoenolpyruvate-dependent phosphorylation of glucose, fructose, and mannose. This was confirmed by assaying membranes directly for enzyme I (EI) and enzyme IIglc (EIIglc) by employing specific phosphoryl-exchange reactions for each factor. Membranes prepared from glucose PTS- mutants, however, were either deficient in glucose phosphorylation or reflected the "leakiness" displayed by whole cells. Mutant membranes were unable to catalyze the glucose:glucose 6-phosphate transphosphorylation reaction, indicating a defective EIIglc in these fractions. Although total cellular EI activities in the mutant clones were about the same as that measured for the wild-type strain by employing the pyruvate:phosphoenolpyruvate phosphoryl-exchange reaction, mutant membranes were found to possess less than 10% of the specific EI activity of wild-type membranes. The cytoplasmic fractions of mutants, however, displayed markedly increased specific activities for this enzyme when compared with wild-type extracts. These results strongly suggest a molecular association of EI with a normal membrane protein, perhaps EIIglc, that is absent in mutants. This would explain the absence of fructose PTS activity in glucose PTS- mutant membranes despite the fact that whole cells of these clones are normal for this transport function.
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PMID:Glucose phosphoenolpyruvate-dependent phosphotransferase system of Streptococcus mutans GS5 studied by using cell-free extracts. 671 47

1. The outer membrane of a phospholipase A-deficient mutant of Escherichia coli K12, isolated without the use of EDTA and lysozyme, showed the same freeze-fracture morphology as that seen in cells and remained stable for hours as observed by 31P-NMR. 2. 31P-NMR spectroscopy of the isolated outer membranes revealed that the lipopolysaccharide exists in the same physical state as in phospholipid-lipopolysaccharide liposomes and is most probably arranged in a bilayer at 37 degrees C. The outer membrane contains most or all of the phospholipids at 37 degrees C, and all the phospholipids at 20 degrees C, as a bilayer. 3. The 31P-NMR spectroscopy of the outer membranes from a mutant strain lacking the major outer membrane protein b, c and d (60% of the total outer membrane protein) yields virtually the same spectrum as the wild-type outer membranes, although most of the particles and pits which were observed in wild-type outer membranes in freeze-fracture electron microscopy were absent. 4. Whereas treatment of wild-type outer membranes with calcium ions has no effect on the 31P-NMR spectrum, treatment with EDTA results in more motion of the lipopolysaccharide.
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PMID:31P nuclear magnetic resonance and freeze-fracture electron microscopy studies on Escherichia coli. III. The outer membrane. 676 82

Induction of a major outer membrane protein, H1, in Pseudomonas aeruginosa resulted in decreased susceptibility to gentamicin and streptomycin. Mutants which overproduce protein H1 and cells in which H1 is induced in response to growth conditions had altered kinetics of uptake and killing. It was further demonstrated that gentamicin and streptomycin interact with the outer membrane to permeabilize it to lysozyme and to increase the permeation of a chromogenic beta-lactam, nitrocefin. Experiments with inhibitors of aminoglycoside uptake showed that uptake was not required to increase permeability. Mg2+ at 1 mM totally inhibited aminoglycoside-mediated outer membrane permeabilization. We propose that the uptake and killing by these aminoglycosides requires interaction with an Mg2+ binding site at the outer membrane, permitting aminoglycoside uptake into the periplasm.
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PMID:Involvement of the outer membrane in gentamicin and streptomycin uptake and killing in Pseudomonas aeruginosa. 679 44


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