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)

1. The mucopeptide component of wall preparations from Bacillus licheniformis was obtained in soluble form by treatment of the acid-insoluble residue of walls with lysozyme. 2. The soluble mucopeptide contains glutamic acid, diaminopimelic acid, alanine, N-acetylglucosamine and N-acetylmuramic acid in the molecular proportions 1.0:1.0:1.6:0.8:0.7. In addition approx. 1 mole of amide/mole of glutamic acid is present. Essentially all of the dry weight and nitrogen content of soluble mucopeptide is accounted for by these constituents. 3. The optical configurations of the amino acids were determined. Approx. 0.6 mole of d-alanine and 1.0 mole of l-alanine are present/mole of glutamic acid. 4. The structures of several small peptides derived from soluble mucopeptide after mild acid hydrolysis were established. 5. The structure of soluble mucopeptide from B. licheniformis is discussed on the basis of these results together with data on the number of free amino groups present in soluble mucopeptide.
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PMID:The cell wall of Bacillus licheniformis N.C.T.C. 6346. Composition of the mucopeptide component. 572 70

1. Soluble mucopeptide was prepared by lysozyme treatment of acid-extracted walls of Bacillus licheniformis N.C.T.C. 6346 and separated into fractions differing in molecular size by chromatography on Sephadex G-25 and G-50. 2. About 16% of the weight of soluble mucopeptide has a weight-average molecular weight in excess of 20000. About one half has a weight-average molecular weight of less than 2000 and the balance of soluble mucopeptide is of intermediate size. 3. In the mucopeptide fractions isolated from Sephadex there is a correlation between the weight-average molecular weight, the number of non-reducing muramic acid residues and the proportion of diaminopimelic acid residues recovered after treatment with 1-fluoro-2,4-dinitrobenzene. 4. The extent of cross-linking between peptide side chains is relatively low, even in mucopeptide material of the large molecular size. 5. The small amount of residual phosphorus present in preparations of B. licheniformis soluble mucopeptide remains associated mainly with mucopeptide material of large molecular size. 6. The mucopeptide components of lowest molecular weight are not produced as artifacts during the preparation of soluble mucopeptide, but are apparently incorporated in the insoluble mucopeptide present in walls of exponentially growing cells. 7. Soluble mucopeptide isolated in a complex with acidic polymers after lysozyme treatment of walls of B. licheniformis N.C.T.C. 6346 and Bacillus subtilis W23 retains a high molecular weight when the covalent bonds between mucopeptide and the acidic polymers are broken. 8. Pure fragments were isolated from B. licheniformis soluble mucopeptide. A major component, C1, of the material of smallest size is made up of one residue each of N-acetylglucosamine, N-acetylmuramic acid, l-alanine, glutamic acid and diaminopimelic acid. The N-acetylglucosamine is in beta-glycosidic linkage with a reducing N-acetylmuramic acid residue. The peptide unit is probably amidated. A quantitatively minor component, C2, has amino acid and amino sugar composition identical with that of component C1, but probably lacks an amide group. Another fragment, B1, is made up of two molecules of component C1 or C2 that are joined together through a molecule of d-alanine.
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PMID:The cell wall of Bacillus licheniformis N.C.T.C. 6346. Isolation of low-molecular-weight fragments from the soluble mucopeptide. 572 71

Extracts of Acanthamoeba castellanii (Neff) contain alpha- and beta-glucosidase, beta-galactosidase, beta-N-acetylglucosaminidase, amylase, and peptidase. All of these activities are optimal between pH 3 and 4. These extracts also were found to clarify suspensions of cell walls from nine different gram-positive bacteria, including Micrococcus lysodeikticus. The pH optimum for the lytic activity was between 3 and 4. The extent of lysis of the various cell walls did not correlate with the release of free amino groups and of free N-acetylated sugars from the walls during digestion with these extracts. Suspensions of cell walls of Escherichia coli (a gram-negative bacterium), Cordiceps militaris (a fungus), and Acanthamoeba cysts, as well as of colloidal chitin, were not clarified by incubation with these extracts, although reducing sugars were released from each of these materials. Exhaustive digestion of M. lysodeikticus walls by lysozyme released no free N-acetylglucosamine. The products of exhaustive digestion of this cell wall with Acanthamoeba extracts were free N-acetylglucosamine, free N-acetylmuramic acid, glycine, alanine, glutamic acid, lysine, and N-acetylmuramic acid peptide fragments. These results suggest that the amoeba extracts contain endo- and exo-hexosaminidases, in addition to beta-hexosaminidase and peptide hydrolases.
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PMID:Effect of lytic enzymes of Acanthamoeba castellanii on bacterial cell walls. 578 74

Bacillus subtilis 168 has been found to possess a high-affinity transport system for N-acetyl-D-glucosamine (GlcNAC). The Km for uptake was approximately 3.7 microM GlcNAc, regardless of the nutritional background of the cells. Apparent increases in Vmax were noted when the bacteria were grown in the presence of GlcNAc. The uptake of GlcNAc by B. subtilis was highly stereoselective; D-glucose, D-glucosamine, N-acetyl-D-galactosamine, D-galactose, D-mannose, and N-acetylmuramic acid did not inhibit GlcNAc uptake. In contrast, glycerol was an effective inhibitor of [3H]GlcNAc transport and incorporation. Partial inhibition of GlcNAc uptake was observed with azide, fluoride, and cyanide anions, carbonyl cyanide-m-chlorophenyl hydrazone, methyltriphenylphosphonium bromide, N,N'-dicyclohexylcarbodiimide, gramicidin, valinomycin, monensin, and nigericin. Two anions, arsenite and iodoacetate, were potent inhibitors of the uptake of GlcNAc in B. subtilis. Results from paper chromatography showed that there was no intracellular pool of free GlcNAc and that the acetylamino sugar was probably phosphorylated during transport. A modification of the Park-Hancock cell fractionation scheme indicated that cells grown on glycerol or D-glucose incorporated [3H]GlcNAc primarily into the cell wall fraction. When GlcNAc was used as the sole carbon source, label could be demonstrated in fractions susceptible to protease and nuclease, as well as lysozyme, showing that the N-acetylamino sugar was utilized in macromolecular synthesis and energy metabolism.
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PMID:Transport and incorporation of N-acetyl-D-glucosamine in Bacillus subtilis. 617 2

The mechanisms involved in the activation of autolytic enzymes in Staphylococcus aureus, by leukocyte extracts, cationic proteins, phospholipase A2, amines, and membrane-damaging agents was studied in a resting cell system as well as by growing staphylococci. The bacteria were labeled with [14C]N-acetylglucosamine and were subjected to a variety of agents either in 0.1 M acetate buffer, pH 5.0, or in phosphate buffer, pH 7.4. While intact log-phase cultures were found to undergo partial autolysis at pH 5.0 and almost complete lysis at pH 7.4, both heat-killed bacteria and bacterial cell walls were completely resistant to autolysis in buffers. Autolysis at pH 5.0 can be further activated by leukocyte extracts, nuclear histone, crystalline ribonuclease, egg-white and human lysozyme, phospholipase A2, as well as by spermine, spermidine, and polymyxins B and E. The addition of viable log-phase bacteria to radiolabeled heat-killed staphylococci or to radiolabeled cell walls which had been cleaned off autolytic enzymes resulted in degradation of the radiolabeled targets. The data suggest that the various inducers of autolysin activation caused leakage of autolytic enzymes from the intact bacteria which attacked the depolymerized the bacterial cell walls. Anionic polyelectrolytes like heparin, dextran sulfate, suramine, polyglutamic acid, and liquid (polyanethole sulfonic acid) markedly inhibited both spontaneous and induced lysis. Staphylococci which had grown in the presence of anionic polyelectrolytes became highly resistant to lysis triggered by any of the inducers of autolysis. Since inflammatory exudates are known to be rich in anionic polyelectrolytes, it is suggested that the prolonged survival of intact bacterial cells in such a milieu may be due to the inactivation of autolytic enzymes. It is also postulated that the degradation of certain bacterial species following phagocytosis or extracellular degradation may not be the result of the action of hydrolytic enzymes but rather the result of activation by leukocyte factors of autolytic enzymes which lead to bacteriolysis.
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PMID:Effect of leukocyte hydrolases on bacteria XVI. Activation by leukocyte factors and cationic substances of autolytic enzymes in Staphylococcus aureus: modulation by anionic polyelectrolytes in relation to survival of bacteria in inflammatory exudates. 618 97

A comparison was made between properties of a recently discovered Entamoeba histolytica lectin which has a carbohydrate specificity for N-acetylglucosamine oligosaccharides and the previously found toxin-like principle of the ameba. A separation between these two activities was achieved upon subcellular fractionation by high speed centrifugation of freeze-thawed disrupted E. histolytica trophozoites (strain HM-1). Practically all of this lectin activity, as determined by hemagglutination of glutaraldehyde-fixed human erythrocytes, was found associated with the sedimented membrane fraction. This fraction did not affect monolayers of tissue-cultured mammalian cells. On the other hand, the soluble supernatant solution caused extensive damage to the tissue-cultured cells (change in morphology and detachment of cells). Both the lectin and toxin activities were heat-labile and their activities were preserved by the presence of reducing agents and proteolytic enzyme inhibitors. In contrast to the toxin, the isolated lectin was inactive at pH 7.2 and active only at pH 5.7-6.0. Both the lectin and toxin were inhibited by a number of macromolecular compounds such as chitin, peptidoglycan, bovine serum and an IgA fraction isolated from human colostrum. Only the lectin activity, however, was inhibited by low molecular weight chitin oligosaccharides (GlcNAc)n=2-6 or by lysozyme-digested peptidoglycan subunits. Moreover, fetuin and a ganglioside mixture extracted from ox brain were found to inhibit only the toxin-like activity. The IgG fraction of sera from patients with invasive amebiasis neutralized both lectin and toxin-like activities, while IgG from normal sera failed to neutralize either activity. Although our results indicate that in E. histolytica, lectin and toxin are two separate activities, both of them share a considerable number of properties which does not exclude the possibility that they may be related.
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PMID:Lectin and toxin-like activities of Entamoeba histolytica: comparison of properties. 626 46

Bindings of calcium to lysozyme and its derivatives were studied by UV difference spectroscopy at various pH's. The binding constant was ca. 40 m-1 at around neutral pH. The binding caused proton release from lysozyme and did not inhibit the binding of tri-N-acetylglucosamine to lysozyme. In the presence of 0.2 M Ca2+, lysozyme showed 26% of the activity of the free enzyme toward hexa-N-acetylglucosamine but the cleavage pattern was similar to that of the free enzyme. Thus, calcium was predicted to bind near the catalytic carboxyls to cause inhibition of lysozyme activity. It was found from the results of protease digestion that calcium binding shifted the native-denatured transition in lysozyme toward the native state.
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PMID:Binding of calcium to lysozyme and its derivatives. 627 38

A highly specific aggregation factor for Streptococcus sanguis H1 (AFH1) was obtained by lysozyme treatment of Actinomyces viscosus T14V. At 1 micrograms/ml, AFH1 aggregated a suspension of S. sanguis H1, with which A. viscosus T14V coaggregates by a mechanism not inhibited by lactose: even at much higher levels AFH1 caused little or no aggregation of streptococci from other coaggregation groups (J. O. Cisar et al., Infect. Immun. 24:742-752, 1979). The most active fraction of AFH1 obtained by gel chromatography (near the void volume of Bio-Gel A1.5 m) reacted as a single antigen with anti-A. viscosus T14V serum and was unrelated to the fimbrial antigens of A. viscosus T14V. Smaller molecular fractions, at high levels, inhibited aggregation of S. sanguis H1 by high-molecular-weight AFH1 as well as coaggregation of S. sanguis H1 with A. viscosus T14V. The AFH1 fraction with high aggregating activity was composed of approximately 53% cell wall components (alanine, glutamine, lysine, N-acetylglucosamine, and N-acetylmuramic acid). 40% polysaccharide (N-acetylgalactosamine, rhamnose, and 6-deoxytalose), and 7% protein; teichoic acid was not detected. The fraction which inhibited aggregation and coaggregation contained much less of the cell wall constituents and more of the polysaccharide than the fraction with potent aggregating activity. Aggregation was completely prevented either by treating AFH1 with 0.01 M periodate at 25 degrees C for 4 h or by treating S. sanguis H1 with heat or pronase. A role for electrostatic forces in the aggregation was indicated by: (i) NaCl inhibition of aggregation, and (ii) a great decrease in aggregation potency as a result of chemical modification of either cationic or anionic groups of AFH1. On the other hand, NaCl reversed the aggregation only very weakly. The overall data suggest that a carbohydrate-protein interaction may be dominant in the aggregation of S. sanguis H1 by AFH1 and in the coaggregation of S. sanguis H1 with A. viscosus T14V.
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PMID:A factor from Actinomyces viscosus T14V that specifically aggregates Streptococcus sanguis H1. 630 57

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

Bacteriophage T4 particle-associated lysozyme, purified to electrophoretic homogeneity, was found to be a protein with a relative molecular mass of 15000. The lysozyme was purified from the particles of bacteriophage T4 e mutant and from the lysates of the 5tsl e T4 mutant, in which the enzyme is in soluble form. In the purification procedure advantage was taken of the affinity of the enzyme for GlcNAc-MurNac-LAla-DGlu-msA2pm-DAla (C6 muropeptide), one of the products of the digestion of Escherichia coli murein with lysozyme. The test for the quick estimation of bacteriolytic activity of the enzyme, using E. coli B freeze-dried cells, is described. The pH optimum of the particle-associated lysozyme was equal to about 6.0, ionic strength optimum to 0.05-0.1 M, and optimum Triton X-100 concentration to 1%, when this substrate was used. Some of the aspects of the possible biological significance of the particle-associated lysozyme in bacteriophage T4 infection are discussed.
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PMID:Purification and some properties of bacteriophage T4 particle-associated lysozyme. 634 57


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