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)

The peptidoglycans from several Gram-negative and Gram-positive periodontal pathogens were isolated, purified, and characterized both morphologically and chemically. In addition, the effects of the mureolytic enzymes, lysozyme, M-1 N-acetyl-muramidase, and the AM-3 endopeptidase, on the peptidoglycans were examined. These enzymes were found to be highly effective in the degradation of the purified peptidoglycans; however, a Bacteroides capillus peptidoglycan-protein complex exhibited a greater resistance to these enzymes. Morphologically, the peptidoglycans consisted of large saccular sheets which, when viewed by scanning electron microscopy, contained numerous holes and tears. Chemically, the peptidoglycans consisted of muramic acid, glucosamine, alanine, glutamic acid, and meso-diaminopimelic acid (DAP). One Bacteroides species, Bacteroides gingivalis strain W, contained glycine and LL-DAP, suggestive of an indirectly cross-linked A3 gamma peptidoglycan.
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PMID:Isolation and characterization of the peptidoglycans from selected gram-positive and gram-negative periodontal pathogens. 398 14

Autolysin-defective pneumococci continue to synthesize both peptidoglycan and teichoic acid polymers (Fischer and Tomasz, J. Bacteriol. 157:507-513, 1984). Most of these peptidoglycan polymers are released into the surrounding medium, and a smaller portion becomes attached to the preexisting cell wall. We report here studies on the degree of cross-linking, teichoic acid substitution, and chemical composition of these peptidoglycan polymers and compare them with normal cell walls. peptidoglycan chains released from the penicillin-treated pneumococci contained no attached teichoic acids. The released peptidoglycan was hydrolyzed by M1 muramidase; over 90% of this material adsorbed to vancomycin-Sepharose and behaved like disaccharide-peptide monomers during chromatography, indicating that the released peptidoglycan contained un-cross-linked stem peptides, most of which carried the carboxy-terminal D-alanyl-D-alanine. The N-terminal residue of the released peptidoglycan was alanine, with only a minor contribution from lysine. In addition to the usual stem peptide components of pneumococcal cell walls (alanine, lysine, and glutamic acid), chemical analysis revealed the presence of significant amounts of serine, aspartate, and glycine and a high amount of alanine and glutamate as well. We suggest that these latter amino acids and the excess alanine and glutamate are present as interpeptide bridges. Heterogeneity of these was suggested by the observation that digestion of the released peptidoglycan with the pneumococcal murein hydrolase (amidase) produced peptides that were resolved by ion-exchange chromatography into two distinct peaks; the more highly mobile of these was enriched with glycine and aspartate. The peptidoglycan chains that became attached to the preexisting cell wall in the presence of penicillin contained fewer peptide cross-links and proportionally fewer attached teichoic acids than did their normal counterparts. The normal cell wall was heavily cross-linked, and the cross-linked peptides were distributed equally between the teichoic acid-linked and teichoic acid-free fragments.
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PMID:Peptidoglycan cross-linking and teichoic acid attachment in Streptococcus pneumoniae. 400 47

Electron microscope examination of negatively stained or thin-sectioned cells of Spirochaeta stenostrepta treated with penicillin or lysozyme showed that the peptidoglycan was present as a thin, electron-dense layer adjacent and external to the cytoplasmic membrane. The peptidoglycan was isolated from cells of S. stenostrepta and Spirochaeta litoralis by a procedure including treatments with sodium lauryl sulfate and Pronase. Hydrolysates of the isolated S. stenostrepta and S. litoralis peptidoglycans contained glucosamine, muramic acid, glutamic acid, l-ornithine, and alanine in molar ratios of 0.90:0.85:1.00:1.00:1.40 and of 0.63:0.63:0.99:1.00:1.41, respectively. Determination of N-terminal residues suggested that nearly 50% of the ornithine in S. stenostrepta and S. litoralis peptidoglycans was involved in peptide cross-linkage. The peptidoglycan layer of S. stenostrepta was sensitive to lysozyme and myxobacter AL-1 protease.
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PMID:Peptidoglycan of free-living anaerobic spirochetes. 412 18

The genetic control of the immune response may be either specific for antigenic carrier or for determinant. We describe here results which show that a carrier-dependent strain defect in immune response is reflected in thymocytes. These results are in agreement with our hypothesis that the genetic defect in the immune response is reflected in thymocytes when the poor response is at the carrier level, whereas it is expressed in the bone marrow population when the low responsiveness is strictly at the determinant level. SWR mice are low responders to multichain polyproline. Furthermore, this mouse strain does not produce antibodies to determinants such as peptides of phenylalanine and glutamic acid (Phe,Glu) or to the loop peptide of lysozyme when attached to polyproline, although they respond well to the same antigenic determinants when conjugated to multichain poly(DL-alanine). Transfer experiments in which irradiated SWR recipients were injected with excess of DBA/1 thymocytes (which do not exhibit a defect in response to polyproline) mixed with graded numbers of SWR marrow cells, prior to immunization with poly(Tyr,Glu)-poly(Pro)--poly(Lys), have indicated that the poor response potential of SWR mice to polyproline is not reflected in their bone marrow cells. Allogeneic transfers in which mixtures of thymocytes and marrow cells from high and low responders were injected into irradiated mice, followed by immunization with poly(Tyr,Glu)-poly(Pro)--poly(Lys) or poly(Phe,Glu)-poly(Pro)--poly(Lys) have demonstrated a clear defect in the thymus derived population of SWR mice when the response potential to polyproline and to determinants attached to it was tested.
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PMID:The role of the thymus in a genetically controlled defect of the immune response at the carrier level. 413 52

The pinocytosis-inducing effect of a number of molecular species was studied in cultures of mouse macrophages. Agents were added to a basal medium containing 1% NBCS-No. 199 and allowed to interact with cells for 150 min. Vesicle counts were then performed and compared to control cells in the basal medium. Certain proteins, i.e. albumin and fetuin, with isoelectric points of five and below were found to be potent stimulators of vesicle formation. Basic proteins including lysozyme, histone, and protamine had little influence at sublethal concentrations. The pinocytosis-stimulating activity of bovine plasma albumin could be markedly depressed by removal of bound fatty acids. The addition of either oleic or linoleic acid to de-fatted albumin restored its inducing properties to initial levels. The activity of fetuin could be abolished by either mild acid hydrolysis or neuraminidase digestion. Both procedures removed the majority of the sialic acid content of fetuin. The D and L isomers of polyglutamic acid were found to produce a marked increase in pinosome production. In contrast, poly-DL-lysine was not effective. Neutral and basic amino acids were without significant effect on pinocytosis, whereas aspartic and glutamic acids were stimulatory. The amides of glutamic and aspartic acid did not induce pinocytosis. The unnatural D isomers of glutamic, aspartic, leucine, and phenylalanine inhibited pinocytosis. The inhibition by D-glutamic acid could be reversed with the L isomer. A number of acid mucopolysaccharides, including heparin, hyaluronic acid, and chondroitin sulfate, were excellent inducers. High molecular weight dextran was without significant stimulatory effect whereas dextran sulfate was very active. Both desoxyribonucleic acid and ribonucleic acid enhanced pinosome formation. A number of low molecular weight anions including N-acetylneuraminic acid were found to enhance vesicle formation. In general, anionic molecules were better inducers than either neutral or cationic species. The minimum effective dose of macroanions was a function of molecular weight and their activity appeared unrelated to specific chemical groupings.
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PMID:The regulation of pinocytosis in mouse macrophages. II. Factors inducing vesicle formation. 422 63

Some properties of a d-glutamic acid auxotroph of Escherichia coli B were studied. The mutant cells lysed in the absence of d-glutamic acid. Murein synthesis was impaired, accompanied by accumulation of uridine-5'-diphosphate-N-acetyl-muramyl-l-alanine (UDP-MurNac-l-Ala), as was shown by incubation of the mutant cells in a cell wall medium containing l-[(14)C]alanine. After incubation of the parental strain in a cell wall medium containing l-[(14)C]glutamic acid, the acid-precipitable radioactivity was lysozyme degradable to a large extent. Radioactive UDP-MurNac-pentapeptide was isolated from the l-[(14)C]glutamic acid-labeled parental cells. After hydrolysis, the label was exclusively present in glutamic acid, the majority of which had the stereo-isomeric d-configuration. Compared to the parent the mutant incorporated less l-[(14)C]glutamic acid from the wall medium into acid-precipitable material. Lysozyme degraded a smaller percentage of the acid-precipitable material of the mutant than of that of the parent. No radioactive uridine nucleotide precursors could be isolated from the mutant under these conditions. Attempts to identify the enzymatic defect in this mutant were not successful. The activity of UDP-MurNac-l-Ala:d-glutamic acid ligase (ADP; EC 6.3.2.9) (d-glutamic acid adding enzyme) is not affected by the mutation. Possible pathways for d-glutamic acid biosynthesis in E. coli B are discussed.
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PMID:Properties of a D-glutamic acid-requiring mutant of Escherichia coli. 457 91

Differences between the transfer ribonucleic acid (tRNA) of spores and exponentially growing cells of Bacillus subtilis 168 were compared by co-chromatography on reversed-phase column RPC-5. This system gave excellent resolution of isoaccepting species in 1 to 2 hr using a 200-ml gradient. Two methods were used to extract spore tRNAs, a procedure using a Braun homogenizer and a pretreatment with dithiothreitol followed by lysis with lysozyme. Where changes were observed, column elution profiles of spore tRNAs were independent of the extraction method used. Three kinds of changes between the profiles of vegetative cell tRNA and spore tRNA were observed: (i) no change; phe-, val-, ala-, asp-, ileu-, pro-, met-, fmet-, and his-tRNAs, (ii) a change in the ratio of existing peaks; gly-, tyr-, leu-, ser-, thr-, aspn-, and arg-tRNAs, and (iii) the appearance or disappearance of unique peaks; lys-, glu-, and trp-tRNAs.
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PMID:Analysis of isoaccepting transfer ribonucleic acid species of Bacillus subtilis: chromatographic differences between transfer ribonucleic acids from spores and cells in exponential growth. 463 22

Four proteins, which have been designated A, B, C and D, have been purified from human parotid saliva. These proteins are the major constituents of parotid saliva which migrate rapidly to the anode in polyacrylamide electrophoresis at pH9.5. Gel filtration and polyacrylamide electrophoresis were employed in the purification procedures. After purification all four preparations were tested for homogeneity by electrophoresis at pH2.8 and 9.5, by isoelectric focusing in the pH range 3-10, by immunodiffusion, and by sedimentation in the analytical ultracentrifuge. None of the proteins showed significant activity in assays for amylase, acid and alkaline phosphatase, protease, lysozyme, ribonuclease, peroxidase, beta-glucuronidase, beta-galactosidase, iron-binding activity and esterase. No cross-reactions were detected with antisera specific for lactoferrin and 15 serum proteins. All four proteins were rich in glutamic acid, proline and glycine and were lacking completely the sulphur-containing amino acids. Proteins A and C contained no threonine or tyrosine. Carbohydrate could be demonstrated only in protein A at a concentration of 4% of the total protein.
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PMID:Purification and partial characterization of four proteins from human parotid saliva. 500 93

Cell walls from Lactobacillus fermenti were prepared by differential centrifugation of disrupted cells, with and without trypsin treatment. Approximately 16% of the dry weight of walls was found in a crude trichloroacetic acid extract of the walls; half of this amount remained upon further purification. The purufied extract lacked alanine, but contained substantial amounts of glucosamine. The walls constituted 23 to 33% of the dry weight of the cell. The chemical composition of the various types of wall preparations and of the peptidoglycan from them was studied. The peptidoglycan contained equimolar proportions of glucosamine, muramic acid, l-alanine, d-glutamic acid, and lysine, with somewhat lower proportions of d-aspartic acid and d-alanine. The chemical composition of the peptidoglycan is similar to that reported for three other lactobacilli. In addition to the major constituents of walls and peptidoglycan, there were several minor amino acids. The protein and the amounts of the minor amino acids decreased, and among these threonine and arginine were completely absent from preparations obtained with trypsin. Such preparations contained higher proportions of the d-isomers of alanine, glutamic acid, and aspartic acid as compared to walls and peptidoglycan prepared without trypsin. In addition, walls isolated with the use of trypsin were susceptible to lysozyme, whereas those prepared without trypsin were not. However, the trypsin treatment did not result in any change of the ultrastructure as revealed by electron microscope studies.
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PMID:CELL WALL AND PEPTIDOGLYCAN FROM Lactobacillus fermenti. 554 95

Walls of the pigmented strain of Micrococcus radiodurans showed several layers in the electron microscope. These layers include an outermost network structure removed by trypsin, a fragile soft layer containing hexagonally packed subunits, and a rigid layer penetrated by numerous holes. The two inner layers were separated by a process of autolysis, trypsin treatment, and gradient centrifugation. The hexagonally packed layer was less dense, pink in color, and it contained carotenoids, lipid, protein, and polysaccharide. The lipid consisted of odd-numbered as well as even-numbered fatty acids, and the polysaccharide contained rhamnose and mannose, but it did not contain heptose. The "holey" layer was white and was composed of a mucopeptide containing glucosamine, muramic acid, and four main amino acids (glutamic acid, alanine, glycine, and l-ornithine, in the ratios of 1:1.7:1.8:1.2, respectively). This layer also contained phosphorus, glucose, and a trace of meso- and ll-diaminopimelic acid. A white mutant, W(1), of M. radiodurans had no pigment or lipid in its walls, but it contained small amounts of the "hexagonal" layer. The holey layer, constituting the bulk of the wall, was similar in morphology and composition to that layer in the pigmented strain. Lysozyme did not remove the lipoprotein-polysaccharide component from the walls of the pigmented strains, and the hexagonally packed structure was not visibly affected, except for change in a minor structure. Most of the mucopeptide layer was solubilized by lysozyme, but a structureless bag-shaped residue was left. This residue contained phosphorus, carbohydrate, and limited amino acids, but it did not contain muramic acid, glucosamine, or ornithine. Aqueous phenol removed a lipoprotein component from strain R(1), which contained limited fatty acids. It also removed meso- and ll-diaminopimelic acid.
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PMID:Morphology and chemistry of cell walls of Micrococcus radiodurans. 564 Mar 86


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