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 Mycobacterium smegmatis arabinogalactan polysaccharide has been isolated from the cell wall by saponification and extraction to remove lipids and subsequent solubilization by treatment with lysozyme. Analysis for neutral sugars demonstrated the presence of D-arabinose and D-galactose in a ratio of 3:1, respectively. Reductive cleavage of the fully methylated polysaccharide in the presence of triethylsilane and trimethylsilyl trifluoromethanesulfonate and subsequent acetylation in situ gave six partially methylated 1,4-anhydroalditol acetates as the major products and three partially methylated 1,5-anhydroalditol acetates as minor products. Partially methylated 1,5-anhydroalditol acetates were not formed when reductive cleavage was accomplished with triethylsilane and a mixture of trimethylsilyl methanesulfonate and boron trifluoride etherate as the catalyst, demonstrating that the polysaccharide is exclusively comprised of furanosyl residues. The partially methylated anhydroalditols so produced were identified by comparison to authentic standards. Their identifies are consistent with the presence in the M. smegmatis arabinogalactan of an octasaccharide repeating unit comprised of a nonreducing terminal D-arabinofuranosyl group, a 2-O-linked D-arabinofuranosyl residue, three 5-O-linked D-arabinofuranosyl residues, a 3,5-di-O-linked D-arabinofuranosyl residue, a 5-O-linked D-galactofuranosyl residue, and a 6-O-linked D-galactofuranosyl residue.
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PMID:Isolation and analysis by the reductive-cleavage method of linkage positions and ring forms in the Mycobacterium smegmatis cell-wall arabinogalactan. 222 5

1. Tests for glycosidases were performed in homogenates of Brachionus plicatilis. 2. Hydrolytic activity was detected with the following substrates: (a) with synthetic substrates (NP = 4-nitrophenyl): NP-alpha- and NP-beta-D-glucopyranoside, NP-alpha- and NP-beta-D-galactopyranoside, NP-N-acetyl-beta-D-glucosaminide, NP-N-acetyl-beta-D-galactosaminide, NP-alpha- and NP-beta-D-mannopyranoside and NP-alpha-L-fucopyranoside; (b) with disaccharides: sucrose, maltose, trehalose, isomaltose, cellobiose, gentiobiose and lactose; (c) with polysaccharides: laminarine, carboxymethyl-cellulose, avicel, Micrococcus luteus (for lysozyme) and 4-nitrophenyl-alpha-D-maltoheptaoside (for amylase). 3. The pH dependence of the glycosidase activities was determined. 4. The distribution of enzyme activities within fractions from the homogenate was studied in order to localize them within the cell. 5. Proteins from Brachionus homogenate were separated by SDS-gel electrophoresis and the positions of the following glycosidase activities were detected by assays performed on the gels (estimated molecular weights in parentheses): alpha-glucosidase (250,000); beta-glucosidase (200,000); beta-galactosidase (70,000); N-acetyl-beta-glucosaminidase (60,000).
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PMID:Glycosidases in Brachionus plicatilis (Rotifera). 232 73

The pathogenic Staphylococcus epidermidis strain RP62A (ATCC 35984) adheres to smooth surfaces by forming a tenacious bacterial film known as slime. The mechanism of slime production is not known; however, workers in the laboratory of G. Pier (Harvard Medical School, Boston, Mass.) have isolated from RP62A a galactose-rich capsular polysaccharide adhesin (CPA) which mediates the attachment of the organism to smooth surfaces. We have obtained two daughter strains from RP62A that no longer produce slime. One daughter strain, H4A, was obtained by selection for a spontaneous variant; the other strain, HAM892, was obtained by treating growing cultures of RP62A with acriflavin. Using an antiserum generated against whole cells of RP62A, we have examined lysozyme-lysostaphin digests of RP62A, H4A, and HAM892 by double immunodiffusion. The two strains that no longer produced slime no longer produced a particular antigen, which we refer to as the slime-associated antigen (SAA). SAA was also produced by unrelated strains of slime-producing S. epidermidis. SAA was heat and protease stable, had a molecular weight of greater than 50,000, and could be partially purified by chromatographing trypsin-digested material over a Sephadex G-200 column. Chemical analysis of partially purified SAA by gas-liquid chromatography found SAA to be glucose rich (59%) and galactose poor (1.4%). This analysis chemically distinguished SAA from CPA. When tested together by double immunodiffusion with anti-RP62A and anti-CPA antisera, partially purified SAA did not cross-react with CPA. Kinetic studies suggested that SAA is a marker for surface accumulation whereas CPA mediates initial adherence.
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PMID:Identification of an antigenic marker of slime production for Staphylococcus epidermidis. 238 26

Shaken cultures of Streptomyces venezuelae ISP5230 in minimal medium with galactose and ammonium sulphate as carbon and nitrogen sources, respectively, showed extensive sporulation after 72 h incubation at 37 degrees C. The spores formed in these cultures resembled aerial spores in their characteristics. The ability of the spores to withstand lysozyme treatment was used to monitor the progress of sporulation in cultures and to determine the physiological requirements for sporulation. In media containing ammonium sulphate as the nitrogen source, galactose was the best of six carbon sources tested. With galactose S. venezuelae ISP5230 sporulated when supplied with any of several nitrogen sources; however, an excess of nitrogen source was inhibitory. In cultures containing galactose and ammonium sulphate, sporulation was suppressed by a peptone supplement. The onset of sporulation was accompanied by a drop in intracellular GTP content. When decoyinine, an inhibitor of GMP synthase, was added to a medium containing starch and ammonium sulphate, a slight increase in sporulation was seen after 2 d. The suppression of sporulation by peptone in liquid or agar cultures was not reversed by addition of decoyinine. A hypersporulating mutant of S. venezuelae ISP5230 was altered in its ability to assimilate sugars. In cultures containing glucose the mutant sporulated more profusely than did the wild-type and did not acidify the medium to the same extent. However, the suppressive effect of glucose on sporulation was not merely a secondary result of acid accumulation.
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PMID:Sporulation of Streptomyces venezuelae in submerged cultures. 239 93

Fusobacterium nucleatum expresses lectinlike adherence factors which mediate binding to a variety of human tissue cells. Adherence is selectively inhibited by galactose, lactose, and N-acetyl-D-galactosamine. In this study, adherence of F. nucleatum to human peripheral blood polymorphonuclear neutrophils (PMNs) was investigated. The results indicated that the fusobacteria adhered to live and metabolically inactivated or fixed PMNs. Adherence of F. nucleatum resulted in activation of PMNs as determined by PMN aggregation, membrane depolarization, increased intracellular free Ca2+, superoxide anion production, and lysozyme release. Transmission electron micrographs showed that F. nucleatum was phagocytized by the PMNs. Microbicidal assays indicated that greater than 98% of F. nucleatum organisms were killed by PMNs within 60 min. Adherence to and activation of PMNs by F. nucleatum were inhibited by N-acetyl-D-galactosamine or lactose greater than galactose, whereas equal concentrations of glucose, N-acetyl-D-glucosamine, mannose, and fucose had little or no effect on F. nucleatum-PMN interactions. Pretreatment of the fusobacteria with heat (80 degrees C, 20 min) or proteases inhibited adherence to and activation of PMNs, but superoxide production was also stimulated by heated bacteria. The results indicate that interaction of F. nucleatum with PMNs is lectinlike and is probably mediated by fusobacterial proteins which bind to other human tissue cells. Adherence of F. nucleatum to PMNs in the absence of serum opsonins, such as antibodies and complement, may play an important role in PMN recognition and killing of F. nucleatum in the gingival sulcus and in the subsequent release of PMN factors associated with tissue destruction.
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PMID:Lectinlike interactions of Fusobacterium nucleatum with human neutrophils. 255 9

Membranes were isolated by French pressure cell extrusion of lysozyme-preincubated cells of the cyanobacterium Synechocystis 6714 after growth in the presence of 0.4 M NaCl for 4 days. These cells showed up to 6-fold respiratory activity (oxygen uptake) when compared to control cells. Separation of plasma and thylakoid membranes revealed that the major part of cytochrome c oxidase was associated with the latter. Immunoblotting of sodium dodecylsulfate polyacrylamide gel electrophorized membranes with antisera raised against subunit I, subunit II, and the holoenzyme of the aa3-type cytochrome oxidase from Paracoccus denitrificans gave specific and complementary cross-reactions at apparent molecular weights of about 25 and 17-18 kDa, respectively. Crude membranes were solubilized also with n-octyl glucoside, and the cytochrome oxidase was separated from the extract by affinity chromatography using immobilized cytochrome c from Saccharomyces cerevisiae. The enzyme was eluted with KCl/octyl glucoside. Dialysed and concentrated enzyme solution, which was free of b- and c-type cytochromes, gave reduced alpha- and gamma-peaks around 603 and 443 nm, respectively. Upon treatment of the sample with carbon monoxide the peaks were found at 593 and 433 nm, respectively. Photodissociation spectra of the CO-complexed enzyme were in full agreement with cytochrome aa3 being a functional cytochrome oxidase in Synechocystis 6714.
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PMID:Immunological and spectral characterization of partly purified cytochrome oxidase from the cyanobacterium Synechocystis 6714. 282 95

Addition of thiourea (TU) or dimethylthiourea (DMTU) decreased killing of Staphylococcus aureus, 502A, and decreased concentrations of hydrogen peroxide (H2O2), and hydroxyl radical (.OH), but not superoxide anion (O2-.) or lysozyme concentrations, in mixtures containing human neutrophils in vitro. Addition of TU or DMTU also decreased concentrations of H2O2, .OH, or hypochlorous acid (HOCl) in neutrophil-free mixtures exposed to beta-D-glucose and glucose oxidase, gamma irradiation, or HOCl, respectively. Our results suggest that TU or DMTU can decrease neutrophil-mediated killing of bacteria by inhibiting O2 metabolite-dependent bactericidal mechanisms.
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PMID:Thiourea and dimethylthiourea decrease human neutrophil bactericidal function in vitro. 284 72

Binding of human lactoferrin (hLf) by purified rat liver plasma membranes was studied to clarify whether the liver possesses specific hLf receptors. The binding was rapid between 4 degrees and 37 degrees C, with a pH optimum close to 5.0. At 22 degrees C and in glycine-NaOH (5 mM, pH 7.4) containing 150 mM NaCl and 0.5% albumin, 1 microgram of membrane bound a maximum of 11.8 ng hLf. The dissociation constant of the interaction was 1.6 X 10(-7) M. Other proteins of high isoelectric points (lactoperoxidase, lysozyme, and particularly salmine sulfate) and a piperazine derivative inhibited hLf binding in a concentration-dependent manner. In contrast, monosaccharides (galactose, N-acetylgalactosamine, mannose, and fucose) were ineffective. By omitting NaCl from the incubation buffer, binding was increased 3.6-fold. Erythrocyte ghosts bound hLf less firmly and alveolar macrophages more firmly than hepatic plasma membranes. Liver cell fractionations performed after the intravenous injection of labeled hLf showed that approximately 88% of the hepatic radioligand was associated with parenchymal cells. When binding was expressed per unit of cell volume, however, more hLf was present in nonparenchymal than in parenchymal cells, implying that the above value was determined by the relative cell masses rather than affinities alone. It is concluded that the binding of hLf by hepatic plasma membranes is electrostatic, i.e., is mediated by the cationic nature of the ligand, and that it is explicable in terms of a "specific nonreceptor interaction" of the generalized type proposed by Cuatrecasas and Hollenberg (Adv. Protein Chem. 30: 251-451, 1976).
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PMID:Interaction of human lactoferrin with the rat liver. 298 44

Structural studies were carried out on the acidic polymer fraction isolated from lysozyme digests of the N-acetylated cell walls of Bacillus cereus AHU 1356. The acidic polymer fraction contained glucosamine, galactose, rhamnose, glycerol and phosphorus in a molar ratio of 1:1:2:1:1, together with small amounts of glycopeptide components and muramic acid 6-phosphate. The hydrogen fluoride treatment led to removal of glycerol and phosphorus from the polymer without loss of other components. Results of the NaIO4 oxidation, methylation and proton magnetic resonance spectroscopy of the native and dephosphorylated preparations, in combination with data of the analysis of oligosaccharides obtained from partial hydrolysis of polysaccharide, led to the most likely structure of the repeating units of the acidic polysaccharide chain, ----4)N-acetylglucosaminyl-(alpha 1----3)rhamnosyl(alpha 1----3)galactosyl(alpha 1----4)[sn-glycerol 1-phospho-2]rhamnosyl(alpha 1----.
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PMID:Structural studies on the acidic polysaccharide of Bacillus cereus AHU 1356 cell walls. 298 63

Pathogenic mechanisms in infectious diseases often involve specific receptor-ligand interactions of cells and soluble molecules. To further elucidate structure-function relations for shigella toxin receptors, we studied binding of purified 125I-labeled toxin and biologic response under various conditions in an experimental model using HeLa cells. Response to toxin was reversibly inhibited by treatment of cells with trypsin or tunicamycin, an inhibitor of glycoprotein synthesis that also significantly inhibited toxin binding, a result indicating that the receptor is an N-linked glycoprotein. Removal of terminal beta-linked galactose from the HeLa cell surface with beta-galactosidase increased toxin binding and activity, and it also potentiated the effects of lysozyme and wheat-germ agglutinin, which recognize oligomeric beta 1----4-linked N-acetyl-D-glucosamine and inhibit toxin activity as well. Incubation of cells with beta-N-acetylglucosaminidase, which cleaves terminal beta-linked N-acetyl-D-glucosamine, inhibited toxin activity. Effects of beta-galactosidase were reversed by readdition of galactose to cell-surface oligosaccharide acceptors. The data demonstrate that alterations of a single sugar on cell-surface glycoproteins may have a dramatic effect on receptor activity and indicate that shigella toxin is a sugar-binding protein with specificity for beta 1----4-linked N-acetyl-D-glucosamine.
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PMID:Pathogenesis of shigella diarrhea: evidence for an N-linked glycoprotein shigella toxin receptor and receptor modulation by beta-galactosidase. 300 5


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