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 molecular characteristics of the dominant anion-exchange binding site of hen egg white lysozyme (HEWL) has been investigated using a combination of high-performance liquid chromatographic techniques and computer graphic analysis of the X-ray crystallographic structure. These studies have indicated that the site of highest electrostatic potential, in terms of the density of negatively charged amino acid side chains, is located around the catalytic cleft area. The four residues tentatively identified to be involved in the electrostatic binding domain were aspartic acid 48, 52, 101 and glutamic acid 35. The number of these charged groups correlated with the maximum value of the chromatographically determined retention parameter (Zc value). Variations in the range of experimental Zc values obtained under different elution conditions have been interpreted in terms of conformational flexibility of the structural domains of HEWL which result in the opening or closure of the catalytic cleft during the retention process.
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PMID:High-performance liquid chromatography of amino acids, peptides and proteins. C. Characterisation of coulombic interactive regions on hen lysozyme by high-performance liquid anion-exchange chromatography and computer graphic analysis. 225 50

Seven cationic substances--human and egg-white lysozyme, RNase, protamine, histone, poly-L-lysine and poly-L-arginine; five cationic lysosomal fractions from human polymorphonuclears (PMNs); RNA; poly-L-glutamic acid; DNA; heparin; endotoxin; mastocytotropic agent compound 48/80; and cytochalasin B were tested for the influence on chemotaxis and random migration of human PMNs using under-agarose migration and Boyden chambers with two filters and [51Cr]PMNs. The above substances were either preincubated with PMNs, added to chemoattractants, or used instead of chemoattractants. In under-agarose migration method chemotaxis was inhibited by 11-35% when egg-white lysozyme, protamine, heparin, endotoxin, or compound 48/80 was added to the cells. High concentration of cytochalasin B inhibited chemotaxis by 73%. Cationic fractions I and V and low concentration of cytochalasin B enhanced chemotaxis by 11%, 41%, and 30%, respectively. When human and egg-white lysozyme, DNA, or cytochalasin B was added to the chemoattractants, motility of PMNs was inhibited. Cationic fractions II and V from human PMNs, when used as chemoattractants, enhanced cellular motility by 143-167%. Random migration was enhanced by heparin and inhibited by cytochalasin B and by cationic fractions from human PMNs. These findings suggest that various cationic and anionic substances and cationic fractions from human PMNs have heterogeneous influence on random migration and chemotactic activity of human PMN. Analysis relating chemotaxis to phagocytosis and to intracellular bactericidal activity (ICBA) has shown several patterns. Protamine, poly-L-lysine, poly-L-arginine, and agent compound 40/80 all inhibit chemotaxis and enhance phagocytosis and ICBA; cationic fractions II and V enhanced all three functions, whereas cytochalasin B suppressed phagocytosis and ICBA and had concentration-dependent modulatory influence on chemotaxis. It implies diverse mechanisms of action and possible impact on inflammatory reactions.
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PMID:Modulation of locomotor activity of polymorphonuclear cells by cationic substances and cationic lysosomal fractions from human neutrophils. 241 86

The adherence of [3H]thymidine-labeled Streptococcus sanguis strains to bare hydroxyapatite and to hydroxyapatite coated with a range of concentrations of lysozyme, poly-L-lysine, poly-L-glutamic acid, whole saliva supernatant, and combinations of some of the above was studied. Adherence of several strains of S. sanguis to bare hydroxyapatite and saliva-coated hydroxyapatite was compared. Saliva present as a pellicle on the hydroxyapatite inhibited adherence of some strains (903, M-5, 73X11) and stimulated that of others (S35, B-4, 66X49). Strains 903 and S35 were chosen for further study. Adherence of both strains was stimulated up to fivefold by the presence of adsorbed lysozyme or poly-L-lysine on the hydroxyapatite, whereas poly-L-glutamic acid inhibited adherence (80 to 95%). Adherence of strain S35 to hydroxyapatite coated with combinations of saliva and (i) lysozyme, (ii) poly-L-lysine, or (iii) poly-L-glutamic acid was unaffected compared with adherence to hydroxyapatite coated with saliva alone. In contrast, adherence of strain 903 to hydroxyapatite coated with combinations of saliva and either lysozyme or poly-L-lysine was inhibited up to ca. 90% compared with hydroxyapatite coated with saliva alone. Strain 903 was also unaffected by combinations of poly-L-glutamic acid and saliva on the hydroxyapatite. Adherent cells of both strains were completely (greater than 90%) eluted with high-ionic-strength buffer from either bare hydroxyapatite or hydroxyapatite coated with lysozyme alone. Adherent cells of strain S35 were only poorly eluted (25%) from hydroxyapatite coated with either saliva alone or saliva and lysozyme. Strain 903 elution from hydroxyapatite coated with either saliva alone or saliva and lysozyme was essentially complete. These observations were taken to indicate that the two test strains adhered to saliva-coated hydroxyapatite by different mechanisms. Protein-coated hydroxyapatite was shown not to be saturated under the conditions described here. Examination by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the variously supplemented salivary pellicles formed on the hydroxyapatite demonstrated that major changes in salivary protein composition did not occur when lysozyme, poly-L-lysine, or poly-L-glutamic acid was used to supplement saliva. Lysozyme-dependent aggregation of strain 903 was shown not to occur under the conditions of our experiments. We suggest that the basis for stimulation of adherence to hydroxyapatite coated only with lysozyme is an increase in the cationic surface area available for electrostatic adherence of the microorganisms.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Adherence of Streptococcus sanguis to hydroxyapatite coated with lysozyme and lysozyme-supplemented saliva. 241 51

Chrysotile asbestos permeabilizes the plasma membrane of rabbit polymorphonuclear leukocytes (PMNs) which is evident from the release of the cytoplasmic enzyme lactate dehydrogenase (LDH) from the cell. When Ca2+ is present in the medium exocytosis is observed, evident from the release of the granule associated enzyme lysozyme which is not liberated in the absence of Ca2+. Asbestos-induced enzyme release is inhibited by polyanions or by removal of positive charges on asbestos, and resembles enzyme release induced by synthetic polycations. Pretreatment of PMNs with neuraminidase does not affect the ability of asbestos to induce enzyme release from these cells. Asbestos induces release of glucose from glucose-loaded liposomes, and this effect can be inhibited by the polyanion poly-D-glutamic acid. The results are compatible with the view that positive charges play a decisive role in the interaction between PMNs and asbestos, and that the primary target of asbestos could be the lipid bilayer of the membrane. The interaction results in a permeabilized plasma membrane. When Ca2+ is present in the medium it moves into the cell and causes exocytosis of the granule enzyme lysozyme. Inhibition of cytotoxicity by polyanion may cause a diminished Ca2+-influx and hence inhibition of lysozyme release.
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PMID:The involvement of ionic interactions during asbestos-induced enzyme release from polymorphonuclear leukocytes. 247 90

The roles of the catalytic active-site residues aspartic acid-52 and glutamic acid-35 of chicken lysozyme (EC 3.2.1.17) have been investigated by separate in vitro mutagenesis of each residue to its corresponding amide (denoted as D52N and E35Q, respectively). The mutant enzyme D52N exhibits approximately 5% of the wild-type lytic activity against Micrococcus luteus cell walls, while there is no measurable activity associated with E35Q (0.1% +/- 0.1%). The measured dissociation constants for the chitotriose-enzyme complexes were 4.1 microM (D52N) and 13.4 microM (E35Q) vs. 8.6 microM for wild type, indicating that the alterations in catalytic properties may be due in part to binding effects as well as to direct catalytic participation of these residues. The mutant lysozymes have been expressed in and secreted from yeast and obtained at a level of approximately 5 mg per liter of culture by high-salt elution from the cell walls.
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PMID:Site-directed mutagenesis of the catalytic residues Asp-52 and Glu-35 of chicken egg white lysozyme. 256 61

Bordetella pertussis Tohama phases I and III were grown to the late-exponential phase in liquid medium containing [3H]diaminopimelic acid and treated by a hot (96 degrees C) sodium dodecyl sulfate extraction procedure. Washed sodium dodecyl sulfate-insoluble residue from phases I and III consisted of complexes containing protein (ca. 40%) and peptidoglycan (60%). Subsequent treatment with proteinase K yielded purified peptidoglycan which contained N-acetylglucosamine, N-acetylmuramic acid, alanine, glutamic acid, and diaminopimelic acid in molar ratios of 1:1:2:1:1 and less than 2% protein. Radiochemical analyses indicated that 3H added in diaminopimelic acid was present in peptidoglycan-protein complexes and purified peptidoglycan as diaminopimelic acid exclusively and that pertussis peptidoglycan was not O acetylated, consistent with it being degraded completely by hen egg white lysozyme. Muramidase-derived disaccharide peptide monomers and peptide-cross-linked dimers and higher oligomers were isolated by molecular-sieve chromatography; from the distribution of these peptidoglycan fragments, the extent of peptide cross-linking of both phase I and III peptidoglycan was calculated to be ca. 48%. Unambiguous determination of the structure of muramidase-derived peptidoglycan fragments by fast atom bombardment-mass spectrometry and tandem mass spectrometry indicated that the pertussis peptidoglycan monomer fraction was surprisingly homogeneous, consisting of greater than 95% N-acetylglucosaminyl-N-acetylmuramyl-alanyl-glutamyl-diaminopimelyl++ +-alanine.
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PMID:Structure of Bordetella pertussis peptidoglycan. 288 47

Dielectric measurements have been made on lysozyme-compressed powders as a function of hydration and of the pH at which the samples were lyophilised. A dielectric dispersion previously described in the literature and known as the alpha-dispersion is found to be strongly influenced by the lyophilisation pH, and reaches a maximum magnitude at around pH 11. A dielectric loss of the form of the alpha-dispersion is observed in polylysine hydrobromide and the sodium salt of polyglutamic acid, but not for polyglycine. These results can be understood in terms of proton transfer between the ionisable side-groups, as well as by the controlling influence of counter-ions in moderating the energetics of the proton transfer processes. Another, weaker and hitherto unreported, dielectric loss process has been found for lysozyme, polyglycine, polylysine and poly(glutamic acid). This is referred to as the alpha 2-dispersion and its characteristics can be understood in terms of vibrational motions of the polypeptide backbones and the plasticising action of bound water.
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PMID:Low-frequency dielectric properties of lysozyme as a function of hydration and pH of lyophilisation. 333 53

The purpose of the present study was to give a clinical and biochemical characterization of two groups of individuals with different rates of plaque formation. From 133 individuals, 9 "heavy" and 10 "light" plaque formers were selected. The mean plaque index after 3 days of plaque accumulation, on buccal surfaces of premolars and first molars, was 2.6 for the "heavy" and 0.6 for the "light" plaque formers. The following variables were determined: periodontal status, DFS, dietary habits, salivary secretion rate and buffer effect, S. mutans and lactobacillus counts in saliva, salivary content of IgA, lactoferrin, lactoperoxidase and lysozyme, saliva-induced aggregation of certain oral streptococci, gel electrophoresis of saliva, amino acid composition of saliva and the acquired pellicle and retention depth of the dentogingival area. Comparing the two groups of plaque formers, statistically significant differences were found for the following three variables: parotid saliva-induced aggregation of a strain of S. sanguis, content of glutamic acid in the acquired pellicle and retention depth of the dentogingival area for maxillary premolars. Large variations for all studied variables were found, both within and between the groups. Several factors may be involved in plaque formation and none of the studied variables alone could explain the large difference in the amount of plaque formed after 3 days between the "heavy" and "light" plaque formers.
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PMID:Rate of plaque formation--some clinical and biochemical characteristics of "heavy" and "light" plaque formers. 347 Sep 11

In a two-step process, esterification and ammonolysis, Glu-35 and Asp-52 in lysozyme were amidated to glutamine and asparagine residues. Since the side chains of glutamine and asparagine are almost equal in size to those of glutamic acid and aspartic acid, these conversions would provide appropriate derivatives to elucidate the catalytic participations of these residues. The enzymatic activities of the resulting [Gln35]lysozyme and [Asn52]lysozyme were found to be less than 4% of that of native lysozyme in a pH range of 3.4-8.0. As these derivatives were inactive, we could determine the dissociation constants (Ks values) for the binding of beta-1,4-linked n-mer, a hexasaccharide of N-acetyl-D-glucosamine, to [Gln35]lysozyme and [Asn52] lysozyme. The values of Ks at pH 5.5 and 40 degrees C were 1.6 X 10(-5) M for [Gln35]lysozyme and 2.7 X 10(-5) M for [Asn52]lysozyme. These values are similar to that for native lysozyme. The results are direct proof for the involvements of Glu35 and Asp52 in the catalytic action of lysozyme. A method for ammonolysis of ester groups in proteins in liquid ammonia is described and will be useful for amidation of carboxyl groups of proteins.
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PMID:Chemical mutations of the catalytic carboxyl groups in lysozyme to the corresponding amides. 375 81

We studied the antigen-presenting capacity of mouse L fibroblasts transfected with genes encoding Ia polypeptides of the major histocompatibility complex (MHC). These cells function as efficient antigen-presenting cells (APC) in stimulating peptide antigen-specific MHC-restricted proliferation of long-term T-cell lines, thus establishing the capacity of Ia-expressing L-cell transfectants to present antigens to apparently normal T cells. However, in contrast to splenic APC, L-cell transfectants fail to present native hen egg-white lysozyme to the same T cells. Since this result is similar to that obtained with physiologic APC pretreated to prevent antigen degradation, it suggests that L-cell transfectants, without such pretreatments, may be compromised in their ability to process native lysozyme. However, since such transfectant cells have been shown to present other complex polypeptides such as keyhole limpet hemocyanin, a random copolymer of glutamic acid, alanine, and tyrosine, and influenza virus neuraminidase, this observation suggests that protein antigens differ in the stringency of processing requirements.
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PMID:Ia-transfected L-cell fibroblasts present a lysozyme peptide but not the native protein to lysozyme-specific T cells. 387 53


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