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)

As a practical contribution to an understanding of the usefulness of measuring some electrolytes in urine, the author first recalls that elements measured in a 24-h urine sample provide nutritional informations, whereas those assayed in fasting morning urine generate data on renal tubular function. To illustrate the first point the author describes assessment of the etiology of hypercalciuria based on a knowledge of concomitant 24-h excretions of sodium, phosphate, urate and creatinine. On the second point, the author suggests dissociating the parameters of which only the urinary concentration is of interest (pH, lysozyme, gamma-glutamyl-transferase) from the parameters of which the excretion--either fractional (Na, K, Cl, P, Mg) or absolute (Ca)--should be calculated. Finally, the reader is reminded how to use the nomogram of Peacock, Robertson and Nordin to evaluate fasting urinary excretion of calcium, and how to use the nomogram of Walton and Bijvoet to estimate the renal threshold phosphate concentration.
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PMID:[Usefulness of urinary electrolyte determination]. 356 52

The glycation (nonenzymatic glycosylation) of several proteins was studied in various buffers in order to assess the effects of buffering ions on the kinetics and specificity of glycation of protein. Incubation of RNase with glucose in phosphate buffer resulted in inactivation of the enzyme because of preferential modification of lysine residues in or near the active site. In contrast, in the cationic buffers, 3-(N-morpholino)propane-sulfonic acid and 3-(N-tris(hydroxymethyl)methyl-amino)-2-hydroxypropanesulfonic acid, the kinetics of glycation of RNase were decreased 2- to 3-fold, there was a decrease in glycation of active site versus peripheral lysines, and the enzyme was resistant to inactivation by glucose. The extent of Schiff base formation on RNAse was comparable in the three buffers, suggesting that phosphate, bound in the active site of RNase, catalyzed the Amadori rearrangement at active site lysines, leading to the enhanced rate of inactivation of the enzyme. Phosphate catalysis of glycation was concentration-dependent and could be mimicked by arsenate. Phosphate also stimulated the rate of glycation of other proteins, such as lysozyme, cytochrome c, albumin, and hemoglobin. As with RNase, phosphate affected the specificity of glycation of hemoglobin, resulting in increased glycation of amino-terminal valine versus intrachain lysine residues. 2,3-Diphosphoglycerate exerted similar effects on the glycation of hemoglobin, suggesting that inorganic and organic phosphates may play an important role in determining the kinetics and specificity of glycation of hemoglobin in the red cell. Overall, these studies establish that buffering ions or ligands can exert significant effects on the kinetics and specificity of glycation of proteins.
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PMID:Effect of phosphate on the kinetics and specificity of glycation of protein. 358 12

The structure of the lysozyme from bacteriophage T4 has been refined at 1.7 A resolution to a crystallographic residual of 19.3%. The final model has bond lengths and bond angles that differ from "ideal" values by 0.019 A and 2.7 degrees, respectively. The crystals are grown from electron-dense phosphate solutions and the use of an appropriate solvent continuum substantially improved the agreement between the observed and calculated structure factors at low resolution. Apart from changes in the conformations of some side-chains, the refinement confirms the structure of the molecule as initially derived from a 2.4 A resolution electron density map. There are 118 well-ordered solvent molecules that are associated with the T4 lysozyme molecule in the crystal. Four of these are more-or-less buried. There is a clustering of water molecules within the active site cleft but, other than this, the solvent molecules are dispersed around the surface of the molecule and do not aggregate into ice-like structures or pentagonal or hexagonal clusters. The apparent motion of T4 lysozyme in the crystal can be interpreted in terms of significant interdomain motion corresponding to an opening and closing of the active site cleft. For the amino-terminal domain the motion can be described equally well (correlation coefficients approx. 0.87) as quasi-rigid-body motion either about a point or about an axis of rotation. The motion in the crystals of the carboxy-terminal domain is best described as rotation about an axis (correlation coefficient 0.80) although in this case the apparent motion seems to be influenced in part by crystal contacts and may be of questionable relevance to dynamics in solution.
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PMID:Structure of bacteriophage T4 lysozyme refined at 1.7 A resolution. 358 19

Human airway lysozyme, purified from pathological bronchial secretions, is characterized by a specific activity 3-fold higher than that of hen egg-white lysozyme. The amino acid composition of human airway lysozyme is identical to that of other human lysozymes. The laser Raman spectra of human airway lysozyme and hen egg-white lysozyme in phosphate buffer solution (pH 7.2) are recorded in the range 300-1900 cm-1 at 488 nm. Drastic intensity differences are observed between the spectra analyzed in the ranges characteristic of the peptide backbone (e.g., beta-sheet; C alpha-C, C alpha-N), and of the aromatic side-chain vibrations (tyrosine, tryptophan). The deconvolution of the Raman amide I band gives secondary structures of 38% and 39% alpha-helix, 25% and 20% beta-sheet, and 37% and 41% undefined structure for the human and hen lysozymes, respectively.
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PMID:Characterization and conformational analysis by Raman spectroscopy of human airway lysozyme. 369 62

Lysozyme is an important resistance factor in the respiratory defence mechanism. Few reports exist concerning its effects on the ciliary activity of the human nasal mucosa. To clarify the biological activity of lysozyme in ciliary movement, a quantitative study was undertaken using a photo-electrical method to measure ciliary beats in vitro under conditions of constant temperature. Egg-white lysozyme in a 0.01 M sodium phosphate buffer solution, pH 7.4, dose-dependently accelerated the ciliary beats in the human nasal mucosa, removing overlying mucus continuously for at least 60 min. The buffer alone, however, failed to affect ciliary beats. These results indicate that egg-white lysozyme directly promotes the ciliary beats in the human nasal mucosa.
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PMID:Promotive effect of lysozyme on the ciliary activity of the human nasal mucosa. 370 54

Two strains of rumen anaerobes isolated from dehydrodivanillin-degrading cultures were identified as Fusobacterium varium and Enterococcus faecium. These organisms degraded dehydrodivanillin synergistically to 5-carboxymethylvanillin and vanillic acid. Specific conditions for protoplast formation and cell wall regeneration for both bacteria were determined, under strictly anaerobic conditions, to be as follows. The cell wall of each bacterium in yeast extract medium was loosened by adding penicillin G during early log-phase growth. The cell wall of F. varium was lysed by lysozyme (1 mg/ml) in glycerol (0.2 M)-phosphate buffer (0.05 M; pH 7.0). The addition of NaCl (0.08 M) with lysozyme was necessary for lysis of E. faecium in this solution. Almost all cells were converted to protoplasts after 2 h of incubation at 37 degrees C. Regeneration of both protoplasts was 20 to 30% on an agar-containing yeast extract medium.
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PMID:Protoplast formation and regeneration of dehydrodivanillin-degrading strains of Fusobacterium varium and Enterococcus faecium. 377 21

Both resting and paraffin-stimulated whole saliva were studied in 25 patients with fissured tongue and in their age and sex-matched healthy controls. The groups did not differ in dental or periodontal health. No significant differences were found between the groups in the salivary secretion rate, pH and buffer capacity, or in the frequency of lactobacilli and yeasts in saliva samples and scrapings from tongue surface. In patients with fissured tongue, unstimulated whole saliva displayed significantly elevated levels of sodium, lysozyme, myeloperoxidase and all immunoglobulins (isotypes A, G and M) when compared with the controls. These changes most likely reflect the inflammation frequently seen in the biopsies of fissured tongue. No differences between the groups existed in the amounts of salivary potassium, calcium, inorganic phosphate, amylase and total protein. Our study shows that in patients with fissured tongue the salivary secretion and composition are normal. However, components from plasma and inflammatory cells are diagnostically elevated in the whole saliva samples of patients with fissured tongue when compared with the healthy controls.
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PMID:Changes in composition of whole saliva in patients with fissured tongue. 386 14

The structure of the linkage unit between ribitol teichoic acid and peptidoglycan in the cell walls of Listeria monocytogenes EGD was studied. A teichoic-acid--glycopeptide preparation isolated from lysozyme digests of the cell walls of this strain contained mannosamine, glycerol, glucose and muramic acid 6-phosphate in an approximate molar ratio of 1:1:2:1, together with large amounts of glucosamine and other components of teichoic acid and glycopeptides. A teichoic-acid-linked sugar preparation, obtained by heating the cell walls at pH 2.5, also contained glucosamine, mannosamine, glycerol and glucose in an approximate molar ratio of 25:1:1:2. Part of the glucosamine residues were shown to be involved in the linkage unit. Thus, on mild alkaline hydrolysis, the teichoic-acid-linked sugar preparation gave a disaccharide characterized as N-acetylmannosaminyl(beta 1----4)-N-acetylglucosamine [ManNAc(beta 1----4)GlcNAc] in addition to the ribitol teichoic acid moiety, whereas the teichoic-acid - glycopeptide was separated into disaccharide-linked glycopeptide and the ribitol teichoic acid moiety by the same procedure. Furthermore, Smith degradation of the cell walls gave a characteristic fragment, EtO2-P-Glc(beta 1----3)Glc(beta 1----1/3)Gro-P-ManNAc(beta 1----4)GlcNAc (where EtO2 = 1,2-ethylenediol and Gro = glycerol). The results lead to the conclusion that in the cell walls of this organism, the ribitol teichoic acid chain is linked to peptidoglycan through a novel linkage unit, Glc(beta 1----3)Glc(beta 1----1/3)Gro-P-(3/4)ManNAc-(beta 1----4)GlcNAc.
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PMID:Characterization of a novel linkage unit between ribitol teichoic acid and peptidoglycan in Listeria monocytogenes cell walls. 391 62

Previously described methods for measuring human tear lysozyme are fraught with shortcomings. A new method has been devised. Tear fluid was collected on Whatman filter paper discs. Each disc was placed in a tightly capped tube containing sodium phosphate buffer. Fluid from each tube was placed directly into a well of the lysozyme immunodiffusion plate. After the precipitation rings had reached maximum size, their diameters were measured. A linear standard curve was constructed, and lysozyme concentration was expressed as micrograms per milliliter. The tear lysozyme concentration was obtained from the standard curve and corrected for the assay dilution factor. The mean tear lysozyme concentration in 15 normal patients was 1.4 +/- 0.5 mg/mL. In ten patients with dry eyes, the mean was 0.7 +/- 0.5 mg/mL. The method used to collect, store, and transport tears is easily performed in the clinic and readily tolerated by patients. The technique of radial immunodiffusion is reliable and simple, compared with other assays.
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PMID:An improved method for measuring human tear lysozyme concentration. 391 95

The cell wall of Bacillus subtilis is capable of binding different kinds of metal ions. The wall-ion complex appears to be dependent on both phosphoryl from teichoic acid and carboxylate from peptidoglycan. In the present study, cationized ferritin (CF) was used as a probe for charge distribution on the wall of B. subtilis 168. Detergent-extracted cell walls bound CF only on the outer wall face. Completed cell poles bound CF, but septa did not. When the walls were permitted to autolyze briefly, binding of CF occurred on both faces. In contrast, limited hydrolysis of the walls by egg white lysozyme resulted in the penetration of CF into the wall matrix. When walls were made teichoic acid-free, CF-binding asymmetry was preserved, suggesting that carboxyl groups were oriented toward the surface. Walls with carboxylates chemically neutralized also retained charge asymmetry. Phosphate-free and carboxyl-modified walls bound CF only poorly or not at all. These results indicate that negative charges contributed by both phosphate and carboxyl are responsible for the binding of CF and that the observed asymmetry in the distribution of the label is due to the orientation of teichoic acid and muramyl peptides toward the outside of the cell wall, above the plane of the glycan strands.
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PMID:Asymmetric distribution of charge on the cell wall of Bacillus subtilis. 392 97


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