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)

Using immunoenzymatic reactions (ELISA) with MDA-crosslinked lysozyme (ML) or poly-L-lysine (MP) and with the corresponding native protein or polypeptide, we showed that sera from normal human subjects contain immunoglobulins with antibody-like specificity for MDA-modified proteins. Inhibition studies with ML and MP showed that the chemical structures recognized by these immunoglobulins include 1-amino-3-iminopropene (AIP) bridges resulting from reactions of MDA with primary amino groups. An ELISA technique for quantitation of these immunoglobulins was developed and applied to 32 sera from healthy humans, which provided an estimation of their normal levels. Variations of these levels under pathological conditions are now being investigated.
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PMID:Immunological relevance of malonic dialdehyde (MDA): III. Immuno-enzymatic determination of human immunoglobulin binding to MDA-crosslinked proteins. 342 85

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

We have studied the effect of neutralizing the surface charge of rat glomerular epithelial cells (GEC) in culture on prostanoid production. Incubation of rat GEC with polycations poly-L-lysine (PL) resulted in a dose dependent increase of 6-keto-PGF1 alpha (up to 8 to 10-fold) and PGE2 (up to 7 to 8-fold) production. Other polycations such as protamine sulfate (PS) and lysozyme (LY) produced a similar effect. The stimulation of prostaglandin (PG) production by PL treated GEC was prevented by the addition of polyanions such as bovine serum albumin (BSA) and heparin (HP). The effect of PL on prostaglandin (PG) synthesis by GEC was suppressed by the cyclooxygenase inhibitor sulindac sulfide. Addition of exogenous arachidonic acid (C20:4) increased the basal production of PG and under these conditions the effect of PL was masked. We conclude that neutralization of the surface charge of rat GEC by polycations results in profound increase of prostanoid synthesis. The polycation caused increase in PG synthesis appears to be the result of increased availability of intracellular C20:4.
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PMID:Glomerular epithelial cell, polyanion neutralization is associated with enhanced prostanoid production. 362

Salt solutions and charged detergents are efficient solubilizing agents for ovovitelline membrane lysozyme. Reassociation experiments with chemically modified lysozymes indicate that positively charged amino acid residues of lysozyme (the epsilon-amino group of lysine and the guanidino group of arginine) are involved in the interaction with other proteins of the vitelline membrane. Exogenous proteins are adsorbed to lysozyme-free vitelline membranes, only if they have a high pI, comparable to that of lysozyme. It is concluded that the lysozyme-ovovitelline membrane interaction is predominantly ionic. An ovomucin-lysozyme complex is postulated as the major component of the outer layer of the membrane.
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PMID:Mode of interaction between lysozyme and the other proteins of the hen's egg vitelline membrane. 374 71

This study was conducted to assess the relative accuracy of five different assay techniques for the determination of protein concentration in human mixed saliva. The protein concentration of paraffin-stimulated saliva from 20 individuals was determined using the biuret reaction, the Lowry assay, a modified Lowry technique using bicinchoninic acid, and two dye-binding assays. Using bovine serum albumin as the standard, mean values ranged from 0.67 to 2.37 mg/ml. The use of bovine serum albumin, trypsinogen, lysozyme, bovine pancreatic ribonuclease, and poly-L-lysine as standards with the five different assay techniques to measure protein concentration of pooled mixed saliva from the above subjects produced results ranging from 0.74 to 65.5 mg/ml. The protein concentration obtained for this saliva sample by amino acid analysis was consistent with the value obtained for the biuret reaction using any of the five different standard proteins. Thus, the protein concentration obtained for human saliva depends upon both the technique used and the protein standard.
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PMID:Comparison of five techniques for the determination of protein content in mixed human saliva. 382 22

The basis of the bactericidal activity of human lysozyme against Streptococcus sanguis was studied. Experiments were designed to evaluate the role of lysozyme muramidase activity in its bactericidal potency. Inactivation of the muramidase activity of lysozyme was achieved by reduction of essential disulfides with dithiothreitol (DTT) or by incubation with the chitin oligosaccharides chitotriose and chitobiose. Muramidase-inactive lysozyme, prepared by reduction with DTT, was equal in bactericidal potency to native lysozyme. Solutions of native chicken egg white lysozyme and human lysozyme exhibited equal bactericidal potency yet differed ca. fourfold with respect to lytic (muramidase) activity. The above results suggested that the bactericidal activity of lysozyme is not dependent upon muramidase activity. Chitotriose and chitobiose were found to inhibit both lytic and bactericidal activities of lysozyme. The bactericidal activity of muramidase-inactive lysozyme (reduction with DTT) was also inhibited by chitotriose and chitobiose. Further investigations demonstrated that chitotriose and chitobiose were also potent inhibitors of the bactericidal activity of the cationic homopolypeptides poly-L-arginine and poly-D-lysine. These latter results suggested that the essential bactericidal property of lysozyme was its extreme cationic nature and that some bacterial endogenous activities, inhibitable by chitotriose and chitobiose, were essential for expression of the bactericidal activity of either native or muramidase-inactive lysozyme or of the cationic homopolypeptides. Experiments with Streptococcus faecalis whole cells, cell walls, and crude autolysin preparations implicated endogenous autolytic muramidases as the bacterial targets of chitotriose and chitobiose. The essentially identical responses of S. sanguis and S. faecalis to chitotriose in bactericidal assays with muramidase-inactive lysozyme and polylysine suggested that muramidase-like enzymes exist in S. sanguis and, furthermore, play an essential role in cationic protein-induced loss of viability of the oral microbe.
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PMID:Bactericidal activity of human lysozyme, muramidase-inactive lysozyme, and cationic polypeptides against Streptococcus sanguis and Streptococcus faecalis: inhibition by chitin oligosaccharides. 392 94

The effects of basic and neutral amino acids on the reabsorption of 125I-lysozyme by the renal proximal tubule were examined in rats. In whole animal experiments control animals were given an intravenous (i.v.) injection of 125I-lysozyme alone while experimental animals received an i.v. injection of either a basic or a neutral amino acid prior to the injection of 125I-lysozyme. In control animals the renal content of 125I-lysozyme 30 min after injection was 35% of the injected dose. After injection of basic amino acids there was a significant decrease in the renal uptake of lysozyme. There was no effect of neutral amino acids on the reabsorption of lysozyme. In microperfusion experiments proximal convoluted tubules were perfused in vivo for 3 min with a solution containing 125I-lysozyme and either lysine or alanine. In tubules perfused with lysine there was a significant decrease in the reabsorption of lysozyme, whereas alanine had no effect on lysozyme uptake. Electron microscope autoradiography revealed that lysozyme was located in endocytic vesicles and lysosomes in both experimental groups. However, the autoradiographic grain density was significantly decreased in tubules perfused with lysine as compared with those perfused with alanine. These findings demonstrate that basic amino acids inhibit the reabsorption of the cationic protein lysozyme by the proximal tubule cells.
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PMID:Inhibition of protein reabsorption in the renal proximal tubule by basic amino acids. 399 85

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

The cationic polyamino acids polylysine and polyarginine cause a time and concentration dependent lysis of rabbit polymorphonuclear leukocytes. Lysis, measured as LDH release, is preceded by exocytosis, as can be deduced from a higher lysozyme release than LDH release, at short incubation time or with low concentrations of polylysine. The lytic effect of polylysine could be annihilated with the polyanion polyglutamic acid. Monomeric lysine or arginine, or low-molecular-weight polylysine, were not lytic. This indicates that positive charges on a polymeric molecule of sufficient chain length play a predominant role in the interaction. Substances that promote exocytosis cause an increase of lysozyme release and a reduction of LDH release, whereas inhibitors of exocytosis cause the reverse: less lysozyme release and more LDH release. Negatively charged sialic groups on the plasma membrane are not important for the interaction, because their removal does not affect the lytic effect of polylysine on the cell. The possibility that the lipid part of the plasma membrane is the point of attack for the polycations is discussed.
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PMID:Cytolytic effect of polylysine on rabbit polymorphonuclear leukocytes. 404 28

The binding of dapsone to hen egg white lysozyme has been studied using fluorescence spectroscopy. At low concentrations the drug binds lysozyme with a Ka = 3.3 X 10(4) M-1 forming a 1:1 complex. At high concentrations the protein was found to bind the drug in a cooperative manner at two sites with an average association constant of 6.3 X 10(4) M-1. Both Trp-108 and Trp-62 of lysozyme are involved in the association process. Acetylation of the lysine residues increased the affinity of the drug to the protein. However, drug association showed no effect on the enzymatic activity of the protein.
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PMID:Chemical characterization of the dapsone binding site of lysozyme. 404 63


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