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)

Some urinary enzymes (NAG, AAP, lysozyme) considered to be sufficiently sensitive and reliable markers of renal damage were controlled in 20 patients with cirrhosis of the liver and in 20 healthy control subjects. The results, stated as mean +/- SD, showed a statistically very significant increase (p < 0.01) of NAG and lysozyme in cirrhotics. Furthermore, this increase could be at least in part related with the seriousness of clinical condition. On the basis of these results, we think the urinary dosage of NAG and lysozyme is, in the subjects with liver cirrhosis, a bloodless method to show an early renal damage.
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PMID:[Urinary enzymes in liver cirrhosis: useful early markers of renal damage?]. 791 12

In order to reveal the origin of carbohydrate recognition specificity of human lysozyme by clarifying the difference in the binding mode of ligands in the active site, the inactivation of human lysozyme by 2',3'-epoxypropyl beta-glycoside derivatives of the disaccharides, N,N'-diacetylchitobiose [GlcNAc-beta-(1-->4)-GlcNAc] and N-acetyllactosamine [Gal-beta-(1-->4)-GlcNAc], was investigated and the three-dimensional structures of the affinity-labeled enzymes were determined by X-ray crystallography at 1.7 A resolution. Under the conditions comprising 2.0 x 10(-3) M labeling reagent and 1.0 x 10(-5) M human lysozyme at pH 5.4, 37 degrees C, the reaction time required to reduce the lytic activity against Micrococcus luteus cells to 50% of its initial activity was lengthened by 3.7 times through the substitution of the nonreducing end sugar residue, GlcNAc to Gal. The refined structure of human lysozyme labeled by 2',3'-epoxypropyl beta-glycoside derivatives of N,N'-diacetylchitobiose (HL/NAG-NAG-EPO complex) indicated that the interaction mode of the N,N'-diacetylchitobiose moiety in substites B and C in this study was essentially the same as in the case of the complex of human lysozyme with the free ligand. On the other hand, the hydrogen-bonding pattern and the stacking interaction at subsite B were remarkably different between the HL/NAG-NAG-EPO complex and human lysozyme labeled by the 2',3'-epoxypropyl beta-glycoside of N-acetyllactosamine (HL/GAL-NAG-EPO complex). The reduced number of possible hydrogen bonds as well as the less favorable stacking between the side chain of Tyr63 in human lysozyme and the galactose residue in the HL/GAL-NAG-EPO complex reasonably explained the less efficient ability of the 2',3'-epoxypropyl beta-glycoside of N-acetyllactosamine as compared to that of N,N'-diacetylchitobiose as an affinity labeling reagent toward human lysozyme.
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PMID:Origin of carbohydrate recognition specificity of human lysozyme revealed by affinity labeling. 888 35

We constructed a system for the expression and secretion of mature hen lysozyme by yeast using an intermediate "secretion-signal cassette" vector, pKP1700, containing the yeast invertase signal sequence and an expression vector, pAM82, for secretion and maturation of the enzyme. Using this system, mutants of hen lysozyme were produced and the catalytic mechanism in hen lysozyme was definitely confirmed. The hydrolytic activity of D52A as to substrate (NAG)6 at pH 5.0 was obviously decreased to one-four hundredth of that of the wild type. The acidic limb of the pH-activity profile observed for the wild-type was not observed for D52A, and the pKa of Glu 35 on the alkaline limb was seen for both enzymes. Moreover, no structural change was detected on X-ray analysis of D52A. Therefore, we confirmed that dissociated Asp 52 assists catalysis by producing an electrostatic field and by stabilizing the oxocarbonium ion intermediate in the dissociated form.
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PMID:A mutation study of catalytic residue Asp 52 in hen egg lysozyme. 890 88

Time domain dielectric measurements were applied to the monitoring of molecular recognition by proteins. Lysozyme and tri-N-acetyl-D-glucosamine((NAG)3) were selected as a typical lock and key type recognition system. After association of (NAG)3, relaxation related to lysozyme itself was increased and depended on the pH of the solution. No change was detected in hydration of the enzyme before and after association.
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PMID:Dielectric measurements of lysozyme and tri-N-acetyl-D-glucosamine association at radio and microwave frequencies. 945 86

Chicken egg white lysozyme is progressively inhibited by diazoacetyl-DL-norleucine methyl ester (DANME) and by chlorambucil at concentrations of 3.4 x 10(-3) M and 5 x 10(-3) M respectively over a three-hour time period. DANME inhibits lysozyme activity to the extent of 87%, and chlorambucil inhibits the enzyme to the extent of 93%. N,N',N"-triacetylchitotriose [(NAG)3], which binds to subsites A, B and C of the enzyme protects lysozyme from DANME inhibition to the extent of 40% of the total activity when added to the enzyme at a concentration of 3.6 x 10(-3) M prior to the addition of DANME. (NAG)3 protects the enzyme from inhibition by chlorambucil to the extent of 14% of the total activity when added to the enzyme at a concentration of 5.6 x 10(-3) M prior to the addition of chlorambucil. Since DANME reacts exclusively with carboxyl groups, and since aspartic acid 101 is required for binding the carbohydrate substrate at site A, it is suggested that (NAG)3 may bind reversibly to the active site of the enzyme, thereby protecting aspartic acid 101 from esterification by DANME and subsequent inactivation. Chlorambucil, which may react with carboxyl, amino, imidazole and thiol groups, more likely acts upon a larger number of susceptible sites, thereby causing irreversible alkylation and conformation changes. As a bifunctional alkylating agent, it may also cross-link with two available nucleophiles. The K(m) for lysozyme with M. lysodeikticus as a substrate in wholly aqueous medium was determined to be 0.05 mg/mL. The inhibitor exhibits a partially uncompetitive upon pre-incubation with the enzyme, and a mixed inhibition between competitive and noncompetitive when pre-incubated with the substrate.
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PMID:The effect of chlorambucil upon lysozyme activity. 1002 96

A mutant lysozyme where R14 and H15 are deleted together has higher activity and a similar binding ability to an inhibitor, trimer of N-acetylglucosamine ((NAG)3), compared with wild-type lysozyme. Since this has been attributed to intrinsic protein dynamic properties, we investigated the relationship between the activity and the internal motions of proteins. Backbone dynamics of the free and the complex forms with the (NAG)3 have been studied by measurement of the 15N T1 and T2 relaxation rates and NOE determinations at 600 MHz. Analysis of the data using the model-free formalism showed that the generalized order parameters (S2) were almost the same in wild-type and mutant lysozyme in unbound state, indicating that the mutation had little effect on the global internal motions. On the other hand, in the presence of (NAG)3, although some signals located around the active site were broadened or decreased in intensity because of strong perturbation by (NAG)3, there were several residues that showed increased or decreased backbone S2 in the complexed lysozymes. A comparison of the internal motions of the wild-type and mutant complexes showed a number of distinct dynamic differences between them. In particular, many residues located at or near active-site regions (turn 1, strand 2, turn 2 and long loop), displayed greater backbone dynamics reflecting the order parameter in mutant complex relative to mutant free. Furthermore, the Rex values at the loop C-D region, which was considered to be important for enzymatic activity, significantly increased. From these results, it was suggested that variations in the dynamics of these regions may play an important role in the enzyme activity.
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PMID:Analysis of the relationship between enzyme activity and its internal motion using nuclear magnetic resonance: 15N relaxation studies of wild-type and mutant lysozyme. 1006 15

The synergism between apolar and polar interactions in the carbohydrate recognition by human lysozyme (HL) was probed by site-directed mutagenesis and affinity labeling. The three-dimensional structures of the Tyr63-->Leu mutant HL labeled with 2',3'-epoxypropyl beta-glycoside of N,N'-diacetylchitobiose (L63-HL/NAG-NAG-EPO complex) and the Asp102-->Glu mutant HL labeled with the 2',3'-epoxypropyl beta-glycoside of N-acetyllactosamine were revealed by X-ray diffraction at 2.23 and 1.96 A resolution, respectively. Compared to the wild-type HL labeled with the 2', 3'-epoxypropyl beta-glycoside of N,N'-diacetylchitobiose, the N-acetylglucosamine residue at subsite B of the L63-HL/NAG-NAG-EPO complex markedly moved away from the 63rd residue, with substantial loss of hydrogen-bonding interactions. Evidently, the stacking interaction with the aromatic side chain of Tyr63 is essential in positioning the N-acetylglucosamine residue in the productive binding mode. On the other hand, the position of the galactose residue in subsite B of HL is almost unchanged by the mutation of Asp102 to Glu. Most hydrogen bonds, including the one between the carboxylate group of Glu102 and the axial 4-OH group of the galactose residue, were maintained by local movement of the backbone from residues 102-104. In both structures, the conformation of the disaccharide was conserved, reflecting an intrinsic conformational rigidity of the disaccharides. The structural analysis suggested that CH-pi interactions played an important role in the recognition of the carbohydrate residue at subsite B of HL.
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PMID:Protein-carbohydrate interactions in human lysozyme probed by combining site-directed mutagenesis and affinity labeling. 1063 Sep 88

Peptidoglycan of Streptococcus lactis SB900(LABPG) was isolated. It's chemical composition was analyzed and part of biological activity was examined. The PG contained 9.84% protein, 0.871 mumol/m NAG, 1.14 mumol/mg NAM. The amino acids of relatively high concentrations were Ala, Glu, Asp and their concentrations were 1.046, 0.775, 0.304 mumol/mg respectively. Using mice as subject, the animal experiment confirmed that LABPG was non-toxic and safe. Effect of i.p. LABPG 0.5 mg/mouse on the phagocytic function were studied. It was suggested that the phagocytic activity of PM phi had markedly enhanced, the activity of serum lysozyme was increased significantly. YC-Rosette experiment suggested that the activity of C3b receptors of PM phi were increased and the YC-Rosette forming ratio were higher than controls. The difference was significant by statistical analysis. Therefore, it is considered that LABPG was able to activate M phi and improve immune function in mice.
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PMID:[Part of biological activity of peptidoglycan from Streptococcus lactis SB900]. 1254 2

Understanding the mechanisms of the interaction between a protein surface and its outer molecular environment is of primary relevance for the rational design of new drugs and engineered proteins. Protein surface accessibility is emerging as a new dimension of Structural Biology, since NMR methods have been developed to follow how molecules, even those different from physiological ligands, preferentially approach specific regions of the protein surface. Hen egg-white lysozyme, a paradigmatic example of the state of the art of protein structure and dynamics, has been selected as a model system to study protein surface accessibility. Bound water and soluble spin-labels have been used to investigate the interaction of this enzyme, both free and bound to the inhibitor (NAG)(3), with its molecular environment. No tightly bound water molecules were found inside the enzyme active site, which, conversely, appeared as the most exposed to visits from the soluble paramagnetic probe TEMPOL. From the presented set of data, an integrated view of lysozyme surface accessibility towards water and TEMPOL molecules is obtained.
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PMID:NMR studies of protein hydration and TEMPOL accessibility. 1294 93

The application of a novel method for the identification of low-molecular-weight noncovalent ligands to a macromolecular target is reported. This technique is based on the measurement of analyte diffusion coefficients by electrospray mass spectrometry (ESI-MS) (Clark et al., Rapid Commun. Mass Spectrom. 2002, 16, 1454-1462). Potential ligands have large diffusion coefficients as long as they are free in solution. Binding to a macromolecular target, however, drastically reduces the diffusional mobility of any ligand species. Mixtures containing six different saccharides [ribose, rhamnose, glucose, maltose, maltotriose, and N,N',N''-triacetylchitotriose (NAG(3))] were screened for noncovalent binding to lysozyme. Of these six compounds, only NAG(3) is known to bind to the protein. In "direct" binding tests, NAG(3) shows a significantly reduced diffusion coefficient in the presence of the protein. No changes were observed for any of the other saccharides. In a second set of experiments, the use of a "competition" screening method was explored in which mixtures of candidate saccharides were tested for their ability to displace a reference ligand from the target. The addition of NAG(3)-containing mixtures significantly increased the diffusion coefficient of the reference ligand NAG(4) (N,N',N'',N'''-tetraacetylchitotetrose), whereas mixtures that did not contain NAG(3) had no effect. These data clearly indicate the potential of ESI-MS-based diffusion measurements as a novel tool to screen compound libraries for binding to proteins and other macromolecular targets. In contrast to conventional ESI-MS-based ligand-receptor binding studies, this method does not rely on the preservation of noncovalent interactions in the gas phase.
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PMID:Screening for noncovalent ligand-receptor interactions by electrospray ionization mass spectrometry-based diffusion measurements. 1498 79


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