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)

Sensitivity to lysozyme of the representatives of various species of gramnegative microflora (476 strains) was studied with a new modified procedure, which is more exact and economic as compared to the method of serial dilutions in agar. High resistance of Eltor vibrio cholerae and Pseudomonas to lysozyme was found. Cultures of various sensitivity levels to lysozyme were detected among Aeromonas, enteropathogenic E. coli and NAG-vibrios.
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PMID:[Sensitivity of Gram-negative microflora to lysozyme]. 38 35

Hen egg white lysozyme was the first enzyme whose structure was determined by X-ray crystallography. The proposed mechanism based on this structure involves the distortion of the saccharide residue (2-acetamido-2-deoxy-D-muramic acid, NAM) in the natural substrate (an alternating beta (1 leads to 4) linked oligomer of 2-acetamido-2-deoxy-D-glucose (NAG) and NAM residues) bound to site D in the binding cleft. The importance of substrate distortion has prompted numerous enzymatic, chemical, theoretical, and physical studies, but there is little direct crystallographic evidence on the conformation of a NAM residue bound at site D. We now present the X-ray structure of the non-hydrolysed trisaccharide NAM-NAG-NAM bound in subsites B, C, D. Our interpretation of the 2.5-A resolution difference map does not involve distortion of this residue in site D. Comparison with the structure of the delta-lactone derived from tetra N-acetylchitotetraose (NAG)3NAL) bound to lysozyme suggests we may be looking at a Michaelis complex.
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PMID:X-ray crystallography of the binding of the bacterial cell wall trisaccharide NAM-NAG-NAM to lysozyme. 51 67

The pressure-induced reversible unfolding of lysozyme was investigated by high-resolution proton magnetic resonance spectroscopy by following the proton spectra of the following residues: His-15 epsilon 1, Trp-28 epsilon 3, Leu-17 delta 2, Cys-64 alpha, and Trp-108 epsilon 3. The experiments were performed at pH 3.9 and 68.5 degrees C in the pressure range from 1 bar to 5 kbar both in the absence and presence of tri-N-acetylglucosamine (tri-NAG). From the pressure-induced changes of the equilibrium between the native and denatured forms of lysozyme, the reaction volumes (delta V) were calculated for each residue. Small but statistically significant differences in delta V were found for residues located in different regions of the protein. For example, delta V for the disulfide bonded Cys-64 alpha is smaller than the delta V's found for the other residues. In particular, the effect of tri-NAG binding to lysozyme was a change of delta V from -10.3 +/- 0.6 cm3/mol to -18.1 +/- 1.7 cm3/mol for the Trp-108 epsilon 3 residue which is located close to the active site. It is important to note that the Cys-64 alpha residue also senses the binding of the substrate analog. The ability to detect statistically significant differences for delta V of individual residues located in different regions of lysozyme represents the main result of these experiments.
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PMID:High-resolution NMR study of the pressure-induced unfolding of lysozyme. 151 Sep 63

A structure of the trisaccharide 2-acetamido-2-deoxy-D-muramic acid-beta (1----4)-2-acetamido-2-deoxy-D-glucose-beta (1----4)-2-acetamido-2-deoxy-D-muramic acid (NAM-NAG-NAM), bound to subsites B, C and D in the active-site cleft of hen egg-white lysozyme has been determined and refined at 1.5 A resolution. The resulting atomic co-ordinates indicate that the NAM residue in site D is distorted from the full 4C1 chair conformation to one in which the ring atoms C-1, C-2, O-5 and C-5 are approximately coplanar, and the hydroxymethyl group is positioned axially (a conformation best described as a sofa). This finding supports the original proposals that suggested the ground-state conformation of the sugar bound in site D is strained to one that more closely resembles the geometry required for the oxocarbonium-ion transition state, the next step along the reaction pathway. Additionally, detailed analysis at 1.5 A resolution of the environments of the catalytic residues Glu35 and Asp52 provides new information on the properties that may allow lysozyme to promote the stabilization of an unusually long-lived oxocarbonium-ion transition state. Intermolecular interactions between the N-acetylmuramic acid residue in site D and the lysozyme molecule that contribute to the saccharide ring distortion include: close packing of the O-3' lactyl group with a hydrogen-bonded "platform" of enzyme residues (Asp52, Asn46, Asn59, Ser50 and Asp48), a close contact between the hydroxymethyl group of ring D and the 2'-acetamido group of ring C and a strong hydrogen-bonded interaction between the NH group of Val109 and O-6 of ring D that stabilizes the observed quasi-axial orientation of the -CH2OH group. Additionally, the structure of this complex shows a strong hydrogen bond between the carboxyl group of Glu35 and the beta-anomeric hydroxyl group of the NAM residue in site D. The hydrogen-bonded environment of Asp52 in the native enzyme and in the complex coupled with the very unfavorable direction of approach of the potential carboxylate nucleophile makes it most unlikely that there is a covalent glycosylenzyme intermediate on the hydrolysis pathway of hen egg-white lysozyme.
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PMID:Lysozyme revisited: crystallographic evidence for distortion of an N-acetylmuramic acid residue bound in site D. 185 65

The stabilization of the folded conformation of lysozyme, arising from the binding of the inhibitor (NAG)3 against induced denaturation, is demonstrated from the 1H-nmr spectra of the enzyme. The nmr spectra reveal that the binding of the denaturant (GuHCl) to the enzyme is associated with changes in the conformation of the enzyme. The binding site of the inhibitor site C also serves as one of the binding sites of GuHCl. The observation that higher denaturant concentrations are required in the unfolding of Lys-(NAG)3 as compared to free Lys can be explained partly in terms of the existence of a competitive binding to the enzyme involving the (NAG)3 and GuHCl molecules.
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PMID:NMR studies on the induced denaturation of lysozyme by guanidine hydrochloride in the presence of the inhibitor (NAG)3. 259 39

Nephritic functionality has been studies, making use of same nephritic enzymes dosage (NAG, AAP, alpha-glucosidase, lysozyme) in three groups of workers (varnishers, metallurgists, plastic manufacture employees) professionally exposed to nephritic damage, and in a control group made up of not professionally exposed to the same hazard subjects. The aim was to precociously detect possible nephritic damage, i.e. before classic nephritic functionality indexes were distorted. An increased enzymuria appeared in those subjects that were exposed to nephrotoxic hazard. Increased enzymuria have been found in only one subject of the control group. We deem it should be useful, to customarily measure out nephritic enzymes as trusted index of tabular damage, in hiring and pensionary control examinations.
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PMID:[Evaluation of damage in subjects exposed to nephrotoxic substances]. 290 71

The activity of NAG, lysozyme and PMN-elastase has been investigated in the superior vena caval and left atrium blood collected from patients who underwent open heart surgery. The effect of various types of respiration on the enzyme release has been also documented. Concentration gradients between v. cava sup. and left atrium has been used as an index for pulmonary damage post operatively. We found a time dependent increase of all enzymes during extracorporeal circulation. However, only the release of NAG and lysozyme is characteristic for pulmonary damage. We observed significant higher enzyme release from the lung after Apnea ventilation compared with the PEEP and low frequency ventilation group. Also significant higher NAG and lysozyme activity was found in patients who needed longer respiration post-operatively. PMN-elastase seems to be not suitable for diagnosis of post perfusion lung because the main amount of elastase released by mechanical destroy of the granulocytes.
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PMID:Biochemical monitoring of the lung during and after extracorporeal circulation. 364 23

Random urine samples were obtained to evaluate potential age- or urine concentration-related differences in lysozyme or NAG content. The concentration and excretion of both enzymes was widely variable although no age-related differences were seen. Urine concentration, however, was an important variable as NAG concentration (per mL urine) and lysozyme excretion (per mumol creatinine) were significantly elevated and reduced, respectively, in samples with a higher specific gravity. The correlation coefficient between urine specific gravity and both parameters was significant. Lysozyme excretion is elevated in subjects undergoing a modest diuresis although NAG excretion is unaffected. These data may prove to be useful in the evaluation of renal dysfunction.
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PMID:The effects of age and urine concentration on lysozyme and N-acetyl-beta-D-glucosaminidase (NAG) content in urine. 378 36

In experiments in vitro dioxidineeee was highly effective as regards all the test cultures of NAG-vibrios. The MTC ranged within 1 to 62 micrograms/ml. Bactericidal action of the drug became manifest at concentrations from 4 to 250 micrograms/ml. The derivatives of di-N-oxide quinoxaline, dioxidin and quinoxidine exerted a chemotherapeutic effect and sterilizing action in experimental NAG-infection. The action of the drugs was potentiated upon combined use with lysozyme. As far as depo-sulfanilamides are concerned, sulfalenee was little active, while sulfamonomethoxine ineffective in experimental NAG-infection.
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PMID:[Activity of di-N-hydroxyquinoxaline and depot-sulfanilamide derivatives in experimental NAG infection]. 709 14

In the first section the assay methods of lysozyme are reviewed. It is pointed out that there is no method using the hydrolysis of NAM- > beta-1, 4-glycoside bond- > NAG, So to clarify relation between methods will lead to discovery of new isozymes. In the second chapter serum or urinary lysozyme levels are discussed in the states of diseases. The high levels are induced by cell proliferation which are producing lysozyme. The type of cells and their nature may infer different lysozymes that has no clear evidences yet. In the third part lysozyme is reviewed as protein and product of gene. In the final, enzyme kinetics are the subject of investigation, and further studies may by chance conduct us to find out new isozymes of lysozyme in near future.
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PMID:[Lysozyme]. 760 80


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