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 kinetics of the photodynamic desactivation of lysozyme in presence of acridine orange as the sensitizer have been investigated in detail varying oxygen, protein, dye concentration, ionic strength and pH value. The kinetics can be approximately described as an over all pseudo-first-order rate process. Changing the solvent from water to D2O or by quenching experiments in presence of azide ions it could be shown that the desactivation of lysozyme is caused exclusively by singlet oxygen. The excited oxygen occurs via the triplet state of the dye with a rate constant considerably lower than that to be expected for a diffusionally controlled reaction. Singlet oxygen react chemically (desactivation, k=2.9 X 10(7) m(-1) sec(-1)) and physically (quenching process, k=4.1 X 10(8) m(-1) sec(-1)) with the enzyme. The kinetical analysis shows that additional chemical reaction between singlet oxygen and lysozyme would have only little influence on the kinetics of the desactivation as long as their products would be enzymatically active and their kinetical constants would be less than about 1 X 10(8) m(-1) sec(-1)).
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PMID:On the mechanism of the acridine orange sensitized photodynamic inactivation of lysozyme. I. Basic kinetics. 0 28

Thylakoid membranes were prepared from the blue-green alga, Anacystis nidulans with lysozyme treatment and a short period of sonic oscillation. The thylakoid membrane preparation was highly active in the electron transport reactions such as the Hill reactions with ferricyanide and with 2,6-dichlorophenolindophenol, the Mehler reaction mediated by methyl viologen and the system 1 reaction with methyl viologen as an electron acceptor and 2,6-dichlorophenolindophenol and ascorbate as an electron donor system. The Hill reaction with ferricyanide and the system 1 reaction was stimulated by the phosphorylating conditions. The cyclic and non-cyclic phosphorylation was also active. These findings suggest that the preparation of thylakoid membranes retained the electron transport system from H2O to reaction center 1, and that the phosphorylation reaction was coupled to the Hill reaction and the system 1 reaction.
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PMID:Photosynthetic electron transport and phosphorylation reactions in thylakoid membranes from the blue-green alga Anacystis nidulans. 2 96

The identification and complete assignment of the C-2 and N-1 proton nuclear magnetic resonances (NMR) of the six tryptophan residues of hen lysozyme are reported. Identification of the resonances required a detailed examination of the spectra of the protein in H2O and in 2H2O, and involved the application of spin-echo and Carr-Purcell-Meiboom-Gill pulse sequences. Assignment was achieved by observing the effects on the NMR spectra of performing specific chemical modifications, of binding paramagnetic species (lanthanide ions and spin labels), of binding inhibitors and protons and of carrying out solvent exchange experiments. The problems involved in completion of assignment are fully discussed. In the course of performing experiments to make assignments, several interesting aspects of the behaviour of the tryptophan residues in the protein structure were observed and are discussed.
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PMID:Study of the tryptophan residues of lysozyme using 1H nuclear magnetic resonance. 3 40

Hen egg white lysozyme has been prepared in which the C epsilon position of the single histidine residue is substituted by a deuterium atom as a nondisturbing stable isotope probe. The deuterium nuclear magnetic resonance (2H NMR) spectrum in H2O shows a broad resonance (500--1000 Hz) due to the histidine deuteron and a sharp signal from residual HOD. The line width of the deuterium signal increases with pH, reflecting the self-association of lysozyme which is known to involve this histidine [shindo, H., Cohen, J.S., & Rupley, J. A. (1977) Biochemistry 16, 3879]. Correlation times calculated from spin-spin relaxation times (T2) derived from the 2H widths indicate that His-15 is restricted in motion and that lysozyme is predominantly dimerized at pH 7.5. Controls carried out with [epsilon-2H]imidazole showed a small pH dependence of the spin-lattice relaxation time (T1), which parallels the 2H chemical shift change upon ionization of the imidazole. Similar results cannot generally be observed by proton nuclear magnetic resonance (1H NMR) because of paramagnetic relaxation due to trace metal ion impurities. The pH dependence of the 2H T1 values indicates a change in the 2H quadrupole coupling constant upon protonation of the imidazole ring.
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PMID:Protein mobility and self-association by deuterium nuclear magnetic resonance. 3 94

30 patients on long-term lithium therapy have been studied. The results are presented of the urinary concentrating ability after water deprivation and the intranasal administration of vasopressin, of the simultaneous determination of glomerular filtration rate (GFR) and effective renal plasma flow (ERPF), of the minimal urine pH after an oral dose of ammonium chloride, and of the urinary beta-2-microglobulin excretion. Mean urine concentration (+/- SEM) after 22 hr water deprivation (= Uosm) amounted to 854 +/- 22 mOsm/kg H2O, mean GFR was 101 +/- 4 ml/min, mean ERPF 360 +/- 18 ml/min, and mean minimal urine pH 4.95 +/- 0.06. In 8 out of 30 patients there was polyuria. In these 8 patients the values were 778 +/- 51 mOsm/kg H2O, 113 +/- 6 ml/min, 415 +/- 33 ml/min and 4.99 +/- 0.08, respectively. Serum levels of beta-2-microglobulin and lysozyme and the urinary excretion of beta-2-microglobulin were normal in all patients. No correlation was established between Uosm and the serum lithium concentration during the test (0.8 +/- 0.05 mmoles/l) nor between Uosm and the average serum lithium level during treatment (0.79 +/- 0.03). GFR was only correlated with age. It was found that administration of indomethacin during the concentration test increased Uosm in these patients. The results suggest that, given proper dosage and surveillance, long-term treatment with lithium is not likely to cause disturbances in renal function.
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PMID:A renal function study in 30 patients on long-term lithium therapy. 4 7

In the studies presented the effective procedure of isolation and purification of enterobacterial common antigen from Shigella sonnei has been elaborated. The method is based on sonification of bacterial suspension in the presence of lysozyme and EDTA and subsequent extraction of the pellet with boiling water. The crude extract of common antigen was purified by fractionation with ethanol and chromatography on silica gel and Sephadex LH-20. The comparison of several extraction procedures of enterobacterial common antigen from Shigella sonnei proved that the method described above is most effective. The purified enterobacterial common antigen preparation obtained preserved full biological activity: antigenicity (precipitation and activity in enzyme-linked immunosorbent assay), immunogenicity in rabbits, ability to coat erythrocytes (passive hemagglutination) and inhibitory activity in passive hemagglutination. The pure enterobacterial common antigen was identified to 90% as a polymer of N-acetyl-D-mannosaminuronic acid and N-acetyl-D-glucosamine (2:1, molar ratio), O-acetylated and containing 3.2% fatty acids (C16:0 and C18:1, not oleic). It contains 5.3% nitrogen, less than 4% protein, less than 0.5% phosphorus and less than 1.6% neutral sugar; glycerol and RNA were not found in the preparation.
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PMID:Enterobacterial common antigen: isolation from Shigella sonnei, purification and immunochemical characterization. 10 11

The most common cyanobacterium contaminating drinking water systems in southwestern Pennsylvania is Schizothrix calcicola. Lipoplysaccharides (LPS) were isolated from this species by hot phenol-water extraction. The polysaccharide moiety was composed of glucosamine, galactose, glucose, mannose, xylose and rhamnose. The lipid A part contained beta-hydroxylauric, myristic, pentadecanoic, palmitic, beta-hydroxypalmitic, stearic, oleic, and linoleic acids. In contrast to many LPS isolated from Enterobacteriaceae, the dominant component was not beta-hydroxymyristic but beta-hydroxypalmitic acid. The LPS induced Limulus lysate gelation and Schwartzman reaction but was nontoxic to mice. The identity of LPS was verified by alkali and lysozyme treatment. The results suggest that S. calcicola is one of the principal sources of endotoxins in water systems using open finished-water reservoirs.
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PMID:Composition and biological properties of lipopolysaccharides isolated from Schizothrix calcicola (Ag.) Gomont (Cyanobacteria). 11 86

Genetic, endocrine and immunological factors are probably involved in adjuvant polyarthritis. The nature of the vehicle and of the mycobacterial components administered also has a major influence. It was originally assumed that arthritogenicity and adjuvanticity of mycobacterial fractions such as wax D were intimately related. Our previous findings showed that the water soluble adjuvant (WSA) of M.smegmatis which could substitute for mycobacterial cells in Freund's complete adjuvant and induce delayed hypersensitivity was not arthritogenic in the Wistar rat. We have since observed that auto-immune diseases could be elicited by WSA. Therefore experiments were repeated using the very susceptible Lewis strain. The activity of cord factor and of various mycobacterial preparations suspended in mineral or in peanut oil was also evaluated in mice and in normal or hypophysectomized rats. Our present findings confirm the absence of arthritogenicity of WSA in the Lewis strain. They also indicate that cord factor with WSA does not suffice to induce a generalized adjuvant disease, but that a mycobacterial component which could be susceptible to lysozyme treatment is required also. However, the local inflammation of the injected limb was produced by a preparation of cord factor administered in mineral or even in peanut oil. This was observed in normal or hypophysectomized rats and in Swiss mice which were not susceptible to the generalized disease.
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PMID:Adjuvant disease induced by mycobacteria, determinants of arthritogenicity. 18 72

The phases of simple systems involving one type of protein (lysozyme or cytochrome c) and one type of lipid (phosphatidic acid) have been characterized by X-ray crystallography, chemical analysis and spin-labeling technique as a function of temperature. They are of the lamellar type with alternative protein monolayers and lipid bilayers. According to the pH, two types of lamellar phases are obtained, one where the lipid-protein interactions are mainly hydrophobic, the other where they are electrostatic. In both cases, a phase transition occurs as temperature is lowered, between a high temperature phase, where all the lipids are in the liquid-like state, and another phase where some lipid chains are rigid. In the case of the phases with electrostatic interaction, it is shown that the onset of the order-disorder transition is shifted towards low temperature as compared with the homologous lipid-water phase and that the protein content of the phase decreases as the ratio of the liquid to rigid hydrocarbon chains decreases. This leads us to suggest that in the systems studied in this work the proteins interact only with lipid in the liquid-like state. In the case of the phases with hydrophobic interaction, it is shown that the extent of hydrophobic interaction between protein and lipid increases as the unsaturation of the hydrocarbon chains increases. The onset of the order-disorder transition shows a greater shift towards low temperature than the one observed in the case of the phase with electrostatic interaction.
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PMID:The influence of protein-lipid interactions on the order-disorder conformational transitions of the hydrocarbon chain. 20 47

H+ titration curves of hen egg-white lysozyme were obtained at 0.15 I in the presence of small amounts (less than 15%) of methanol, ethanol and n-propanol. The acidity constants of two groups (whose pK values in water are, respectively, 42 and 3.5) are increased in water-alcohol mixtures in comparison to water. From the evaluation of these constants as a function of alcohol concentration and hydrocarbon chain length, it is suggested that these alcohols interact specifically with lysozyme. As pK values of 4.2 and 3.5 in water are generally assigned to Asp-101 and Asp-52 respectively, it seems that interaction occurs within the active site of the enzyme.
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PMID:Hydrogen ion titration of lysozyme in alcohol-water solutions. 24 Apr 38


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