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)

A method for investigating the microstruct and dynamics of biological systems by means of triplet-excited molecules is suggested. The method is based on the phenomenon of triplet excitation disactivation by exchange-resonance triplet-triplet energy transfer to the acceptor or by intercombination conversion induced by interaction of an excited molecule with a paramagnetic center. The disactivation efficiency was measured by registrating the phosphorescense decay kinetics. The interaction of the triplet label eosin isothiocyanate, covalently coupled with albumine, lysozyme, sarcoplasmic reticulum membrane and Ca-Mg-dependent sarcoplasmic reticulum ATPase, with O2, the stable nitroxide radicals and ions of Mn2+ was investigated to analyse the potentialities of this method. As a model system the eosin phosphorescence quenching by the same quenchers in glycerine-aguaous solutions was studied. The method permits to investigate the microviscosity and microstructure of biological objects in the label attached region on interaction of the label with a sound-quencher with constants being 10(4) divided by 10(9) M-1 sec-1 and to measure the lateral diffusion of molecules in highly viscosity media (10 divided by 10(5) santypuas).
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PMID:[Investigation of the microstructure of biological systems by triplet label]. 22 37

The extracellular release from human neutrophils of the primary (azurophil) granule constituents, myeloperoxidase (MPO), chymotrypsin-like cationic protein (CCP), collagenase and lysozyme, and the secondary (specific) granule constituents, lactoferrin and lysozyme, was measured during ingestion of staphylococcus protein-A-IgG complexes. In buffer, lactoferrin release was consistently higher than that of the other protein. In serum, lactoferrin release increased concomitantly with ingestion, whereas the rate of lysozyme and especially of MPO release were stimulated to a higher degree than ingestion. Magnesium (0.5--2 mM) was more potent than calcium (0.5--2 mM) in promoting release but these cations worked synergistically. Zinc (0.5--4 mM) was found to be a potent and selective inhibitor of collagenase release. Manganese (0.25--4 mM), which inhibited the ingestion of SpA-IgG complexes, also inhibited release of CCP, collagenase, lysozyme and MPO, but actually stimulated lactoferrin release. The data suggests that lactoferrin and lysozyme may be confined to distinct granule populations or else released in a different fashion from the granules. When the effects on release of primary granule proteins are concerned it is suggested that the dissociation of binding of various agents to an anionic granule matrix may be affected differently by various cations.
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PMID:Effects of serum and cations on the selective release of granular proteins from human netrophils during phagocytosis. 22 47

The binding sites of Mn2+, Co2+, and Gd3+ have been determined in triclinic lysozyme at pH 4.5 to 4.6. Mn2+ and Co2+ bind a site approximately 2.5 A from 1 of the oxygen atoms of the Glu-35 chain. The occupancy of the Mn2+ site is 0.22, corresponding to 1 bound ion for each 4.6 protein molecules. The occupancy of the Co2+ site is much lower, about 0.048. Gd3+ appears to be bound at two sites, the main one 2.5 A from an oxygen atom of the Glu-35 side chain, the other 3.1 A from an oxygen atom of the Asp-52 chain. The occupancy of both Gd3+ sites is low, 0.036 and 0.016, the latter being so low that the presence of the ion at this site is in doubt. The binding site of Mn2+ in the di(N-acetylglucosamine)-lysozyme complex has also been determined. It does not differ significantly from the Mn2+ binding site in the native protein, but the occupancy is lower, 0.16.
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PMID:Metal ion binding in triclinic lysozyme. 24 Aug 35

With the glutathione system that leads to rapid regeneration of reduced lysozyme (Saxena, V. P., and Wetlaufer, D. B. (1971) Biochemistry 9, 5015), reduced pancreatic ribonuclease (RNase) regenerated activity in high yield (greater than 90%) but at a considerably lower rate (t1/2 approximately 75 min). Systematic examination of the effects upon regeneration of the concentrations and ratios of reduced and oxidized glutathione (GSH and GSSG) showed the same broad optima for RNase as were earlier found for lysozyme: [GSSG] = 5 X 10(-4) M, [GSH] = 5 X 10(-3) M. Regeneration of reduced RNase by air oxidation was shown to be inhibitable by 10(-4) M EDTA, whereas the glutathione regeneration was unaffected by EDTA. In addition the air-oxidative regeneration showed a strong temperature dependence, in contrast with the glutathione system. The mechanisms of these two kinds of regenerations are therefore different. Six potentially catalytic metal ions were tested in the air-oxidative regeneration of RNase: Cu2+, Co2+, Mn2+, Fe3+, Zn2+, and Ni2+. Of these, only Cu2+ enhanced the rate of regeneration of RNase activity, although both Cu2+ and Co2+ catalyzed thioloxidation of reduced RNase. The rates and yields of RNase regenerations were independent of protein concentration from 3 X 10(-7) M to 1.2 X 10(-5) M in the glutathione system. Preincubation of freshly dissolved reduced RNase under nonoxidizing conditions before adding glutathione did not change the rate or extent of regeneration. Studies of its pH dependence showed that the glutathione regeneration depends on the deprotonation of prototropic groups with 7.5 less than pK less than 8.0. The major ion exchange chromatographic peaks from glutathione and air-oxidative regenerations appeared to be identical with native RNase, by the criteria of specific activity, chromatographic mobility, and circular dichroic spectra. The glutathione system permits regeneration at much higher RNase concentration than the air regeneration, with rates and yields comparable to the greatest reported for air regeneration.
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PMID:Nonenzymic reactivation of reduced bovine pancreatic ribonuclease by air oxidation and by glutathione oxidoreduction buffers. 119 63

In gram-negative bacteria, numerous cell functions, including respiration-linked electron transport, have been ascribed to the cytoplasmic membrane. Gram-negative bacteria which use solid substrates (e.g., oxidized manganese or iron) as terminal electron acceptors for anaerobic respiration are presented with a unique problem: they must somehow establish an electron transport link across the outer membrane between large particulate metal oxides and the electron transport chain in the cytoplasmic membrane. When the metal-reducing bacterium Shewanella putrefaciens MR-1 is grown under anaerobic conditions and membrane fractions are purified from cells lysed by an EDTA-lysozyme-polyoxyethylene cetyl ether (Brij 58) protocol, approximately 80% of its membrane-bound cytochromes are localized in its outer membrane. These outer membrane cytochromes could not be dislodged by treatment with chaotropic agents or by increased concentrations of the nonionic detergent Brij 58, suggesting that they are integral membrane proteins. Cytochrome distribution in cells lysed by a French press protocol confirm the localization of cytochromes to the outer membrane of anaerobically grown cells. This novel cytochrome distribution could play a key role in the anaerobic respiratory capabilities of this bacterium, especially in its ability to mediate manganese and iron reduction.
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PMID:Localization of cytochromes to the outer membrane of anaerobically grown Shewanella putrefaciens MR-1. 159

We have undertaken a new and more detailed Fourier-transform infrared (FTIR) spectroscopic study of alpha-lactalbumin (in D2O solution) aimed at correlating its secondary structures to observed Amide I' infrared bands. The spectra reported here were interpreted in light of the recently determined crystal structure of alpha-lactalbumin and by comparison with the spectra and structure of the homologous protein lysozyme. Of particular importance is the new evidence supporting the assignment of the band at 1639 cm-1 to 3(10)-helices. This assignment is in excellent agreement with one based on theoretical and experimental studies of 3(10)-helical polypeptides. The frequency observed for 3(10)-helices is distinctly different from that at which alpha-helices are typically found (viz., around 1655 cm-1). In the present study, two bands are clearly resolved in the latter region at 1651 and 1659 cm-1. Both are apparently associated with alpha-helices. These results suggest that for D2O solutions of globular proteins. FTIR spectroscopy can be a facile method for detecting the presence of these two different types of helical conformation and distinguishing between them. This provides a distinct advantage over ultraviolet circular dichroism spectroscopy (UV-CD). This work also provides a basis for future studies of alpha-lactalbumin which examine the effects of environment (e.g., pH, temperature) and ligands (e.g., Ca2+, Mn2+) on its conformation.
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PMID:Infrared spectroscopic discrimination between alpha- and 3(10)-helices in globular proteins. Reexamination of Amide I infrared bands of alpha-lactalbumin and their assignment to secondary structures. 191 8

In a previous report from this laboratory (N. J. Laible and G. R. Germaine, Infect. Immun. 48:720-728, 1985), evidence was presented to suggest that the bactericidal actions of both reduced (i.e., muramidase-inactive) human placental lysozyme and the synthetic cationic homopolymer poly-D-lysine involved the activation of a bacterial endogenous activity that was inhibitable by N,N',N"-triacetylchitotriose (chitotriose). In the present investigation however, we found that the bactericidal and bacteriolytic action of poly-D-lysine could be prevented only by some commercially available chitotriose preparations and not by others. Analysis by physical and chemical methods failed to distinguish protective chitotriose (CTa) and nonprotective chitotriose (CTi) preparations. CTi and CTa preparations displayed equal capacities to competitively inhibit binding of [3H]chitotriose by immobilized lysozyme and were indistinguishable in their abilities to block the lytic activity of lysozyme against Micrococcus lysodeikticus cells. Elemental analysis revealed significantly higher levels of phosphorus, calcium, iron, sodium, manganese, and copper in CTa. Removal of metals from CTa by chelate chromatography completely abolished the poly-D-lysine-protective capacity. Of the metals detected, only ferric iron (5 to 10 microM) mimicked the protective action of CTa. A Fe(III) concentration of 50 microM was required to inhibit lysozyme (5 micrograms/ml). Both Fe(III) and CTa (but not CTi) quantitatively blocked the labeling of poly-D-lysine by fluorescamine, suggesting that the primary amino groups of the lysine residues participate in iron binding. Thus, it appears that the poly-D-lysine-protective capacity of certain chitotriose preparations was due not to the chitotriose itself but to contaminating metal ions which interact directly with the polycationic agent. In contrast, Fe(III) cannot account for inhibition of either the bactericidal or bacteriolytic activity of lysozyme by chitotriose.
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PMID:Inhibition of bactericidal and bacteriolytic activities of poly-D-lysine and lysozyme by chitotriose and ferric iron. 198 82

Two unusual characteristics of some outer membrane proteins of Rhizobium leguminosarum are described. First, most of the major outer membrane proteins could only be visualized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis after lysozyme treatment of the isolated cell envelopes, suggesting a very strong, possibly covalent, interaction of these proteins with the peptidoglycan. These peptidoglycan-associated outer membrane proteins belonged to two distinct groups of immunologically related proteins, groups II and III, as defined by typing with monoclonal antibodies. As members of both groups of proteins could be radioactively labeled by growing cells in the presence of N-[3H]acetylglucosamine, we propose that variation in the apparent molecular weight of the antigens within each group is caused by varying numbers of peptidoglycan subunit residues on only two or three different outer membrane proteins. Second, group III outer membrane proteins, with masses of 35 to 46 kilodaltons, formed oligomers stabilized by divalent cations which resisted complete denaturation in 2% sodium dodecyl sulfate at 100 degrees C. Reconstitution experiments showed that of the divalent cations tested, Ca2+ and, to a lesser extent, Mn2+ and Sr2+ were the best stabilizers.
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PMID:Evidence for divalent cation (Ca2+)-stabilized oligomeric proteins and covalently bound protein-peptidoglycan complexes in the outer membrane of Rhizobium leguminosarum. 250 Apr 20

Chrysotile asbestos is cytotoxic for rabbit polymorphonuclear leukocytes (PMNs) which is evident from the release of the cytoplasmic enzyme LDH. In the presence of Ca2+, but not in its absence, a strong lysozyme release occurs. High concentrations of Ca2+ are required for exocytosis. In the presence of the stable guanine nucleotide GTP gamma S exocytosis occurs at lower Ca2+ concentrations. The results suggest that the plasma membrane is permeabilized by asbestos, allowing the influx of extracellular Ca2+ which causes exocytosis. At high Ca2+ concentrations asbestos-induced cytotoxicity is strongly reduced. The cytotoxic LDH release and, to a lesser degree, the exocytotic enzyme release are inhibited by Co2+, Mn2+ and La3+. Cytochalasin B and the glycolytic inhibitors 2-deoxyglucose and iodoacetate inhibit asbestos-induced cytotoxicity, indicating that microfilaments and glycolytic energy are required for the membrane-damaging actions of asbestos.
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PMID:Chrysotile asbestos-induced cytotoxicity and calcium-dependent exocytosis in polymorphonuclear leukocytes. 255 37

The enthalpy change of the binding of Ca2+ and Mn2+ to equine lysozyme was measured at 25 degrees C and pH 7.5 by batch microcalorimetry: delta H degrees Ca2+ = -76 +/- 5 kJ mol-1, delta H degrees Mn2+ = -21 +/- 10 kJ mol-1. Binding constants, log KCa2+ = 6.5 +/- 0.2 and log KMn2+ = 4.1 +/- 0.5, were calculated from the calorimetric data. Therefore, delta S degrees Ca2+ = -131 +/- 20 JK-1 mol-1 and delta S degrees Mn2+ = 8 +/- 44 JK-1 mol-1. Removal of Ca2+ induces small but significant changes in the circular dichroism spectrum, indicating the existence of a partially unfolded apo-conformation, comparable with, but different from, the apo-conformation of bovine alpha-lactalbumin.
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PMID:Comparison of the binding of Ca2+ and Mn2+ to bovine alpha-lactalbumin and equine lysozyme. 260 May 98


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