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)

As an environmental protection point of view, the potential toxicity of chitosan on aquatic animal health, alone or associated with copper must be investigated. Fish possess defence mechanisms to counteract the impact of toxics. The non-cellular and non-specific immune defences (total immunoglobulin, ceruloplasmin, lysozyme and potential killing activity of phagocytic cells) can be modulated by the potential environmental pollutants but also by natural stimulants such as bacteria, viruses or parasites. In this study, we investigate the potential toxicity of copper (0.1 and 0.25 mg/L) or chitosan (75 and 150 mg/L) and the combination copper and chitosan (0.1 and 75 mg/L, respectively) on two groups of carp: healthy or parasitised by Ptychobothrium sp. Fish exposed to water-soluble chitosan for 96 h had significantly high levels of natural antibodies in plasma. Moreover, activities of lysozyme and ceruloplasmin were also increased in plasma after the same treatment. The exposition of fish to copper have shown apparently contradictory effects on the immune parameters measured but, significant increase of this bacteriolytic activity was observed, particularly in head kidney after 4 days of treatment of fish with copper. The two products may induce separately an acute, short and local inflammatory acute phase response by stimulating some components of the innate immune response of healthy fish. The mixture seems to reduce the impact of the each product due to the physical and chemical properties of chitosan to complex with copper. The responses of humoral immune factors of treated carp was modulated by the presence of the parasite, as shown by the high elevation of lysozyme activity observed in parasitised carps after exposition to copper and by increases in natural antibodies levels observed in parasitised carp treated with the copper-chitosan mixture. This could indicate an additive effect on the stress response mediated by parasite. It occurred a greater stress response in the parasitised group than healthy group exposed to the same treatment evoking an additive effect. So, it is important to specify the health status of organisms to understand responses of immunological markers in fish.
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PMID:Humoral immune factors modulated by copper and chitosan in healthy or parasitised carp (Cyprinus carpio L.) by Ptychobothrium sp. (Cestoda). 1517 50

The macrocyclic antiviral drug xylyl-bicyclam blocks entry of HIV into cells by targeting the CXCR4 coreceptor, a seven-helix transmembrane G-protein-coupled receptor. Its affinity for CXCR4 is enhanced by binding to Cu2+, Ni2+, or Zn2+. Metallocyclams have a rich configurational chemistry and proteins may bind selectively to specific metallocyclam configurations. Our studies of lysozyme reveal structural details of protein-metallocyclam interactions that are important for receptor recognition. Solution NMR studies show that Cu-cyclam interacts with specific tryptophan residues of lysozyme (Trp-62, Trp-63, and Trp-123). Two major binding sites for both Cu-cyclam and Cu2-xylyl-bicyclam were detected by x-ray crystallography. In the first site, Cu2+ in one cyclam ring of Cu2-xylyl-bicyclam adopts a trans configuration and is coordinated to a carboxylate oxygen of Asp-101, whereas for Cu-cyclam two ring NH groups form H bonds to the carboxylate oxygens of Asp-101, stabilizing an unusual cis (folded) cyclam configuration. For both complexes in this site, a cyclam ring is sandwiched between the indole side chains of two tryptophan residues (Trp-62 and Trp-63). In the second site, a trans cyclam ring is stacked on Trp-123 and H bonded to the backbone carbonyl of Gly-117. We show that there is a pocket in a model of the human CXCR4 coreceptor in which trans and cis configurations of metallobicyclam can bind by direct metal coordination to carboxylate side chains, cyclam-NH...carboxylate H bonding, together with hydrophobic interactions with tryptophan residues. These studies provide a structural basis for the design of macrocycles that bind stereospecifically to G-coupled and other protein receptors.
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PMID:Protein recognition of macrocycles: binding of anti-HIV metallocyclams to lysozyme. 1570 2

To design artificial proteases that cleave peptide backbones of a wide range of proteins at selected sites, artificial active sites comprising the Cu(II) complex of cyclen (Cu(II)Cyc) and aldehyde group were synthesized on a cross-linked polystyrene. The aldehyde group was employed as the binding site in view of its ability of reversible formation of imine bonds with epsilon-amino groups of Lys residues exposed on the surface of proteins and Cu(II)Cyc as the catalytic group for peptide hydrolysis. The two polymeric artificial metalloproteases synthesized in the present study cleaved all of the protein substrates examined (myoglobin, gamma-globulin, bovine serum albumin, human serum albumin, lysozyme, and ovalbumin), manifesting saturation kinetic behavior. At 50 degrees C and pH 9.0 or 9.5, K(m) was (1.3-22) x 10(-)(4) M, comparable to those of natural proteases, and k(cat) was (6.0-25) x 10(-)(4) s(-)(1), corresponding to half-lives of 4.6-19 min. Intermediacy of the imine complexes formed between the aldehyde group of the catalyst and the epsilon-amino groups of Lys residues of the substrates was confirmed by the trapping experiment with NaB(OAc)(3)H. MALDI-TOF MS of the proteolytic reaction mixtures revealed formation of various cleavage products. Structures of some of the cleavage products were determined by using carboxypeptidase A and trypsin. Among various cleavage sites thus identified, Gln(91)-Ser(92) and Ala(94)-Thr(95) were the major initial cleavage sites in the degradation of myoglobin by the two catalysts. The selective cleavage of Gln(91)-Ser(92) and Ala(94)-Thr(95) was attributed to general acid assistance in peptide cleavage by Tyr(146) located in proximity to the two peptide bonds. Broad substrate selectivity, high cleavage-site selectivity, and high proteolytic rate are achieved, therefore, by positioning the aldehyde group in proximity to Cu(II)Cyc attached to a cross-linked polystyrene.
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PMID:Artificial metalloprotease with active site comprising aldehyde group and Cu(II)cyclen complex. 1598 87

A novel lysozyme was purified from a marine microorganism and its major characteristics were studied. Cell-free supernatant was prepared by centrifugation of culture broth, ultrafiltration using a hollow fiber (molecular weight cut off, 50kD) and concentration using a hollow fiber (molecular weight cut off, 10kD). The crude lysozyme was purified 34.7 fold to electrophoretic homogeneity with a recovery of 24.1% by CM-Sepharose FF cationic-exchange and Sephadex G-100 gel chromatography. The relative molecular weight of this lysozyme was determined as about 39 kD. The optimum pH and temperature towards Micrococcus lysodleikticus were pH 8.0 and 35 degrees C respectively, and the enzyme was stable at temperature below 50 degrees C and pH 5.0 - 10.0. The lysozyme activity was slightly enhanced by Zn2+ and Cu2+ and slightly inhibited by Mn2+ and Ag+. The lysozyme showed good compatibility to many common chemical agents such as EDTA (0.1%) and KH2 PO4 (1.0%). The lysozyme had broad-spectrum against many bacteria, including a number of pathogens, which were resistant to egg-white lysozyme.
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PMID:[Purification and characterization of a lysozyme from a marine microorganism]. 1610 67

Silica particles of different porosity were functionalised with iminodiacetic acid (IDA) and loaded with Cu(II) ions to yield Cu(II)-IDA-silica. These immobilised metal affinity chromatography (IMAC) materials were subjected to a comprehensive characterisation study. The Cu(II) content--determined via UV/Vis spectroscopy and atomic absorption spectroscopy (AAS)--was found to be linearly dependent on the specific surface area of the silica particles. The evaluation of protein adsorption isotherms provided information on binding properties towards biomolecules. The data fitted Langmuir's adsorption theory. Binding capacity of hen egg white lysozyme (HEWL) was highest for Cu(II)-IDA-silica with mean pore diameter of 120 A, reaching nearly 350 mg/g. All derivatised materials were applied to the fractionation of human serum samples and subsequent mass spectrometric analysis (m/z: 2000-10,000) according to a surface-enhanced affinity capture (SEAC) protocol. Pore size of the support material affected the appearance of the mass spectra to a great extent, showing that surface morphology is another parameter that has to be considered in addition to surface chemistry. Signal intensity as well as the number of detected masses were strongly dependent on the pore diameter, indicating that the carrier material has to be carefully chosen to assure best results.
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PMID:Cu(II)-loaded iminodiacetic acid-silica particles for protein profiling of human serum samples using surface-enhanced affinity capture: support porosity effects. 1625 43

Bacteriolytic enzyme R1 was purified to electrophoretic homogeneity with the recovery of 6.89% activity by ammonium sulfate precipitation, CM-Sephadex C - 50, CM-Sepharose Fast Flow and Sephadex G-75 chromatography from the culture supernatant of Streptomyces griseus RX-17. The molecular weight and PI of R1 were 16.8 kD and 9.10. The optimal temperature and pH for R1 against Streptococcus mutans Ingbritt were 70 degrees C and 6.6, respectively. Below 50 degrees C and at range pH 6 - 10, R1 was stable. While treated at 60 degrees C for 1 hour, the residual activity was only about 20.3%. Zn2+, Cu2+, Fe2+, Cd2+ and Pb2+ could completely inactivate the enzyme. Chelating agents, hydroxylamine hydrochloriae, Monoiodoacetic acid inhibited the lytic activity against Streptococcus mutans Ingbritt, whereas Mg2+, 2-Mercaptoethanol and some surfactants could stimulate the activity. The enzyme had a broad bacteriolytic spectrum against many G+, G- bacteria which were resistant to egg-white lysozyme. Especially high activity was shown on Streptococcus mutans, Staphylococcus aureus and Lactobaillus.
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PMID:[Purification and some properties of bacteriolytic enzyme R1 from Streptomyces griseus RX-17]. 1627 98

The present study evaluated whether blood could be used as a nondestructive tool for monitoring metal exposure and related hematological effects in wood mice (Apodemus sylvaticus L.) living along a metal pollution gradient. Soil concentrations of arsenic, cadmium, copper, lead, silver, and zinc decreased with distance from the emission source. Blood levels of cadmium and lead differed significantly among sites, whereas those of the other metals did not. Blood levels of cadmium and lead correlated with soil concentrations of cadmium and lead, respectively. No such significant relationships were found for the other measured metals. Hematocrit levels decreased in wood mice from the most polluted site (45.96% +/- 0.53% [mean +/- standard error]) compared to the reference site (48.04% +/- 0.47%). A negative correlation between hematocrit and blood levels of cadmium and lead was found. Erythrocyte count, leukocyte count, hemoglobin concentration, mean corpuscular hemoglobin (average wt of hemoglobin in a red blood cell in pg), and lysozyme activity did not differ among study sites. Mean corpuscular volume (average volume of a red blood cell in microm3) and mean corpuscular hemoglobin concentration (average proportion of hemoglobin in a red blood cell as a %) differed among study sites but showed no relationship with metal exposure. We conclude that whole blood from mice can be used for nondestructive monitoring of the exposure to nonessential metals under natural conditions. The present results indicate that decreased hematocrit levels may be an early warning signal for a negative impact of metal exposure on the oxygen-transport capacity of blood in wood mice in their natural environment.
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PMID:Metal blood levels and hematological characteristics in wood mice (Apodemus sylvaticus L.) along a metal pollution gradient. 1649 36

Immobilized metal-chelate affinity chromatography has been widely used in the purification of proteins, and we have recently found that it can also be applied to purification of nucleic acids through interactions involving exposed bases, especially purines. Here we report that the inclusion of moderate quantities of neutral solutes in the buffer substantially enhances the binding affinity of nucleic acids for immobilized metal-chelate affinity adsorbents. Addition of 20% (v/v) of solutes such as ethanol, methanol, isopropanol, n-propanol, and dimethyl sulfoxide enhances the initial affinity of binding of total yeast RNA by 4.4-, 3.8-, 3.7-, 3.0-, and 2.8-fold, respectively for Cu(II)-iminodiacetic acid (IDA) agarose adsorbent, and the weaker adsorption by Cu(II)-nitrilotriacetic acid (NTA) agarose was even more strongly enhanced. The adsorption affinities of the smaller oligodeoxynucleotide molecules A20, G20, C20 and T20 also increase with the addition of ethanol, suggesting that the effect is not significantly mediated by conformational changes. Binding enhancement generally correlates with reduction of water activity by the various solutes, as predicted by several models of solution thermodynamics, consistent with an entropic contribution by displacement of waters from the metal-chelate. Interestingly, the enhancement was not seen with the proteins bovine serum albumin and lysozyme.
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PMID:Neutral additives enhance the metal-chelate affinity adsorption of nucleic acids: role of water activity. 1660 Feb 63

Polymeric coatings with high protein-binding capacities are important for increasing the output of affinity-based protein purification and decreasing the detection limits of antibody microarrays. This report describes the use of thick poly(acrylic acid) (PAA) brushes to immobilize as much as 80 monolayers of protein. The brushes were prepared using a recently developed procedure that allows polymerization of 100-nm-thick poly(tert-butyl acrylate) films from a surface in just 5 min along with hydrolysis of these films to PAA in 15 min. Covalent binding of bovine serum albumin (BSA) to PAA brushes that were activated using standard coupling agents, however, resulted in immobilization of less than two monolayers of BSA because of competitive hydrolysis of the esters in the activated film. In contrast, derivatization of PAA with nitrilotriacetate (NTA)-Cu2+ complexes yielded films capable of binding many monolayers of protein via metal-ion affinity interactions. For example, derivatization of 55-nm-thick PAA films with NTA-Cu2+ allowed immobilization of about 15 monolayers (5.8 microg/cm2 or 58 nm) of BSA. The binding capacity was even higher for myoglobin (7.7 microg/cm2) and anti-IgG (9.6 microg/cm2). Remarkably, electrostatic adsorption of lysozyme in 55-nm-thick, underivatized PAA resulted in as much as 80 monolayers (16.2 microg/cm2 or 162 nm) of adsorbed protein. Polymer synthesis, derivatization, and swelling, as well as BSA immobilization kinetics and thermodynamics were characterized using reflectance FT-IR spectroscopy, ellipsometry, and protein assays.
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PMID:High-capacity binding of proteins by poly(acrylic acid) brushes and their derivatives. 1661 75

A two-dimensionally tunable focusing monochromator has been developed for protein crystallography at high-energy undulator beamlines of third-generation synchrotron radiation facilities. This monochromator consists of a silicon wafer fabricated with an oblique-cut angle between the Bragg net plane and the crystal surface, and adhered onto a table-like copper block. The radii of curvatures are altered independently in two directions by expanding the spaces between the table legs. The versatilities of the meridional and sagittal curvatures were confirmed by X-ray experiments and three-dimensional shape measurements, respectively. The two-dimensional focusing ability was demonstrated using high-energy X-rays of 37.7 keV emitted from a bending-magnet source at the Photon Factory. A quasi-isotropic profile of converged X-rays was achieved near the focal position. The apparent gain of photon flux was 21. As a result of these excellent monochromator characteristics, a diffraction pattern of a hen egg-white lysozyme crystal was successfully obtained using high-energy X-rays.
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PMID:Development of a two-dimensionally tunable focusing monochromator for protein crystallography at high-energy undulator beamlines. 1670 59


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