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)

Synthetic vesicles were prepared by mixing anionic and cationic surfactants, aqueous sodium dodecylsulfate with didodecyltrimethylammonium or cetyltrimethylammonium bromide. The overall surfactant content and the (anionic/cationic) mole ratios allow one to obtain negatively charged vesicles. In the phase diagram, the vesicular region is located between a solution phase, a lamellar liquid crystalline dispersion, and a precipitate area. Characterization of the vesicles was performed by electrophoretic mobility, NMR, TEM, and DLS and we determined their uni-lamellar character, size, stability, and charge density. Negatively charged vesicular dispersions, made of sodium dodecylsulfate/didodecyltrimethylammonium bromide or sodium dodecylsulfate/cetyltrimethylammonium bromide, were mixed with lysozyme, to form lipoplexes. Depending on the protein/vesicle charge ratio, binding, surface saturation, and lipoplexes flocculation, or precipitation, occurs. The free protein in excess remains in solution, after binding saturation. The systems were investigated by thermodynamic (surface tension and solution calorimetry), DLS, CD, TEM, 1H NMR, transport properties, electrophoretic mobility, and dielectric relaxation. The latter two methods give information on the vesicle charge neutralization by adsorbed protein. Binding is concomitant to modifications in the double layer thickness of vesicles and in the surface charge density of the resulting lipoplexes. This is also confirmed by developing the electrophoretic mobility results in terms of a Langmuir-like adsorption isotherm. Charges in excess with respect to the amount required to neutralize the vesicle surface promote lipoplexes clustering and/or flocculation. Protein-vesicle interactions were observed by DLS, indicating changes in particle size (and in their distribution functions) upon addition of LYSO. According to CD, the bound protein retains its native conformation, at least in the SDS/CTAB vesicular system. In fact, changes in the alpha-helix and beta-sheet conformations are moderate, if any. Calorimetric methods indicate that the maximum heat effect for LYSO binding occurs at charge neutralization. They also indicate that enthalpic are by far the dominant contributions to the system stability. Accordingly, energy effects associated with charge neutralization and double-layer contributions are much higher than counterion exchange and dehydration terms.
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PMID:Protein binding onto surfactant-based synthetic vesicles. 1724 34

The volumetric response of polymer gels on cosolute addition depends on the interaction of the polymer with the cosolute and can be used as a simple and sensitive way of elucidating these interactions. Here we report on DNA networks, prepared by crosslinking double-stranded DNA with ethylene glycol diglycidyl ether (EGDE); these have been investigated with respect to their swelling in aqueous solution containing different additives, such as metal ions, polyamines, charged proteins, and surfactants. The deswelling on addition of metal ions occurs at lower concentrations with increasing valency of the counterion. The collapse of the gels in the presence of trivalent ions seems to follow the same kind of mechanism as the interaction in solution, but addition of these ions leads to DNA denaturation and formation of single-stranded DNA. Striking features were found in the deswelling of DNA gels by chitosan, spermine, spermidine, lysozyme, poly-l-lysine and poly-l-arginine. Chitosan is the most efficient cosolute of those investigated with respect to DNA gel collapse. The effect of the cationic surfactant tail length on the volume phase transition of DNA gels was studied as a function of surfactant concentration. Cationic surfactants effectively collapsed the gel from the critical aggregation concentration (cac), decreasing with increasing length of the hydrophobic tail. In several cases, the deswelling as a function of cosolute concentration shows a pronounced two-step behavior, which is interpreted in terms of a combination of DNA chain condensation and general osmotic deswelling. The studies included investigations on the state of the DNA chain after deswelling, on the reversibility of the deswelling as well as on the kinetics. With the exception for the trivalent lanthanide ions, it appears that the DNA chain always retains a double-helix conformation; with these metal ions, single-stranded DNA is found. The deswelling appears to be reversible as exemplified by addition of anionic surfactant subsequent to gel collapsed by cationic surfactant and addition of sodium bromide to gels collapsed by a polycation. An investigation of the kinetics shows that an increase in the surfactant tail length gives a pronouncedly slower deswelling kinetics.
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PMID:Effect of additives on swelling of covalent DNA gels. 1748 24

Three triblock copolymers based on the poly(lactide) or poly(lactide-co-glycolide) and poly(ethylene glycol) or poly(ethylene oxide) blocks were synthesized and characterized. The weight average molecular weight and number average molecular weight were determined by gel permeation chromatography and proton nuclear magnetic resonance spectroscopy, respectively. Fourier transform infrared spectroscopy was used to determine the completion of synthesis of polymers. Thermoreversible sol-gel transition temperature and concentration were determined by an inverted tube method. Two formulations each of three synthesized polymers containing 5% (w/v) of lysozyme or bromelain but differing in polymer concentrations (20-30%, w/v) were prepared and studied for in vitro release of the incorporated protein. In vitro biocompatibility of the delivery systems was studied by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cell viability assay. Biological activities of lysozyme and bromelain were determined by enzyme activity assays. Critical gelling concentrations were found in the range of 20-30% (w/v). In vitro biocompatibility study showed that all the formulations were biocompatible. Increasing the polymer concentration led to a decrease in burst release and extended the in vitro release of proteins. Furthermore, biological activities of lysozyme and bromelain in released samples were found to be significantly (p<0.05) greater in comparison to the control. Thus, the above thermosensitive polymers were able to deliver proteins in biologically active forms at a controlled rate for 2-8 weeks.
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PMID:Thermosensitive polymers: synthesis, characterization, and delivery of proteins. 1751 75

N-Heterocyclic cations are incorporated into proteins using 5-(2-bromoethyl)phenanthridinium bromide, which selectively reacts with either cysteine or lysine residues, resulting in ethylphenanthridinium (Phen) or highly stable cyclised dihydro-imidazo-phenanthridinium (DIP) adducts respectively; these modifications have been found to manipulate the observed structure of lysozyme and bovine serum albumin by AFM.
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PMID:Incorporation of N-heterocyclic cations into proteins with a highly directed chemical modification. 1757 44

This work examines the binding in aqueous solution, through the experimental determination of specific volumes and specific adiabatic compressibility coefficients, of decyltrimethylammonium bromide to lysozyme and to non-charged polymeric particles (which have been specially synthesized by emulsion polymerization). A method was developed to calculate the specific partial properties at infinite dilution and it was shown that a Gibbs-Duhem type equation holds at this limit for two solutes. With this equation, it is possible to relate the behavior of the partial properties along different binding types at a constant temperature. It was found that the first binding type, specific with high affinity, is related to a significant reduction of surfactant compressibility. The second binding type is accompanied by the unfolding of the protein and the third one is qualitatively identical to the binding of the surfactant to non-charged polymeric particles.
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PMID:Study of the binding between lysozyme and C10-TAB: determination and interpretation of the partial properties of protein and surfactant at infinite dilution. 1843 80

Fluorescence microscopy was used to investigate the conformational changes of individual T4 DNA molecules induced by different compacting agents, namely the cationic surfactants, cetyltrimethylammonium bromide (CTAB) and chloride (CTAC), iron(III), lysozyme, and protamine sulfate. A protocol for establishing size estimates is suggested to obtain reproducible results. Observations show that in the presence of lysozyme and protamine sulfate, DNA molecules exhibit a conformational change from an elongated coil structure to compact globules, usually interpreted as a first-order transition. The maximum degree of compaction that is attained when iron(III) or CTAB (CTAC) are used as compacting agents is considerably smaller, and intermediate structures (less elongated coils) are visible even for high concentrations of these agents. Dynamic light scattering experiments were carried out, for some of the systems, to assess the reliability of size estimates from fluorescence microscopy.
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PMID:Cationic agents for DNA compaction. 1844 12

The early intermediates in the protein aggregation pathway, the elusive soluble aggregates, play a pivotal role in growth and maturation of ordered aggregates such as amyloid fibrils. Blocking the growth of soluble oligomers is an effective strategy to inhibit aggregation. To decipher the molecular mechanisms and develop better strategies to arrest aggregation, it is imperative to understand how the size, molecular dynamics, activity and growth kinetics of soluble aggregates are affected when aggregation is inhibited. With this objective, in the present study we have investigated the influence of additives such as SDS, CTAB (cetyltrimethylammonium bromide) and DTT (dithiothreitol) on the slow aggregation of HEWL (hen eggwhite lysozyme) at pH 12.2. For this purpose, techniques such as steady-state and time-resolved fluorescence anisotropy of covalently labelled dansyl probe, gel-filtration chromatography, estimation of free thiol groups, thioflavin T and ANS (8-anilinonaphthalene-1-sulfonic acid) fluorescence, CD and atomic-force microscopy were employed to monitor the soluble oligomers over a period spanning 30 days. The results of the present study reveal that: (i) the spontaneous formation of soluble aggregates is irreversible and abolishes activity; (ii) the initial growth of aggregates (0-24 h) is promoted by a gradual increase in the exposure of hydrophobic surfaces; (iii) subsequently intermolecular disulfide bonds are critical for the assembly and stability of aggregates; (iv) the tight molecular packing inside large aggregates which contributed to slow (approximately 5 ns) and restricted segmental motion of dansyl probe was clearly loosened up in the presence of additives, enabling fast (1-2 ns) and free motion (unlike DTT, the size of lysozyme complexes with surfactants, was large, due to a conglomeration of proteins and surfactants); (v) the aggregates show reduced helical content compared with native lysozyme, except in the presence of SDS; and (vi) DTT was more potent than SDS/CTAB in arresting the growth of aggregates.
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PMID:How do surfactants and DTT affect the size, dynamics, activity and growth of soluble lysozyme aggregates? 1854 53

Purification of the total DNA extracted from activated sludge samples was studied. The effects of extraction buffers and lysis treatments (lysozyme, sodium dodecyl sulfate (SDS), sonication, mechanical mill and thermal shock) on yield and purity of the total DNA extracted from activated sludge were investigated. It was found that SDS and mechanical mill were the most effective ways for cell lysis, and both gave the highest DNA yields, while by SDS and thermal shock, the purest DNA extract could be obtained. The combination of SDS with other lysis treatment, such as sonication and thermal shock, could apparently increase the DNA yields but also result in severe shearing. For the purification of the crude DNA extract, polyvinyl polypyrrolidone was used for the removal of humic contaminants. Cetyltrimethyl ammonium bromide, potassium acetate and phenol/chloroform were used to remove proteins and polysaccharides from crude DNA. Crude DNA was further purified by isopropanol precipitation. Thus, a suitable protocol was proposed for DNA extraction, yielding about 49.9 mg (total DNA)/g volatile suspended solids, and the DNA extracts were successfully used in PCR amplifications for 16S rDNA and 16S rDNA V3 region. The PCR products of 16S rDNA V3 region allowed the DGGE analysis (denatured gradient gel electrophoresis) to be possible.
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PMID:Purification of total DNA extracted from activated sludge. 1857 27

This report describes a method for enrichment and separation of acidic and basic proteins using the centrifugal ultrafiltration followed by nanoparticle-filled capillary electrophoresis. To improve stacking and separation efficiencies of proteins, the separation buffer containing 1.6% poly(diallyldimethylammonium chloride) was added with gold nanoparticles (AuNP), poly(ethylene oxide), cetyltrimethylammonium bromide, and poly(vinyl alcohol). As a result, the use of AuNP as additives exhibited better efficiency in separation, stacking, and analysis time. Even for large-volume samples (110 nL), the separation efficiencies of acidic and basic proteins remained greater than 10(4) and 10(5) plates/m, respectively. To further enhance detection sensitivity, protein samples were enriched using the centrifugal ultrafiltration, followed by our proposed stacking method. The detection sensitivity was improved up to 314-fold compared to normal hydrodynamic injection. Additionally, the limits of detection at a signal-to-noise of 3 for most proteins were down to nanomolar range. We have validated the application of our method by means of analyses of 50 nM lysozyme in saliva samples. The proposed method was also successfully applied to the analyses of egg-white proteins, which have large differences in molecular weight and pI.
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PMID:Enrichment and separation of acidic and basic proteins using the centrifugal ultrafiltration followed by nanoparticle-filled capillary electrophoresis. 1865 38

The adsorption behavior of polycations at ionic strengths (I) ranging from 0.001 to 0.1 onto silicon wafers was studied by means of ellipsometry, contact angle measurements and atomic force microscopy (AFM). Polycations chosen were bromide salts of poly(4-vinylpyridine) N-alkyl quaternized with linear aliphatic chains of 2 and 5 carbon atoms, QPVP-C2 and QPVP-C5, respectively. Under I=0.001 the reduction of screening effects led to low adsorbed amounts of QPVP-C2 or QPVP-C5 (1.0+/-0.1 mg/m(2)), arising from the adsorption of extended chains. Upon increasing I to 0.1, screening effects led to conformational changes of polyelectrolyte chains in solution and to higher adsorbed amount values (1.9+/-0.2 mg/m(2)). Advancing contact angle theta(a) measurements performed with water drops onto QPVP-C2 and QPVP-C5 adsorbed layers varied from (45+/-2) degrees to (50+/-5) degrees, evidencing the exposure of both hydrophobic alkyl groups and charged moieties. The adsorption of lysozyme (LYZ) molecules to QPVP-C5 layers was more pronounced than to QPVP-C2 films. Antimicrobial effect of LYZ bound to QPVP-C2 or QPVP-C5 layers or to Si wafers was evaluated with enzymatic assays using Micrococcus luteus as substrates. The adsorption behavior of QPVP-C2 and QPVP-C5 at the water-air interface was studied by means of surface tension measurements. Only QPVP-C5 was able to reduce water surface tension. Mixtures of LYZ and QPVP-C5 were more efficient in reducing surface tension than pure LYZ solution, evidencing co-adsorption at liquid-air interface. Moreover, antimicrobial action observed for mixtures of LYZ and QPVP-C5 was more pronounced than that measured for pure LYZ. Hydrophobic interaction between LYZ and QPVP-C5 in solution seems to drive the binding and to preserve LYZ secondary structure.
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PMID:Lysozyme binding to poly(4-vinyl-N-alkylpyridinium bromide). 1904 Oct 95


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