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 series of proteins and one membrane-bound peptide have been partitioned in aqueous two-phase systems consisting of micelle-forming block copolymers from the family of Pluronic block copolymers as one polymer component and dextran T500 as the other component. The Pluronic molecule is a triblock copolymer of the type PEO-PPO-PEO, where PEO and PPO are poly(ethylene oxide) and poly(propylene oxide), respectively. Two different Pluronic copolymers were used, P105 and F68, and the phase diagrams were determined at 30 degrees C for these polymer systems. Since the temperature is an important parameter in Pluronic systems (the block copolymers form micellar-like aggregates at higher temperatures) the partitioning experiments were performed at 5 and 30 degrees C, to explore the effect of temperature-triggered micellization on the partitioning behaviour. The temperatures correspond to the unimeric (single Pluronic chain) and the micellar states of the P105 polymer at the concentrations used. The degree of micellization in the F68 system was lower than that in the P105 system, as revealed by the phase behaviour. A membrane-bound peptide, gramicidin D, and five different proteins were partitioned in the above systems. The proteins were lysozyme, bovine serum albumin, cytochrome c, bacteriorhodopsin and the engineered B domain of staphylococcal protein A, named Z. The Z domain was modified with tryptophan-rich peptide chains in the C-terminal end. It was found that effects of salt dominated over the temperature effect for the water-soluble proteins lysozyme, bovine serum albumin and cytochrome c. A strong temperature effect was observed in the partitioning of the integral membrane protein bacteriorhodopsin, where partitioning towards the more hydrophobic Pluronic phase was higher at 30 degrees C than at 5 degrees C. The membrane-bound peptide gramicidin D partitioned exclusively to the Pluronic phase at both temperatures. The following trends were observed in the partitioning of the Z protein. (i) At the higher temperature, insertion of tryptophan-rich peptides increased the partitioning to the Pluronic phase. (ii) At the lower temperature, lower values of K were observed for ZT2 than for ZT1.
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PMID:Aqueous two-phase systems containing self-associating block copolymers. Partitioning of hydrophilic and hydrophobic biomolecules. 1032 23

Nonspecific protein adsorption generally occurs at the biomaterial-tissue interface and usually has adverse consequences. Thus, surfaces that are protein-resistant are eagerly sought with the expectation that these materials will exhibit improved biocompatibility. Surfaces modified with end-tethered poly(ethylene oxide) (PEO) have been shown to be protein-resistant to some degree. Although the mechanisms are unclear, it has been suggested that chain length, chain density, and chain conformation are important factors. To investigate the effects of PEO chain density, we selected a model system based on the chemisorption of chain-end thiolated PEO to a gold substrate. Chain density was varied by varying PEO solubility (proximity to cloud point) and incubation time in the chemisorption solution. The adsorption of fibrinogen and lysozyme to these surfaces was investigated. It was found that for 750 and 2000 MW PEO layers, resistance to fibrinogen increased with chain density and was maximal at a density of approximately 0.5 chains/nm(2) (80% decrease in adsorption compared to unmodified gold). As PEO chain density increased beyond 0.5/nm(2) adsorption increased. For PEO of 5000 MW the optimal chain density was 0.27/nm(2) and gave only a 60% reduction in fibrinogen adsorption. It is suggested that, at high chain density, the chemisorbed PEO is dehydrated giving a surface that is no longer protein resistant. The PEO-modified surfaces were found also to be resistant to lysozyme adsorption with reductions similar to, if somewhat less than, those for fibrinogen. The fibrinogen to lysozyme molar ratios were within the expected range for close-packed layers of these proteins in their native conformation and were relatively insensitive to PEO chain density and MW. This may suggest that such adsorption as did occur, even at chain densities giving minimum adsorption, may have been on patches of unmodified gold.
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PMID:Protein resistance of surfaces prepared by sorption of end-thiolated poly(ethylene glycol) to gold: effect of surface chain density. 1566 86

Silicone-based polymers with reduced protein adsorption were successfully prepared by incorporating mono- or bifunctional poly(ethylene oxide) (PEO) derivatives, respectively, into PDMS during rubber formation using classic room temperature vulcanization chemistry. Characterization of the films by water contact-angle measurements and XPS showed that the PEO was present on the film surface, with greater amounts of PEO at the interface modified with monofunctional PEO. Scanning electron microscopy showed the PEO domains segregated into regular zigzag patterns on the PEO-modified surfaces. Significant reductions in the adsorption of fibrinogen, albumin and lysozyme were observed on both PEO-modified surfaces, although the monofunctional PEO surfaces performed much better in this regard. The reductions in protein adsorption were comparable for all three proteins on both surfaces, suggesting that molecular mass of the protein is not a significant factor in determining the magnitude of protein deposition. Western blot studies showed that the adsorption of proteins from plasma to the monofunctional PEO-modified surfaces was also significantly reduced and surprisingly selective, with very few bands noted relative to the control surfaces and those modified with bifunctional PEO.
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PMID:Surface properties of PEO-silicone composites: reducing protein adsorption. 1588 58

We investigated the ability of certain triblock copolymer surfactant poloxamers of the form polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO-PPO-PEO), to prevent formation of stable aggregates of heat denatured hen egg lysozyme. Differential scanning calorimetry (DSC) and synchrotron small angle x-ray scattering (SAXS) experiments were performed to study the thermodynamics and solution structures of lysozyme at temperatures between 20 and 90 degrees C in the presence and absence of poloxamers with various molecular weights (8.4-14.3 kDa), but similar hydrophile/hydrophobe (PEO:PPO) ratio of 80%. Poloxmer 188 was found to be very effective in preventing aggregation of heat denatured lysozyme and those functioned as a synthetic surfactant, thus enabling them to refold when the conditions become optimal. For comparison, we measured the ability of 8 kDa polyethylene glycol (PEG) to prevent lysozyme aggregation under same conditions. The results of these studies suggest that poloxamers are more efficient than PEG in preventing aggregation of heat denaturated lysozyme. To achieve equivalence, more than an order of magnitude higher concentration of PEG concentration was needed. Apparently, the presence of a hydrophobic segment in the poloxamers increases their ability to target the hydrophobic region of the unfolded proteins and protect them from self association. Given their biocompatibility and the low concentrations at which they effectively facilitate refolding of denatured proteins, they may be useful in the treatment of burns and other conditions resulting in the denaturation of proteins.
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PMID:Surfactant copolymers prevent aggregation of heat denatured lysozyme. 1678 93

A blend mixture of poly(epsilon-caprolactone) (PCL) and poly(ethylene oxide) (PEO) was electrospun to produce fibrous meshes that could release a protein drug in a controlled manner. Various biodegradable polymers, such as poly(l-lactic acid) (PLLA), poly(epsilon-caprolactone) (PCL), and poly(d,l-lactic-co-glycolic acid) (PLGA) were dissolved, along with PEO and lysozyme, in a mixture of chloroform and dimethylsulfoxide (DMSO). The mixture was electrospun to produce lysozyme loaded fibrous meshes. Among the polymers, the PCL/PEO blend meshes showed good morphological stability upon incubation in the buffer solution, resulting in controlled release of lysozyme over an extended period with reduced initial bursts. With varying the PCL/PEO blending ratio, the release rate of lysozyme from the corresponding meshes could be readily modulated. The lysozyme release was facilitated by increasing the amount of PEO, indicating that entrapped lysozyme was mainly released out by controlled dissolution of PEO from the blend meshes. Lysozyme released from the electrospun fibers retained sufficient catalytic activity.
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PMID:Controlled protein release from electrospun biodegradable fiber mesh composed of poly(epsilon-caprolactone) and poly(ethylene oxide). 1732 Oct 84

This paper describes the preparation, characterization, and enzymatic activity of complex coacervate core micelles (C3Ms) composed of poly(acrylic acid) (PAA) and poly(N-methyl-2-vinyl pyridinium iodide)-b-poly(ethylene oxide) (PQ2VP-PEO) to which the antibacterial enzyme lysozyme is end-attached. C3Ms were prepared by polyelectrolyte complex formation between PAA and mixtures containing different ratios of aldehyde and hydroxyl end-functionalized PQ2VP-PEO. This resulted in the formation of C3Ms containing 0-40% (w/w) of the aldehyde end-functionalized PQ2VP-PEO block copolymer (PQ2VP-PEO-CHO). Chemical conjugation of lysozyme was achieved via reductive amination of the aldehyde groups, which are exposed at the surface of the C3M, with the amine groups present in the side chains of the lysine residues of the protein. Dynamic and static light scattering indicated that the conjugation of lysozyme to C3Ms prepared using 10 and 20% (w/w) PQ2VP-PEO-CHO resulted in the formation of unimicellar particles. Multimicellar aggregates, in contrast, were obtained when lysozyme was conjugated to C3Ms prepared using 30 or 40% (w/w) PQ2VP-PEO-CHO. The enzymatic activity of the unimicellar lysozyme-C3M conjugates toward the hydrolysis of the bacterial substrate Micrococcus lysodeikticus was comparable to that of free lysozyme. For the multimicellar particles, in contrast, significantly reduced enzymatic rates of hydrolysis, altered circular dichroism, and red-shifted tryptophan fluorescence spectra were measured. These results are attributed to the occlusion of lysozyme in the interior of the multimicellar conjugates.
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PMID:Complex coacervate core micelles with a lysozyme-modified corona. 1758 20

Surface modification of a segmented polyurethane was achieved by blending with novel PEO-containing amphiphilic triblock copolymers (PEO-polyurethane-PEO). Three copolymers having different PEO MW (550, 2000, 5000) were used as surface modification additives. The protein resistance of the blend surfaces was evaluated using radiolabeling methods. On the blends of copolymers with PEO blocks of MW 2000 and 5000, fibrinogen adsorption from physiologic buffer decreased with increasing copolymer content up to 20 wt%. On the blends with PEO blocks of MW 550, resistance to adsorption for a given copolymer content was much greater. For all three blend types at 20% copolymer content, reductions in adsorption compared to the unmodified PU matrix were greater than 95%. Reductions in adsorption were similar for the 20% blends and surfaces prepared by coating the copolymers directly on the matrix, suggesting that the 20% blend surfaces were completely covered by copolymer. At low copolymer content (< or =10 wt %), fibrinogen adsorption decreased with decreasing PEO block length. This was probably due to increasing surface coverage of the copolymers with decreasing block length. It is therefore concluded that surface density of PEO is more important than PEO MW for the protein resistance of these surfaces. Lysozyme, a much smaller protein, showed adsorption trends similar to fibrinogen. The adsorption of fibrinogen and lysozyme from binary solutions to blends of the copolymer with PEO blocks of 2000 MW was investigated to probe the effects of protein size on adsorption resistance. Fibrinogen and lysozyme showed similar fractional decreases in adsorption relative to the PU matrix independent of the surface density of PEO. However lysozyme was enriched in the surface relative to the solution, that is, it was adsorbed preferentially to fibrinogen.
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PMID:Nonfouling biomaterials based on polyethylene oxide-containing amphiphilic triblock copolymers as surface modifying additives: protein adsorption on PEO-copolymer/polyurethane blends. 1789 76

We describe the stacking and separation of proteins by CE under discontinuous conditions in conjunction with light-emitting diode induced fluorescence (LEDIF) detection using a violet LED at 405 nm. The proteins were derivatized with naphthalene-2,3-dicarboxaldehyde (NDA) to form NDA-protein derivatives prior to CE-LEDIF analysis. During the separation, poly(ethylene oxide) (PEO) solution containing CTAB enters from the cathodic inlet to the capillary via electroosomotic flow (EOF). The optimum conditions are: the capillary was filled with 50 mM glycine buffer (pH 9.0) containing 1.0 mM CTAB, NDA-protein derivatives were prepared in deionized water containing 1.0 mM CTAB, and 0.6% PEO was prepared in 50 mM glycine (pH 9.0) containing 2.0 mM CTAB. The analysis of four NDA-protein derivatives is fast (<3 min), with RSD <1.5% in terms of migration time. In order to improve the sensitivity of NDA-protein derivatives, a stacking approach based on increases in viscosity and electric field, as well as sieving was applied. The efficient stacking approach provides LODs (S/N = 3) of 2.41, 0.59, 0.61, and 4.22 nM for trypsin inhibitor, HSA, beta-lactoglobulin, and lysozyme, respectively. In addition, we also applied the stacking approach to determination of the concentration of HSA in one urine sample, which was determined to be 0.31 +/- 0.05 microM (n = 3).
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PMID:Stacking and separation of protein derivatives of naphthalene-2,3-dicarboxaldehyde by CE with light-emitting diode induced fluorescence detection. 1806 34

Protein adsorption on poly(ethylene oxide) (PEO) and oligo(ethylene oxide) (OEO) monolayers is studied at different packing densities using the Langmuir technique. In the case of a PEO monolayer, a protein adsorption minimum is revealed at sigma(-1) = 10 nm(2) for both lysozyme and fibrinogen. Manifested are two packing density regimes of steric repulsion and compressive attraction between PEO and a protein on top of the overall attraction of the protein to the air/water interface. The observed protein adsorption minimum coincides with the maximum of the surface segment density at sigma(-1) = 10 nm(2). However, OEO monolayer presents a different scenario, namely that the amount of protein adsorbed decreases monotonically with increasing packing density, indicating that the OEO chains merely act as a steric barrier to protein adsorption onto the air/water interface. Besides, in the adsorption of fibrinogen, three distinct kinetic regimes controlled by diffusion, penetration and rearrangement are recognized, whereas only the latter two were made out in the adsorption of lysozyme.
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PMID:Protein resistance of (ethylene oxide)n monolayers at the air/water interface: effects of packing density and chain length. 1816 82

The interaction of the proteins bovine serum albumin (BSA), lysozyme (Lys), lactoferrin (Lf), and fibronectin (Fn) with surfaces of protein-resistant poly(ethylene oxide) (PEO) and protein-adsorbing poly(acrylic acid) (PAA) fabricated by plasma-enhanced chemical vapor deposition has been studied with quartz crystal microbalance with dissipation monitoring (QCM-D). We focus on several parameters which are crucial for protein adsorption, i.e., the isoelectric point (pI) of the proteins, the pH of the solution, and the charge density of the sorbent surfaces, with the zeta-potential as a measure for the latter. The measurements reveal adsorption stages characterized by different segments in the plots of the dissipation vs frequency change. PEO remains protein-repellent for BSA, Lys, and Lf at pH 4-8.5, while weak adsorption of Fn was observed. On PAA, different stages of protein adsorption processes could be distinguished under most experimental conditions. BSA, Lys, Lf, and Fn generally exhibit a rapid initial adsorption phase on PAA, often followed by slower processes. The evaluation of the adsorption kinetics also reveals different adsorption stages, whereas the number of these stages does not always correspond to the structurally different phases as revealed by the D- f plots. The results presented here, together with information obtained in previous studies by other groups on the properties of these proteins and their interaction with surfaces, allow us to develop an adsorption scenario for each of these proteins, which takes into account electrostatic protein-surface and protein-protein interaction, but also the pH-dependent properties of the proteins, such as shape and exposure of specific domains.
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PMID:pH-dependent immobilization of proteins on surfaces functionalized by plasma-enhanced chemical vapor deposition of poly(acrylic acid)- and poly(ethylene oxide)-like films. 1854 95


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