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

---

Query: EC:3.2.1.17 (lysozyme)
21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Covalent grafting of poly(ethylene glycol) (PEG) to pharmaceutical proteins, "PEGylation", is becoming more commonplace due to improved therapeutic efficacy. As these conjugates encounter interfaces in manufacture, purification, and end use and adsorption to these interfaces may alter achievable production yields and in vivo efficacies, it is important to understand how PEGylation affects protein adsorption mechanisms. To this end, we have studied the adsorption of unmodified and PEGylated chicken egg lysozyme to silica, using optical reflectometry, total internal reflection fluorescence (TIRF) spectroscopy, and atomic force microscopy (AFM) under varying conditions of ionic strength and extent of PEG modification. PEGylation of lysozyme changes the shape of the adsorption isotherm and alters the preferred orientation of lysozyme on the surface. There is an abrupt transition in the isotherm from low to high surface excess concentrations that correlates with a change in orientation of mono-PEGylated conjugates lying with the long axis parallel to the silica surface to an orientation with the long axis oriented perpendicular to the surface. No sharp transition is observed in the adsorption isotherm for di-PEGylated lysozyme within the range of concentrations examined. The net effect of PEGylation is to decrease the number of protein molecules per unit area relative to the adsorption of unmodified lysozyme, even under conditions where the surface is densely packed with conjugates. This is due to the area sterically excluded by the PEG grafts. The other major effect of PEGylation is to make conjugate adsorption significantly less irreversible than unmodified lysozyme adsorption.
...
PMID:Adsorption of poly(ethylene glycol)-modified lysozyme to silica. 1569 78

Grafting of poly(ethylene glycol) (PEG) is a common strategy for reducing nonspecific interactions of surfaces with proteins. We have used grafting at "cloud point" solution conditions that ensures maximum grafting density of linear methoxy terminated PEG-aldehyde (mPEG-ald, M(w) = 5000 and 30000). In an alternative approach, surfaces were modified with layers prepared from isocyanate terminated, star shaped poly(ethylene glycol-stat-propylene glycol) prepolymers (80% ethylene glycol, six arms, M(w) = 3000, 12,000, and 18,000; this compound will be referred to as "Star PEG" in the text). Due to the highly reactive endgroups, these molecules form a dense network on the substrate with a high polymer surface coverage. The two systems were compared regarding their ability to prevent unspecific adsorption of insulin and lysozyme. The layers were analyzed by ellipsometry, contact angle measurements, and XPS. Protein adsorption was monitored by surface MALDI-TOF MS and fluorescence microscopy. No protein adsorption could be detected on Star PEG coatings and on mPEG-ald 5000, whereas mPEG-ald 30,000 could only prevent adsorption of lysozyme but not of the smaller insulin.
...
PMID:Comparison of coatings from reactive star shaped PEG-stat-PPG prepolymers and grafted linear PEG for biological and medical applications. 1576 65

To improve the stability of lysozyme-incorporated polyion complex (PIC) micelles in physiological condition, three types of hydrophobic groups, including phenyl (Phe), naphthyl (Nap), and pyrenyl (Py) terminal groups, were separately introduced to the omega-end of poly(ethylene glycol)-poly(alpha,beta-aspartic acid) block copolymers (PEG-P(Asp)). The goal was to enhance association forces between the enzyme, lysozyme, and PEG-P(Asp) carriers. Introduction of these hydrophobic groups significantly decreases micellar critical association concentration and increases the micellar tolerability against increasing NaCl concentrations. Particularly, PIC micelles formed from PEG-P(Asp) with Py groups was most stable against increasing NaCl concentrations up to 0.1 M. Significant deviation from a spherical shape for the micelles was also observed for the PEG-P(Asp)-Py system, consistent with an increased association number.
...
PMID:Stabilization of lysozyme-incorporated polyion complex micelles by the omega-end derivatization of poly(ethylene glycol)-poly(alpha,beta-aspartic acid) block copolymers with hydrophobic groups. 1577 33

In this paper, we compared the efficiency of polymer films, made of a poly(ethylene glycol) (PEG2,000)/poly(d,l-lactide) (PLA50) mixture, or a PEG2,000-PLA50 copolymer, to prevent adsorption of a model protein, the hen egg-white lysozyme (HEWL), at the air-water interface. This was achieved by analyzing the surface pressure/surface area curves, and the X-ray reflectivity data of the polymer films spread on a Langmuir trough, obtained in absence or in presence of the protein. For both the mixture and the copolymer, the amount of protein adsorbed at the air-water interface decreases when the density of the polymer surface coverage increases. It was shown that even in a condensed state, the polymer film made by the mixture can not totally prevent HEWL molecules to adsorb and penetrate the polymer mixed film, but however, protein molecules would not be directly exposed to the more hydrophobic phase, i.e. the air phase. It was also shown that the configuration adopted by the copolymer at the interface in its condensed state would prevent adsorption of HEWL molecules for several hours; this would be due in particular to the presence of PEG segments in the interfacial film.
...
PMID:Interactions between hen egg-white lysozyme, PEG2,000, and PLA50 at the air-water interface. 1583 60

High-speed counte-recurrent chromatography (HSCCC) is a continuous liquid-liquid partition chromatography without solid matrix, which has the significant features of high resolution and high recovery. The separation of bio-macromolecule in aqueous two-phase systems (ATPs) with HSCCC is still under research, and the establishment of high-speed counter-current aqueous two-phase chromatography (HSCCC-ATP) relies on the improvement of equipment structure and optimization of operation parameters. By using a multi-column high-speed counter-current chromatograph, the separation of protein mixture and the purification of ovalbumin from hen egg white were studied. The effects of pH and PEG concentration on the partition coefficients of proteins were tested in PEG1000-phosphate ATPs, and distinct differences among partition coefficients of proteins were found at pH 9.2 and 15.0% (W/W) PEG concentration in said system. The separation of protein mixture, consisting of cytochrome C, lysozyme and myoglobin was successfully performed in 15.0% (W/W) PEG1000-17.0% (W/W) potassium phosphate ATPs at pH 9.2 with high-speed counter-current chromatograph at rotation speed of 850r/min and flow rate of 0.8mL/min, using upper phase as stationary phase. pH and PEG concentration also had distinct effects on the partition coefficients of the major protein components in hen egg white, including ovaltransferrin, ovalbumin and lysozyme. The optimal pH value and PEG concentration for the purification of ovalbumin by HSCCC-ATP were found to be 9.2 and 16.0% (W/W) respectively. Ovalbumin was successfully purified to homogeneity from the hen egg white sample in 16.0% (W/W) PEG1000-17.0% (W/W) potassium phosphate ATPs at pH 9.2 with high-speed counter-current chromatograph at rotation speed of 850r/min and flow rate of 1.8mL/min, using upper phase as stationary phase. The purification recovery of ovalbumin was around 95%.
...
PMID:[Purification of ovalbumin from hen egg white by high-speed counter-current aqueous two-phase chromatography]. 1585 42

A one-step, mild procedure based on coaxial electrospinning was developed for incorporation and controlled release of two model proteins, BSA and lysozyme, from biodegradable core-shell nanofibers with PCL as shell and protein-containing PEG as core. The thickness of the core and shell could be adjusted by the feed rate of the inner dope, which in turn affected the release profiles of the incorporated proteins. It was revealed that the released lysozyme maintained its structure and bioactivity. The current method may find wide applications for controlled release of proteins and tissue engineering.
...
PMID:A facile technique to prepare biodegradable coaxial electrospun nanofibers for controlled release of bioactive agents. 1615 37

The partitioning of model proteins (bovine serum albumin, ovalbumin, trypsin and lysozyme) was assayed in aqueous two-phase systems formed by a salt (potassium phosphate, sodium sulfate and ammonium sulfate) and a mixture of two polyethyleneglycols of different molecular mass. The ratio between the PEG masses in the mixtures was changed in order to obtain different polymer average molecular mass. The effect of polymer molecular mass and polydispersivity on the protein partition coefficient was studied. The relationship between the logarithm of the protein partition coefficient and the average molecular mass of the phase-forming polymer was found to depend on the polyethyleneglycol molecular mass, the salt type in the bottom phase and the molecular weight of the partitioned protein. The polymer polydispersivity proved to be a very useful tool to increase the separation between two proteins having similar isoelectrical point.
...
PMID:Polyethyleneglycol molecular mass and polydispersivity effect on protein partitioning in aqueous two-phase systems. 1632 79

The utility of PEGylation for improving therapeutic protein pharmacology would be substantially expanded if the authentic protein drugs could be regenerated in vivo. Diminution of kinetic constants of both enzymes and protein ligands are commonly encountered following permanent bioconjugation with poly(ethylene glycol) polymers. In further development of releasable linker technology, we investigated an amino PEG anchimeric prodrug system, based on either the linear or branched bicin3 (BCN3) linkage, one promising representative of several aliphatic ester structures synthesized from N-modifed bis-2-hydroxyethylglycinamide (bicin). Protein models included an enzyme, lysozyme, and a receptor ligand, interferon-beta-1b, for preparation of linear or branched mono- and multi-PEGylated conjugates as inactive PEG-BCN3 prodrugs. The kinetics of protein release, both in plasma (in vitro) and in mice (in vivo), correlated with the number of PEG attachments, and the plasma half-lives of PEG release spanned a duration of hours to days within the therapeutically relevant window. Capillary electrophoresis, SDS-PAGE, mass determination, and enzymatic and antiviral activity determinations demonstrated regeneration of equivalent native proteins from the inactive PEG-BCN3 conjugates. Pharmacokinetic analysis of the PEGylated interferon-beta-1b administered subcutaneously in mice demonstrated an over 20-fold expansion of the area under the curve exposure of bioactive protein when compared to native protein.
...
PMID:Linear and branched bicin linkers for releasable PEGylation of macromolecules: controlled release in vivo and in vitro from mono- and multi-PEGylated proteins. 1653 64

An efficient method for obtaining DNA from compost which contained high levels of organic matter was developed. The protocol consisted of washing with phosphate-EDTA before extraction, cell lysis with hot-SDS and enzymes (lysozyme, lywalzyme, proteinase K), removing humic acid and other inhibitors with PVPP and precipitation with PEG-8000. The compost total DNA was extracted from four different composts, the DNA yield was 63.54 +/- 12.08 to approximately 106.50 +/- 28.36 microg/g of dry compost. Molecular size of DNA obtained using this protocol was about 23kb and contained low protein and humic acid contamination with the A260/A280 ratios exceeding 1.6 and A260/A230 ratios reaching 1.8. Usually, additional purification steps such as agarose gel electrophoresis, gel permeation chromatography, or affinity chromatography were needed to get PCR-amplifiable DNA, but the DNA obtained using this protocol could directly be used to PCR-amplification and restriction enzyme digestion. Just like purity of DNA template, lower DNA yield also appears to introduce a bias towards lower community diversity. In this study compared the purified DNA the direct DNA reveals higher microbial community diversity assessed by denaturing gradient gel electrophoresis(DGGE) of amplified V3 region of 16S rDNA.
...
PMID:[An efficient method for DNA extraction from compost]. 1657 88

Measurements of liquid-liquid phase transition temperatures (cloud points) of mixtures of a protein (lysozyme) and a polymer, poly(ethylene glycol) (PEG) show that the addition of low molecular weight PEG stabilizes the mixture whereas high molecular weight PEG was destabilizing. We demonstrate that this behavior is inconsistent with an entropic lysozyme-PEG depletion interaction and suggest that an energetic lysozyme-PEG attraction is responsible. In order to independently characterize the lysozyme-PEG interactions, light scattering experiments on the same mixtures were performed to measure second and third virial coefficients. These measurements indicate that PEG induces repulsion between lysozyme molecules, contrary to the depletion prediction. Furthermore, it is shown that third virial terms must be included in the mixture's free energy in order to qualitatively capture our data.
...
PMID:Light scattering and phase behavior of lysozyme-poly(ethylene glycol) mixtures. 1660 27


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---