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)

Longitudinal sound velocity of tetragonal hen-egg-white (HEW) lysozyme crystals was measured during air drying by ultrasonic pulseecho method. The sound velocity increases with exposure to open air and approaches a constant value. The maximum value is approximately 2900 m/s that is about 1.6 times as much as that of original one before drying. In addition, the sound velocity clearly recovers to original one after immersing the dried crystal in solution. Therefore, the sound velocity in tetragonal HEW lysozyme crystals can be reversibly changed due to dehydration and rehydration. These changes in sound velocity are discussed in the light of water-mediated intramolecular and intermolecular interactions in the crystals.
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PMID:Effect of intracrystalline water on longitudinal sound velocity in tetragonal hen-egg-white lysozyme crystals. 1524 61

Organic solvents are known to bring about dehydration of proteins, the molecular basis of which has remained uncharacterized. The dehydration effect in many cases leads to eventual unfolding of proteins through the macroscopic solvent effect. In some cases, the organic solvent molecules also bind to protein surfaces, thereby forcing local unfolding. The X-ray structure of hen egg-white lysozyme co-crystallized in the presence of alcohols with varying hydrophobicities has been studied. It was noticed that although the alcohols have very little effect on the conformation of the overall protein structure, they profoundly affect protein hydration and disorder of the bound waters. Systematic analysis of the water structure around the lysozyme molecule suggests that an increasing order of hydrophobicity of alcohols is directly proportional to the higher number of weakly bound waters in the protein. As anticipated, the water molecules in the native structure with high temperature factors (>/=40 A(2)) attain higher disorder in the presence of alcohols. It is believed that the disorder induced in the water molecules is a direct consequence of alcohol binding.
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PMID:Effect of alcohols on protein hydration: crystallographic analysis of hen egg-white lysozyme in the presence of alcohols. 1598 24

The angle dependencies of diffuse x-ray scattering intensities were studied in a wide range of angles from 3 to 80 degrees for water-soluble and membrane proteins with a different structural organization: alpha-helical protein myoglobin, alpha-helical protein serum albumen, alpha + beta protein lysozyme, and transmembrane proteins of photosynthetic reaction centers (RC) from purple bacteria Rhodobacter sphaeroides, and Blastochlorii (Rhodopseudomonas) viridis containing cytocrome c, situated out side the membrane, and for H and L+M subunits of membrane protein of reaction center from Rb. sphaeroides for various hydration degrees. The hydration/dehydration process was studied for water-soluble proteins (within hydration range from h = 0.05 to h = 1). The hydration/dehydration process appears to be reversible. All water-soluble proteins show a 10 angstroms peak, and proteins of reaction center do not show this peak. A quantitative comparable study of the behaviour for of the 10 angstroms peak different proteins the degree of lysozyme hydration increases from h = 0.05 to h = 0.45, the protein structure slightly changes (most probably the motifoffolding), the structure of myoglobin in solution is slightly different from the structure in crystal. By taking into account the changes in the shape and intensity of the 10 angstroms peak only, it is impossible to make the conclusion about structural changes in other proteins studied. A correlation between the structural changes observed and dynamic and functional properties of proteins is discussed.
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PMID:[A study of protein structure changes during hydration by diffuse X-ray scattering. I. The intensity and the shape of "10-angstrom" maximum]. 1635 78

Near-infrared spectroscopy (NIR) of various proteins (bovine serum albumin, lysozyme, ovalbumin, gamma-globulin, beta-lactoglobulin, myoglobin, cytochrome-c) was investigated as a possible analytical method of the protein secondary structure in various physical states. The spectra of proteins in aqueous solutions (transmission mode, solvent-compensated) and those in freeze-dried solids (nondestructive diffuse reflection mode) showed several bands at similar frequencies in the combination (4000-5000 cm(-1)) and first overtone (5600-6600 cm(-1)) spectral regions. The normalized second-derivative near-infrared spectra of proteins in aqueous solutions suggested that some bands indicated alpha-helix (4090, 4365-4370, 4615, and 5755 cm(-1)) and beta-sheet (4060, 4405, 4525-4540, 4865, and 5915-5925 cm(-1)) structures. The proteins mostly maintained spectra characteristic of their native structure after freeze-drying, although some reductions in alpha-helical structure and increase in unordered or beta-sheet structures were observed. The near-infrared analysis also showed beta-sheet formation of heat-treated BSA in aqueous solutions and in subsequently freeze-dried solids. The present results thus indicated that the nondestructive near-infrared analysis can be used for the investigation of dehydration-induced changes in protein secondary structures.
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PMID:Near-infrared analysis of protein secondary structure in aqueous solutions and freeze-dried solids. 1649 74

Two monoclinic crystals (space group P2(1)) of hen egg-white lysozyme, a type I crystal grown at room temperature in a D2O solution with pD 4.5 containing 2%(w/v) sodium nitrate and a type II crystal grown at 313 K in a 10%(w/v) sodium chloride solution with pH 7.6, were each transformed into another monoclinic crystal with the same space group by dehydration-induced phase transition. Changes in X-ray diffraction were recorded to monitor the progress of the crystal transformation, which started with the appearance of diffuse streaks. In both crystals, the intensity of h + l odd reflections gradually weakened and finally disappeared on completion of the transformation. X-ray diffraction in the intermediate state indicated the presence of lattices of both the native and transformed crystals. In the native type I crystal, two alternate conformations were observed in the main chain of the region Gly71-Asn74. One conformer bound a sodium ion which was replaced with a water molecule in the other conformer. In the transformed crystal, the sodium ion was removed and the main-chain conformation of this region was converted to that of the water-bound form. The transformed crystal diffracted to a higher resolution than the native crystal, while the peak width of the diffraction spots increased. Analysis of the thermal motion of protein molecules using the TLS model has shown that the enhancement of the diffraction power in the transformed crystal is mainly ascribable to the suppression of rigid-body motion owing to an increase in intermolecular contacts as a result of the loss of bulk solvent.
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PMID:Structural phase transition of monoclinic crystals of hen egg-white lysozyme. 1655 38

A controlled-release device that responds to a specific molecular signal is an ideal goal in drug delivery and tissue engineering. A molecular recognition ion gating membrane, in which a copolymer of N-isopropylacrylamide and benzo[18]-crown-6-acrylamide was grafted onto the surface of the porous polyethylene film, was used to control the permeability of vitamin B12 and lysozyme in response to a specific ion signal. The observed response depended on the amount of grafted copolymer. When the grafting ratio was below 15%, the membrane pores opened by Ca2+ and closed by Ba2+. The permeability of model drugs became higher by opening of the pores. On the other hand, when the grafting ratio was above 15%, the properties of the membrane changed. The permeability of model drugs became lower by Ca2+ due to dehydration of the grafted copolymer. The opposite responses were observed at different grafting ratios.
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PMID:Controlled release of model drugs through a molecular recognition ion gating membrane in response to a specific ion signal. 1658 80

We have studied hydration (and dehydration) of thermally denatured hen egg lysozyme using sorption calorimetry. Two different procedures of thermal denaturation of lysozyme were used. In the first procedure the protein was denatured in an aqueous solution at 90 degrees C, in the other procedure a sample that contained 20% of water was denatured at 150 degrees C. The protein denatured at 90 degrees C showed very similar sorption behavior to that of the native protein. The lysozyme samples denatured at 150 degrees C were studied at several temperatures in the range of 25-60 degrees C. In the beginning of sorption, the sorption isotherms of native and denatured lysozyme are almost identical. At higher water contents, however, the denatured lysozyme can absorb a greater amount of water than the native protein due to the larger number of available sorption sites. Desorption experiments did not reveal a pronounced hysteresis in the sorption isotherm of denatured lysozyme (such hysteresis is typical for native lysozyme). Despite the unfolded structure, the denatured lysozyme binds less water than does the native lysozyme in the desorption experiments at water contents up to 34 wt %. Glass transitions in the denatured lysozyme were observed using both differential scanning calorimetry and sorption calorimetry. Partial molar enthalpy of mixing of water in the glassy state is strongly exothermic, which gives rise to a positive temperature dependence of the water activity. The changes of the free energy of the protein induced by the hydration stabilize the denatured form of lysozyme with respect to the native form.
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PMID:Hydration of thermally denatured lysozyme studied by sorption calorimetry and differential scanning calorimetry. 1670 76

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

A monoclinic lysozyme crystal grown in NaCl solution was transformed into a new monoclinic crystal form by controlled dehydration. This crystal-to-crystal phase transition was accompanied by 20-40% solvent loss and the transformed crystal diffracted to prominently high resolution. The structures of the native and transformed crystals were determined at 1.4 and 1.15 A resolution, respectively. In the native crystal a sodium ion was bound to the loop region Ser60-Asn74; however, it was released in the transformed crystal and a water molecule occupied this position. In the transformed crystal a sodium ion was bound to the carboxyl group of Asp52, a catalytic residue. The same structural change was observed in the phase transition of a crystal soaked in a saturated NaCl solution. In contrast, a crystal soaked in 10% NaCl solution was transformed in a shorter time with a smaller loss of solvent and the structure of the sodium-binding site was conserved in the transformed crystal. The high concentration of NaCl is likely to stabilize the crystal structure against dehydration by forming salt linkages between protein molecules. This suggests that the sodium ion in the crystal regulates not only the structural change of the loop region Ser60-Asn74 but also the molecular rearrangement caused by dehydration.
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PMID:Effect of a sodium ion on the dehydration-induced phase transition of monoclinic lysozyme crystals. 1770 71

The inherent instability of proteins when isolated from their native conditions creates the necessity of suitable stabilisation techniques. Because of the instability of proteins in solution it is often necessary to produce them as solid formulations. A method of producing relatively stable, solid protein pharmaceuticals is to incorporate them with a suitable excipient into an amorphous matrix by dehydration. The use of spray dried multiple excipient/single protein blends was compared to single excipient/protein systems using lysozyme as a model protein to establish the stabilising ability of such systems. Unprocessed controls and spray dried samples were characterised structurally by X-ray powder diffraction and Fourier transform Raman spectroscopy and also thermally by differential scanning calorimetry and thermogravimetric analysis. Retained lysozyme activity was assayed enzymatically. To assess long-term stability, samples were subjected to conditions of elevated temperature and relative humidity (RH) 40 degrees C/75% RH. Structural and thermal analysis of samples revealed that mannitol/trehalose spray dried excipient/lysozyme blends were completely amorphous upon production but partially recrystallised upon storage at elevated temperature and RH. Biological activity assays revealed that samples containing trehalose retained the highest percentage activity. Under the conditions employed mannitol/trehalose systems stabilise lysozyme more effectively than single excipient systems due to their ability to form amorphous products.
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PMID:Do co-spray dried excipients offer better lysozyme stabilisation than single excipients? 1826 76


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