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)

The surface reactions of poly(2-hydroxyethylmethacrylate) (PHEMA) and the copolymer poly(HEMA-methacrylic acid) (PHEMA/MAA) with methyltrimethoxysilane, ethyltrimethoxysilane and phenyltrimethoxysilane have been characterized by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. A model compound, hydroxyethyl isobutyrate was synthesized and subsequently reacted with phenyltrimethoxysilane. Its FTIR spectrum was compared with the ATR-FTIR spectra mentioned above. Protein adsorption experiments showed that silanized PHEMA/MAA soft contact lenses adsorbed less lysozyme than the untreated lenses.
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PMID:Surface modification of soft contact lenses: silanization, wettability and lysozyme adsorption studies. 374 58

Lysozyme was adsorbed on spin cast and lathe cut soft contact lenses of poly-2-hydroxyethylmethacrylate (PHEMA) and on poly-HEMA-methacrylic acid (PHEMA/MAA). The in vitro adsorption process was followed by ATR-FTIR. Lysozyme adsorbs both, reversibly and irreversibly, on the surfaces. While the reversible bound lysozyme experiences only minor changes in its secondary structure, conformational changes occur for the irreversibly adsorbed protein. The type and extent of structural changes depend on the degree of protein coverage on the lens surface, as well as the chemical structure and surface morphology of the lenses. PHEMA/MAA lenses adsorbed thirty times more lysozyme than either of the PHEMA lenses. Fabrication processes appear to induce different adsorption behaviour, PHEMA lathe cut lenses adsorb twice the amount of protein compared with PHEMA spin cast lenses.
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PMID:Protein adsorption on hydrogels. II. Reversible and irreversible interactions between lysozyme and soft contact lens surfaces. 405 47

A two-phase sequential dynamic change in the secondary structure of hen egg lysozyme (Lys) adsorbed on solid substrates was observed. The first phase involved fast conversion of alpha-helix to random/turns (within the first minute or at very low coverage or high substrate wettability) with no perceptible change in beta-sheet content. The second phase (1-1200 min), however, involved a relatively slow conversion from alpha-helix to beta-sheet without a noticeable change in random/turns. An important finding of this work is that the concentration of lysozyme in the adsorbed state has a substantial effect on the fractional content of secondary structures. Attenuated total reflection Fourier transform infrared (ATR/FTIR) spectroscopy, along with a newly-developed optimization algorithm for predicting the content of secondary structure motifs, was used to correlate the secondary structure and the amount of adsorbed lysozyme with the surface wettability of six different flat nanoporous substrates. Although three independent variables, surface wettability, solution concentration and time for adsorption, were used to follow the fractional structural changes of lysozyme, the results were all normalized onto a single plot with the amount adsorbed as the universal independent variable. Consequently, lateral interactions among proteins likely drive the transition process. Direct intermolecular force adhesion measurements between lysozyme and different functionalized self-assembled alkanethiol monolayers confirm that hydrophobic surfaces interact strongly with proteins. The lysozyme-unfolding pathway during early adsorption appears to be similar to that predicted by published molecular modeling results.
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PMID:Protein unfolding at interfaces: slow dynamics of alpha-helix to beta-sheet transition. 1528 Nov 20

We have demonstrated that globular proteins, such as hen egg lysozyme in phosphate buffered saline at room temperature, lose native structural stability and activity when adsorbed onto well-defined homogeneous solid surfaces. This structural loss is evident by alpha-helix to turns/random during the first 30 min and followed by a slow alpha-helix to beta-sheet transition. Increase in intramolecular and intermolecular beta-sheet content suggests conformational rearrangement and aggregation between different protein molecules, respectively. Amide I band attenuated total reflection/Fourier transformed infrared (ATR/FTIR) spectroscopy was used to quantify the secondary structure content of lysozyme adsorbed on six different self-assembled alkanethiol monolayer surfaces with -CH3, -OPh, -CF3, -CN, -OCH3, and -OH exposed functional end groups. Activity measurements of adsorbed lysozyme were in good agreement with the structural perturbations. Both surface chemistry (type of functional groups, wettability) and adsorbate concentration (i.e., lateral interactions) are responsible for the observed structural changes during adsorption. A kinetic model is proposed to describe secondary structural changes that occur in two dynamic phases. The results presented in this article demonstrate the utility of the ATR/FTIR spectroscopic technique for in situ characterization of protein secondary structures during adsorption on flat surfaces.
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PMID:Protein structural perturbation and aggregation on homogeneous surfaces. 1554 59

Thin films obtained from a layer-by-layer deposition of a weak polycarboxylic acid and a positively charged globular protein were studied by in situ ATR-FTIR. The system was chicken egg lysozyme (Lys), bovine pancrease ribonuclease A (RNase), or bovine gamma-globulin (IgG) self-assembled with polycarboxylic acids. When the pH value was lowered below a critical point, the growth of films and their tolerance to decomposition by added sodium chloride improved dramatically. Stabilization of protein/polyacid films in salt solutions at lower pH values occurred due to the onset of nonelectrostatic interactions to intermolecular binding within protein/polyacid multilayers and was controlled by polyacid ionization within the film rather than the pH of the external solution. A fractional ionization of polyacid in the pH-stabilization region was lower with protein-containing films than for polyacid/linear polycation films, reflecting hindrance of the inter-association of protonated carboxylic groups by protein globules. Practical ramifications of the pH-stabilization effect might extend to areas of biotechnology and biomaterials.
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PMID:Multilayers of a globular protein and a weak polyacid: role of polyacid ionization in growth and decomposition in salt solutions. 1587 5

Poly(epsilon-caprolactone) (PCL)/chitin and PCL/chitosan blend films with compositional gradients were successfully fabricated by a dissolution/diffusion method; that is, repeatedly pouring the PCL/chitin (or PCL/chitosan) blend solutions, with variable composition, onto polysaccharide layers. The compositional gradient structure in the resulting films was characterized by polarized optic microscopy, ATR-FT-IR and trans-FT-IR microscopic spectroscopy. Enzymatic degradability of the PCL/chitin and PCL/chitosan blend films with compositional gradients in the presence of lysozyme was compared with those of homogeneous films and two-layer films. It was found that the degradation rate of PCL/chitin blend films with a compositional gradient was far lower than that of the neat chitin film, whereas the degradation rate of PCL/chitosan blend films with a compositional gradient was close to that of the neat chitosan film. The suppression of the chitosan crystallization, which accelerates the enzymatic degradation, at the surface of PCL/chitosan films with a compositional gradient was much more severe than that for PCL/chitin films with a compositional gradient.
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PMID:Poly(epsilon-caprolactone)/chitin and poly(epsilon-caprolactone)/chitosan blend films with compositional gradients: fabrication and their biodegradability. 1653 61

Protein adsorption during hydrophobic interaction chromatography (HIC) may induce conformational changes. We analyzed conformational changes in three model proteins, bovine serum albumin (BSA), beta-lactoglobulin, and lysozyme by attenuated total reflectance Fourier transform infrared (ATR FT-IR) spectroscopy and pulse response experiments. Conformational changes occurred in the secondary structure of BSA, the tertiary structure of beta-lactoglobulin, and no changes occurred in lysozyme under the adsorption conditions investigated. Protein unfolding varied substantially among proteins, caused incomplete isocratic elution in HIC, and was confirmed by in situ assessments. Lower temperatures and binding capacities significantly reduced protein unfolding; the activation energy for unfolding ranged from 47 to 125 kJ/mol.
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PMID:Hydrophobic interaction chromatography of proteins V. Quantitative assessment of conformational changes. 1854 Dec 49

Applying ATR-FTIR (attenuated total reflection Fourier transform infrared) and TIRF (total internal reflection fluorescence) spectroscopy, we have studied the secondary structure and aggregation properties of different proteins which are adsorbed at a poly(acrylic acid) (PAA) brush that covers a macroscopically large, planar surface. The PAA brush has been prepared on the surface of an ATR silicon crystal or a quartz plate. The preparation includes the deposition of a thin poly(styrene) film by spin-coating and the transfer of the diblock copolymer poly(styrene)-poly(acrylic acid) onto the hydrophobic film using the Langmuir-Schafer technique. It has been found that the proteins hen egg white lysozyme, bovine serum albumin, bovine alpha-lactalbumin, and bovine insulin adsorb spontaneously at a PAA brush at neutral pD values, albeit to different degrees. The secondary structure of the proteins was estimated from a decomposition of the amide I'-band in the observed ATR-FTIR spectra. Generally, the fractions of secondary structure elements recovered in this way were almost identical to those found when the proteins are native in solution. In addition, the tendency of insulin to form amyloid fibrils has also been tested when the protein is adsorbed at a planar PAA brush. Insulin is known to form amyloid fibrils in solution at low pH values and elevated temperatures. The experiments performed in this study suggest that a PAA brush does not promote fibril formation of insulin. Rather, insulin that is adsorbed at a PAA brush seems to be excluded from fibril formation pathways even at pD = 2 and 60 degrees C, where fibril formation of insulin is triggered in solution. Overall, the results of this study demonstrate that a planar PAA brush may serve as a mild environment for immobilized proteins.
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PMID:Native-like structure of proteins at a planar poly(acrylic acid) brush. 1909 23

A model protein (lysozyme) was incorporated into monoolein-based reverse hexagonal (H(II)) mesophase and its structure effects were characterized by small angle X-ray scattering, ATR-FTIR spectroscopy, and rheological measurements. Modifications in molecular organization of the H(II) mesophases as well as the conformational stability of lysozyme (LSZ) as a function of pH and denaturating agent (urea) were clarified. Up to 3 wt.% LSZ can be solubilized into the H(II). The vibration FTIR analysis revealed that LSZ interacted with OH groups of glycerol monooleate (GMO) in the outer interface region, resulting in strong hydrogen bonding between the surfactant and its environment. Simultaneously, the decrease in the hydrogen-bonded carbonyl population of GMO was monitored, indicating dehydration of the monoolein carbonyls. These molecular interactions yielded a minor decrease in the lattice parameter of the systems, as detected by small angle X-ray scattering. Furthermore, LSZ was crystallized within the medium of the hexagonal structures in a single crystal form. The alpha-helix conformation of lysozyme was stabilized at high pH conditions, demonstrating greater helical structure content, compared to D(2)O solution. Moreover, the hexagonal phase decreased the unfavorable alpha-->beta transition in lysozyme, thereby increasing the stability of the protein under chemical denaturation. The rheological behavior of the hexagonal structures varied with the incorporation of LSZ, reflected in stronger elastic properties and pronounced solid-like response of the systems. The hydrogen bonding enhancement in the interface region of the structures was most likely responsible for these phenomena. The results of this study provided valuable information on the use of hexagonal systems as a carrier for incorporation and stabilization of proteins for various applications.
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PMID:Lysozyme entrapped within reverse hexagonal mesophases: physical properties and structural behavior. 1974 40

The influence of urea and trimethylamine-N-oxide (TMAO) on the structure of water and secondary structure of hen egg white lysozyme (HEWL) has been investigated. The hydration of these osmolytes was studied in aqueous solutions by means of FTIR spectra of HDO isotopically diluted in H(2)O. The difference spectra procedure was applied to remove the contribution of bulk water and thus to separate the spectra of solute-affected HDO. The structural-energetic characteristic of these solute-affected water molecules shows that, on average, water affected by TMAO forms stronger H-bonds and is more ordered than pure water. In the case of urea, the H-bonds are very similar to those in pure water. To facilitate the interpretation of the obtained spectral results, calorimetric measurements, DFT calculations, and molecular dynamics (MD) simulations of aqueous osmolyte clusters were performed. All of these results confirmed that the interactions of TMAO with water molecules are much stronger than those of urea with water. Additional ATR FTIR measurements were performed to characterize the influence of the examined osmolytes on the secondary structure of HEW lysozyme. The type of interactions (direct or indirect) was determined, based on the second derivatives of ATR protein spectra record during an increase in the osmolyte concentration. The changes in the amide I band shape caused by urea or TMAO were found to correlate quite well with changes in the water structure around these osmolytes.
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PMID:Effects of urea and trimethylamine-N-oxide on the properties of water and the secondary structure of hen egg white lysozyme. 1981 39


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