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

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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)

Differential scanning calorimetric (DSC) measurements were performed on the thermal denaturation of lysozyme and lysozyme complexed with N-acetyl-D-glucosamine (GlcNAc) at pH 5.00 (acetate buffer), 4.25 and 2.25 (Gly-HCl buffer). DSC data have been analyzed to obtain denaturation temperature T(d), enthalpy of denaturation DeltaH(D), heat capacity of denaturation DeltaC(pd) and cooperativity index eta. From these thermodynamic parameters, the binding constant K(L) and enthalpy of binding DeltaH(L), for the weak binding of lysozyme with GlcNAc have been determined. The values of K(L) and DeltaH(L) at pH 5.00 and 298 K are 42 +/- 4 M(-1) and -24 +/- 4 kJ mol(-1), respectively, and agree very well with the experimentally determined values from equilibrium and other studies. The binding constant has also been estimated by simulating the DSC curve with varying values of K(L) (T(d)) until it matches the experimental curve.
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PMID:Differential scanning calorimetric studies on binding of N-acetyl-D-glucosamine to lysozyme. 1702 Aug 56

Phospholipid bilayer coatings can prevent adsorption of cationic proteins on the surface of fused silica capillaries used in capillary electrophoresis. However, the performance of such bilayer coatings is strongly dependent on solution conditions. The factors affecting the rate of formation of phospholipid bilayer coatings were investigated using the double-chained zwitterionic 1,2-dimyristoyl-sn-glycero-phosphocholine (DMPC, C(14)) as a model phospholipid. The effectiveness of these coatings for CE separations of model cationic lysozyme, cytochrome c, ribonuclease A, and alpha-chymotrypsinogen A was also assessed. Increasing the ionic strength of a 0.1 mM DMPC solution reduced capillary coat times from >2 hours in 2.5 mM Tris (pH 7.4) buffer to 3.4 min in 40 mM Tris and dramatically improved separation performance such that > or =1.4 x 10(5) plates/m were observed in capillaries coated for 5 min with 0.1 mM DMPC in 20 mM Tris-HCl (pH 7.4). The presence of Ca(2+) in the coating solution also increases the rate of formation of the phospholipid bilayer coating. The type of vesicle strongly affects its adsorption rate onto the silica surface. The time required to coat the capillary was 7.2 min for small unilamellar vesicles (SUVs) and 22.5 min for large unilamellar vesicles and excessively long for multilamellar vesicles. Highest efficiency protein separations were achieved with bilayer coatings prepared from SUVs. The coating rate was enhanced by using greater DMPC concentrations and unaffected by pH. The type of buffer present in the DMPC coating solution affects the coating behavior, with HEPES buffer yielding a faster coat time than either Tris or phosphate buffers. Histone H1 was separated on a 0.1 mM DMPC-coated capillary.
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PMID:Factors affecting the behavior and effectiveness of phospholipid bilayer coatings for capillary electrophoretic separations of basic proteins. 1823 11

The avian eggshell is a complex, multifunctional biomineral composed of a calcium carbonate mineral phase and an organic phase of lipids and proteins. The outermost layer of the eggshell, the eggshell cuticle, is an organic layer of variable thickness composed of polysaccharides, hydroxyapatite crystals, lipids and glycoprotein. In addition to regulating gas exchanges, the eggshell cuticle may contain antimicrobial elements. In this study, we investigated the antimicrobial activity of eggshell cuticle and outer eggshell protein extracts from four Anseriform species: wood duck (Aix sponsa), hooded merganser (Lophodytes cucullatus), Canada goose (Branta canadensis) and mute swan (Cygnus olor). Cuticle and outer eggshell protein was extracted by urea or HCl treatment of eggs. C-type lysozyme, ovotransferrin and an ovocalyxin-32-like protein were detected in all extracts. Cuticle and outer eggshell protein extracts inhibited the growth of Staphylococcus aureus, Escherichia coli D31, Pseudomonas aeruginosa and Bacillus subtilis. The presence of active antimicrobial proteins within the avian cuticle and outer eggshell suggests a role in antimicrobial defense. Protein extracts from the cavity nesting hooded merganser were especially potent. The unique environmental pressures exerted on cavity-nesting species may have led to the evolution of potent antimicrobial defenses.
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PMID:Antimicrobial activity of the Anseriform outer eggshell and cuticle. 1828 2

1. The eggshell cuticle is the proteinaceous outermost layer of the eggshell which regulates water exchange and protects against entry of micro-organisms. In this study, we investigated the hypothesis that the cuticle may also reduce microbial contamination by providing a chemical defence. 2. Outer eggshell and cuticle protein was extracted from domestic chicken (Gallus gallus), duck (Anas platyrhynchos) and goose (Anser anser) eggs by HCl and urea treatment, respectively. Antimicrobial activity of the extracts against Gram-positive and Gram-negative bacteria was evaluated. 3. C-type lysozyme, ovotransferrin and ovocalyxin-32 were identified in all extracts by Western blotting. All extracts from all species demonstrated lysozyme enzymatic activity. Immobilised c-type lysozyme retained some enzymatic activity. Protein extracts demonstrated activity against Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis suggesting the action of antimicrobial proteins in addition to lysozyme. 4. The results suggest that the antimicrobial outer eggshell and cuticle proteins present in a number of avian species may be a mechanism which enhances avian reproductive success.
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PMID:Antimicrobial activity of cuticle and outer eggshell protein extracts from three species of domestic birds. 1840 87

Spores of Clostridium perfringens possess high heat resistance, and when these spores germinate and return to active growth, they can cause gastrointestinal disease. Work with Bacillus subtilis has shown that the spore's dipicolinic acid (DPA) level can markedly influence both spore germination and resistance and that the proteins encoded by the spoVA operon are essential for DPA uptake by the developing spore during sporulation. We now find that proteins encoded by the spoVA operon are also essential for the uptake of Ca(2+) and DPA into the developing spore during C. perfringens sporulation. Spores of a spoVA mutant had little, if any, Ca(2+) and DPA, and their core water content was approximately twofold higher than that of wild-type spores. These DPA-less spores did not germinate spontaneously, as DPA-less B. subtilis spores do. Indeed, wild-type and spoVA C. perfringens spores germinated similarly with a mixture of l-asparagine and KCl (AK), KCl alone, or a 1:1 chelate of Ca(2+) and DPA (Ca-DPA). However, the viability of C. perfringens spoVA spores was 20-fold lower than the viability of wild-type spores. Decoated wild-type and spoVA spores exhibited little, if any, germination with AK, KCl, or exogenous Ca-DPA, and their colony-forming efficiency was 10(3)- to 10(4)-fold lower than that of intact spores. However, lysozyme treatment rescued these decoated spores. Although the levels of DNA-protective alpha/beta-type, small, acid-soluble spore proteins in spoVA spores were similar to those in wild-type spores, spoVA spores exhibited markedly lower resistance to moist heat, formaldehyde, HCl, hydrogen peroxide, nitrous acid, and UV radiation than wild-type spores did. In sum, these results suggest the following. (i) SpoVA proteins are essential for Ca-DPA uptake by developing spores during C. perfringens sporulation. (ii) SpoVA proteins and Ca-DPA release are not required for C. perfringens spore germination. (iii) A low spore core water content is essential for full resistance of C. perfringens spores to moist heat, UV radiation, and chemicals.
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PMID:Characterization of Clostridium perfringens spores that lack SpoVA proteins and dipicolinic acid. 1846 4

We report observations of the changes in the surface structure of lysozyme adsorbed at the air-water interface produced by the chemical denaturant guanidinium chloride. A primary result is the durability of the adsorbed surface layer to denaturation, as compared to the molecule in the bulk solution. Data on the surface film were obtained from X-ray and neutron reflectivity measurements and modeled simultaneously. The behavior of lysozyme in G.HCl solutions was determined by small-angle X-ray scattering. For the air-water interface, determination of the adsorbed protein layer dimensions shows that at low to moderate denaturant concentrations (up to 2 mol L(-1)), there is no significant distortion of the protein's tertiary structure at the interface, as changes in the orientation of the protein are sufficient to model data. At higher denaturant concentrations, time-dependent multilayer formation occurred, indicating molecular aggregation at the surface. Methodologies to predict the protein orientation at the interface, based on amino acid residues' surface affinities and charge, were critiqued and validated against our experimental data.
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PMID:Effect of the air-water interface on the structure of lysozyme in the presence of guanidinium chloride. 1861 15

On the basis of a sol-gel process, a facile, low cost, and one-step approach for preparing ordered magnetic mesoporous gamma-Fe(2)O(3)/SiO(2) nanocomposites by an evaporation-induced self-assembly (EISA) approach is presented. Various mesostructured silica materials (P6mm or Im3m) incorporated with different amounts of iron oxide (n(Si)/n(Fe) = 9/1, 8/2, 7/3, respectively) were synthesized and characterized by XRD, TEM, N(2)-sorption analyses, and superconducting quantum interference device (SQUID) magnetometer. The HCl-leaching experiments together with TEM micrographs and nitrogen sorption analysis suggested that most of the gamma-Fe(2)O(3) domains of several nanometers were embedded in the silica walls, rather than dispersed in the mesopores, which could cause the significant pore clogging reported in some studies. The release behaviors of lysozyme from these magnetic porous nanocomposites were investigated for the possible application of drug targeting and control release. The influence of iron precursors was also studied and a possible mechanism was proposed. The hydrolysis of Fe(3+) ions under weakly acidic conditions and the induced formation of Si-O-Fe bonds may account for the synthesis of this kind of nanocomposite. These multifunctional nanostructured materials would have a wide range of applications in toxin removal, catalysis, waste remediation, and biological separation as well as novel drug-carrier technologies.
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PMID:Facile synthesis of ordered magnetic mesoporous gamma-Fe2O3/SiO2 nanocomposites with diverse mesostructures. 1868 44

We report a new process of making highly-porous large polymeric microparticles for local drug delivery to the lungs by inhalation. Poly(lactic-co-glycolic acid) (PLGA) microparticles (average diameter, 10-20 microm) were made by the double-emulsion method. To impart favorable aerodynamic properties, an effervescent salt ammonium bicarbonate (ABC) was included in the internal aqueous phase. ABC produced highly-porous structures in the PLGA particles as it escaped as ammonia and carbon dioxide. The fine-particle fraction (FPF) of the microparticles increased as a function of the ratio of ABC to PLGA. Microparticles prepared with 7.5%w/w (ABC/PLGA) had a mass median aerodynamic diameter (MMAD) of 4.0 +/- 1.2 microm and FPF of 32.0 +/- 9.1% when tested with Anderson Cascade Impactor (ACI) and Rotahaler. The highly-porous large particles deposited at the ACI stages corresponding to the trachea and below. The highly-porous large particles avoided phagocytosis by macrophages, while non-porous small particles were quickly taken up by the macrophages. Unlike other encapsulation methods which employ osmogens or extractable porogens, this method could encapsulate lysozyme and doxorubicin.HCl, with high encapsulation efficiency ( approximately 100% for both lysozyme and doxorubicin), in the PLGA microparticles characterized by desirable MMAD (4.5 +/- 0.6 microm lysozyme; 4.6 +/- 0.4 microm doxorubicin) and FPF (29.1 +/- 12.2% lysozyme; 33.8+/-3.6% doxorubicin). Fifty-two percent of encapsulated doxorubicin was released over 4 days from the highly-porous microparticles. This method is an efficient way of making polymeric microparticles for sustained local drug delivery by inhalation.
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PMID:Development of highly porous large PLGA microparticles for pulmonary drug delivery. 1913 45

The relatively new technique of vapor pressure osmometry was utilized to determine the preferential interaction of five common solution additives (arginine HCl, guanidine HCl, glycerol, glucose, and urea) using three different model proteins (BSA, lysozyme, and alpha-chymotrypsinogen). Results for guanidine, glycerol, glucose, and urea are comparable to literature values, which utilized the dialysis/densimetry technique. However, values for arginine differ greatly from literature values, making it unclear what is the nature of arginine-protein interactions. A repeat of the dialysis/densimetry measurements reported in the literature supports the vapor pressure osmometry measurements and reveals a never before seen trend in the interaction of arginine with proteins as a function of concentration. This trend is dependent on the protein size and shows arginine to be unique among solution additives. For concentrations below 0.5 M, arginine has a preferential interaction coefficient near zero (slightly greater than zero for small proteins but decreases as the size of the protein increases), which indicates that arginine is neither strongly bound nor excluded from the protein surface. This trend differs greatly from cosolutes that influence the protein folding equilibrium. However, as the concentration of arginine increases beyond 0.5 M, arginine becomes increasingly excluded. Such behavior might be indicative of the protein surface becoming saturated with arginine, thus causing any additional arginine added to the solution to be excluded from interacting with the surface. All of this behavior is most likely the result of a balance between the affinity arginine has for the peptide backbone and certain amino acids and the repulsion generated by surface tension increment and volume exclusion effects [Arakawa et al. Biophysical Chemistry 2007, 127, 1]. In addition, such behavior may explain why arginine has little effect on protein folding equilibrium but is an effective aggregation suppressor.
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PMID:Investigation of cosolute-protein preferential interaction coefficients: new insight into the mechanism by which arginine inhibits aggregation. 1919 88

The hyperthermophilic archaeon Pyrococcus furiosus (Pf) grows optimally at 100 degrees C and encodes single genes for the Group II chaperonin (Cpn), Pf Cpn and alpha-crystallin homolog, the small Heat shock protein (sHsp). Recombinant Pf Cpn is exceptionally thermostable and remained active in high ionic strength, and up to 3M guanidine hydrochloride (Gdn-HCl). Pf Cpn bound specifically to denatured lysozyme and ATP addition resulted in protection of lysozyme from aggregation and inactivation at 100 degrees C. While complexed to heat inactivated lysozyme, Pf Cpn showed enhanced thermostability and ATPase activity, and increased the optimal temperature for ATPase activity from 90 to 100 degrees C. Protein substrate binding also stabilized the 16-mer oligomer of Pf Cpn in 3M Gdn-HCl and activated ATPase hydrolysis in 3-5M Gdn-HCl. In addition, Pf Cpn recognized and refolded the non-native lysozyme released from Pf sHsp, consistent with the inferred functions of these chaperones as the primary protein folding pathway during cellular heat shock.
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PMID:An exceptionally stable Group II chaperonin from the hyperthermophile Pyrococcus furiosus. 1929 88


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