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)

This paper describes the photosynthesis of gold nanoparticles (GNPs) in the presence of bovine serum albumin (BSA). The concentration of NaAuCl4 and the relative ratio of NaAuCl4 to BSA are important parameters for controlling the size of the GNPs. We prepared GNPs having average diameters ranging from 7 to 50 nm by illumination (Hg-Xe lamp) of phosphate-buffered solutions (pH 3.0-11.0) containing 1 mM NaAuCl4 and 10 microM BSA for 9 h. The size distribution of the GNPs synthesized at pH 7.0 is narrower relative to that of those prepared at other values of pH. Based on the observation that there are no GNPs formed at 25 degrees C in the absence of either BSA or illumination, we conclude that photolytic reduction is the main mechanism for the formation of the GNPs and that BSA acts as a capping agent to stabilize the as-synthesized GNPs. In addition to BSA, several other proteins, such as beta-casein, conalbumin, hemoglobin, beta-lactoglobulin, lysozyme, myoglobin, ovalbumin, pepsin, and trypsinogen play the same role.
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PMID:Photosynthesis of gold nanoparticles in presence of proteins. 1643 Jan 51

Photonic induced immobilization is a novel technology that results in spatially oriented and spatially localized covalent coupling of biomolecules onto thiol-reactive surfaces. Immobilization using this technology has been achieved for a wide selection of proteins, such as hydrolytic enzymes (lipases/esterases, lysozyme), proteases (human plasminogen), alkaline phosphatase, immunoglobulins' Fab fragment (e.g., antibody against PSA [prostate specific antigen]), Major Histocompability Complex class I protein, pepsin, and trypsin. The reaction mechanism behind the reported new technology involves "photonic activation of disulfide bridges," i.e., light-induced breakage of disulfide bridges in proteins upon UV illumination of nearby aromatic amino acids, resulting in the formation of free, reactive thiol groups that will form covalent bonds with thiol-reactive surfaces (see Fig. 1). Interestingly, the spatial proximity of aromatic residues and disulfide bridges in proteins has been preserved throughout molecular evolution. The new photonic-induced method for immobilization of proteins preserves the native structural and functional properties of the immobilized protein, avoiding the use of one or more chemical/thermal steps. This technology allows for the creation of spatially oriented as well as spatially defined multiprotein/DNA high-density sensor arrays with spot size of 1 microm or less, and has clear potential for biomedical, bioelectronic, nanotechnology, and therapeutic applications.
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PMID:Photonic activation of disulfide bridges achieves oriented protein immobilization on biosensor surfaces. 1643 46

The solubility of non cross-linked chitosan in weak acid solutions restricts its utility in microspheres for drug delivery. The primary aim of this study was to produce pentasodium tripolyphosphate cross-linked chitosan microspheres with higher acid resistance for controlled release of ampicillin. The microspheres were prepared by two different microencapsulation procedures (by emulsification and by spray-drying) and characterized by their particle size, surface morphology, stability, drug entrapment efficiency and drug release. The size of the microspheres was <10 microm with a narrow size distribution. The entrapment of ampicillin in the microspheres was more than 80%. Stability of uncross-linked and cross-linked microspheres was affected by the pH of simulated gastric fluid (SGF, pH 1.2) and simulated intestinal fluid (SIF, pH 7.5). The inclusion of the enzymes pepsin and pancreatin did not affect the stability of the microspheres. The inclusion of lysozyme in phosphate buffer saline resulted in increased solubilization. The release of the drug was affected by cross-linking of microspheres with tripolyphosphate (TPP). The cross-linked microspheres were more stable in simulated gastric fluid and showed slower but sustained release of ampicillin. The antimicrobial activity of the released ampicillin was confirmed by Staphylococcus aureus bioassay.
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PMID:Ionotropic cross-linked chitosan microspheres for controlled release of ampicillin. 1649 52

Lactobacillus strains from traditional African fermented milk products, as well as human intestinal isolates were identified and investigated in vitro for their technological and functional characteristics as potential new probiotic strains. To test survival under gastrointestinal conditions, first the protective effect of milk and the effects of medium composition, lysozyme, pepsin, and pH of the medium on bacterial viability were assessed in vitro using the Plackett-Burman statistical model and the commercially used L. johnsonii LA1 probiotic strain. The use of either an artificial gastric electrolyte solution or MRS did not play a significant role in the viability of the cultures, while lysozyme, acidic conditions (pH 2.5), pepsin and the presence of milk significantly influenced the survival of the strain. Therefore, these parameters were selected as important test variables in a model stomach passage survival trial. Five strains identified as L. plantarum and two identified as L. johnsonii showed good survival under simulated gastrointestinal conditions. These selected strains also showed antimicrobial activity, probably due to production of organic acids. All strains exhibited bile salt hydrolase activity, while only the L. plantarum strains showed beta-galactosidase activity.
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PMID:Lactobacillus spp. with in vitro probiotic properties from human faeces and traditional fermented products. 1650 61

Human lysozyme variants form amyloid fibrils in individuals suffering from a familial non-neuropathic systemic amyloidosis. In vitro, wild-type human and hen lysozyme, and the amyloidogenic mutants can be induced to form amyloid fibrils when incubated under appropriate conditions. In this study, fibrils of wild-type human lysozyme formed at low pH have been analyzed by a combination of limited proteolysis and Fourier-transform infrared (FTIR) spectroscopy, in order to map conformational features of the 130 residue chain of lysozyme when embedded in the amyloid aggregates. After digestion with pepsin at low pH, the lysozyme fibrils were found to be composed primarily of N and C-terminally truncated protein species encompassing residues 26-123 and 32-108, although a significant minority of molecules was found to be completely resistant to proteolysis under these conditions. FTIR spectra provide evidence that lysozyme fibrils contain extensive beta-sheet structure and a substantial element of non beta-sheet or random structure that is reduced significantly in the fibrils after digestion. The sequence 32-108 includes the beta-sheet and helix C of the native protein, previously found to be prone to unfold locally in human lysozyme and its pathogenic variants. Moreover, this core structure of the lysozyme fibrils encompasses the highly aggregation-prone region of the sequence recently identified in hen lysozyme. The present proteolytic data indicate that the region of the lysozyme molecule that unfolds and aggregates most readily corresponds to the most highly protease-resistant and thus highly structured region of the majority of mature amyloid fibrils. Overall, the data show that amyloid formation does not require the participation of the entire lysozyme chain. The majority of amyloid fibrils formed from lysozyme under the conditions used here contain a core structure involving some 50% of the polypeptide chain that is flanked by proteolytically accessible N and C-terminal regions.
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PMID:Identification of the core structure of lysozyme amyloid fibrils by proteolysis. 1685 5

Lactobacillus plantarum N014 was isolated from nham, a traditional Thai fermented pork, and exhibited antimicrobial activity against Listeria monocytogenes. Its bacteriocin had a broad inhibitory spectrum toward both gram-positive and gram-negative bacteria. The bacteriocin activity was sensitive to all proteolytic enzymes used in this study, including papain, pepsin, pronase E, proteinase K, and trypsin, but was resistant to the other enzymes, such as alpha-amylase, lipase A, and lysozyme. Furthermore, activity was stable over various heat treatments and pH values. The bacteriocin exerted a bacteriolytic mode of action. It was produced during the exponential growth phase and reached its highest level as producer cells entered the stationary phase. Adsorption of the bacteriocin onto producer cells was pH-dependent. No bacteriocin adsorption was detected at pH 1 to 3, whereas 100% bacteriocin adsorption was found at pH 7. Plasmid isolation revealed that L. plantarum N014 contained no plasmids. From Tricine-sodium dodecyl sulfate-polyacrylamide gel electrophoresis and growth inhibition testing against L. monocytogenes, the estimated molecular mass of L. plantarum N014 bacteriocin was 8 kDa.
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PMID:Isolation and preliminary characterization of a bacteriocin produced by Lactobacillus plantarum N014 isolated from nham, a traditional Thai fermented pork. 1692 20

The chaperonin GroEL of the heat shock protein family from Escherichia coli cells can bind various polypeptides lacking rigid tertiary structure and thus prevent their nonspecific association and provide for acquisition of native conformation. In the present work we studied the interaction of GroEL with six denatured proteins (alpha-lactalbumin, ribonuclease A, egg lysozyme in the presence of dithiothreitol, pepsin, beta-casein, and apocytochrome c) possessing negative or positive total charge at neutral pH values and different in hydrophobicity (affinity for a hydrophobic probe ANS). To prevent the influence of nonspecific association of non-native proteins on their interaction with GroEL and make easier the recording of the complexing, the proteins were covalently attached to BrCN-activated Sepharose. At low ionic strength (lower than 60 mM), tight binding of the negatively charged denatured proteins with GroEL (which is also negatively charged) needed relatively low concentrations (approximately 10 mM) of bivalent cations Mg2+ or Ca2+. At the high ionic strength (approximately 600 mM), a tight complex was produced also in the absence of bivalent cations. In contrast, positively charged denatured proteins tightly interacted with GroEL irrespectively of the presence of bivalent cations and ionic strength of the solution (from 20 to 600 mM). These features of GroEL interaction with positively and negatively charged denatured proteins were confirmed by polarized fluorescence (fluorescence anisotropy). The findings suggest that the affinity of GroEL for denatured proteins can be determined by the balance of hydrophobic and electrostatic interactions.
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PMID:Affinity chromatography of GroEL chaperonin based on denatured proteins: role of electrostatic interactions in regulation of GroEL affinity for protein substrates. 1722 89

Human milk samples from three healthy donors were investigated in order to evaluate the antibacterial activity during lactation against Escherichia coli ATCC 25922 and Listeria monocytogenes. The concentration of the main human-milk antimicrobial proteins (lactoferrin (LF), lysozyme (LZ) and secretory immunoglobulin A (sIgA)) was determined by ELISA. Results showed that human milk exhibited antibacterial activity against List. monocytogenes, although it was weakly active against Esch. coli ATCC 25922. The observed antilisterial activity was positively correlated with LZ concentration. In addition, the effect of gastrointestinal proteases, at different pH conditions, that prevail in the stomach of infants (pH 2.0-6.5), on antilisterial activity and protein degradation was evaluated. Hydrolysis with pepsin at pH 4.0-6.5, followed by treatment with pancreatic enzymes, resulted in a decreased hydrolysis of LZ, LF and sIgA and an enhanced antibacterial activity against List. monocytogenes. It is suggested that partial degradation of certain milk proteins at the gastrointestinal level may produce peptides that could act synergistically with the remnant intact proteins.
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PMID:Activity against Listeria monocytogenes of human milk during lactation. A preliminary study. 1822 4

Besides the specific chitinase, chitosanase and lysozyme, chitosan also could be hydrolyzed by some non-specific enzymes such as cellulase, protease, lipase and pepsin, especially cellulase, which show high activity on chitosan. Almost all the cellulases produced by different kinds of microorganisms could degrade chitosan to chitooligomers. The existence of bifunctional enzymes with cellulase and chitosanase activity is one of the reasons for cellulase on chitosan hydrolysis. The bifunctional cellulase-chitosanases mainly belong to glycoside hydrolase family 8 (GH-8), few belong to GH-5 and GH-7, according to the homogeneity analysis of amino acids sequences. Their three dimensional structures however have not been clearly determined. This paper may serve as a guide for a further study on the relationship between structure and function of chitosanolytic cellulases.
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PMID:Advance in chitosan hydrolysis by non-specific cellulases. 1832 93

Flux and retention of 0.1%w/w aqueous solutions of several proteins [lysozyme, pepsin, bovine serum albumin (BSA), lipase, and gamma-globulin] with molecular weights of 14.6, 36, 67, 801 and 150 kDa are studied when they are tangentially filtered, with transmembrane pressure differences until 1 MPa and circulation velocities in the re-tentate loop from 0.04 to 1.98 m/s (laminar regime), through two asymmetric polysulfone commercial membranes (E-100 with a nominal pore size of 0.01 mum and E-500 with a nominal pore size of 0.04 mum). Results are analyzed with the film theory for the concentration-polarization phenomenon, obtaining the mass transfer coefficient along with the apparent and true retention coefficients for the cell used, as a function of the feed circulation velocity and the molecular weight of the solute. The standard retention curves lead to pore size distributions differing from the nominal ones. These differences can be attributed to the modifications of the membranes when they are in operational conditions, probably due to protein adsorption. (c) 1995 John Wiley & Sons, Inc.
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PMID:Cross-flow ultrafiltration of proteins through asymmetric polysulfonic membranes: I. Retention curves and pore size distributions. 1862 42


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