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)

Tubulin can stimulate specifically the aryl phosphatase activity of the low-Mr polycation-stimulated (PCSL) phosphatase, measured as p-nitrophenyl phosphatase activity, or using reduced carboxamidomethylated and maleylated (RCM) lysozyme, phosphorylated on tyrosyl residues, as a substrate. This stimulation is independent of the degree of polymerization of tubulin (A50 = 60 nM) and is due to an increase in Vmax. It is mechanistically different from the ATP-induced activation and resistant to heat and trypsin treatment. Chymotrypsin destroys the stimulatory effect of tubulin. The polycation-stimulated phosphorylase phosphatase activity is inhibited by tubulin, probably by a polycation/polyanion interaction. The microtubule-associated protein, MAP2, is inhibitory to the p-nitrophenyl phosphatase activity and tubulin can eliminate this inhibitory effect. MAP2 also inhibits the polycation-stimulated phosphorylase phosphatase activity.
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PMID:Tubulin and MAP2 regulate the PCSL phosphatase activity. A possible new role for microtubular proteins. 254 1

Octadecyl-bonded silica, commonly used for reverse-phase high-pressure liquid chromatography, was modified using surfactants bearing ionizable groups and the modified packing used in ion-exchange chromatography of proteins. The surfactants 2-(n-hexadecylheptaethoxy)acetic acid, 1-(n-hexadecyloctaethoxy)ethylene-diamine, and N-(n-hexadecyloctaethoxy)pyridinium were adsorbed onto test columns packed with octadecyl-bonded silica particles. The proteins lysozyme, bovine serum albumin, trypsin, horse serum cholinesterase, and bovine liver carboxylesterase were used to study the ion-exchange characteristics of the modified packings. The retention order of the proteins on the surfactant-modified stationary phases were as predicted by the isoelectric point of each protein. In addition, the interaction of enzymes with the packings did not result in significant loss of enzymatic activity. Surfactant removal was possible with the use of organic solvents and this allowed the octadecyl-bonded surface to be used again in the reverse-phase mode. During the course of the experiments, no degradation in the packing's performance was observed due to loss of adsorbed surfactant, even after over 85,000 column volumes of sodium chloride and Tris-HCl buffers were circulated through the column.
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PMID:Reversible conversion of octadecyl-bonded silica to ion-exchange surfaces for protein separations. 254 Jun 75

A method of calculating the electrostatic potential energy between two molecules, using finite difference potential, is presented. A reduced charge set is used so that the interaction energy can be calculated as the two static molecules explore their full six-dimensional configurational space. The energies are contoured over surfaces fixed to each molecule with an interactive computer graphics program. For two crystal structures (trypsin-trypsin inhibitor and anti-lysozyme Fab-lysozyme), it is found that the complex corresponds to highly favourable interacting regions in the contour plots. These matches arise from a small number of protruding basic residues interacting with enhanced negative potential in each case. The redox pair cytochrome c peroxidase-cytochrome c exhibits an extensive favourably interacting surface within which a possible electron transfer complex may be defined by an increased electrostatic complementarity, but a decreased electrostatic energy. A possible substrate transfer configuration for the glycolytic enzyme pair glyceraldehyde phosphate dehydrogenase-phosphoglycerate kinase is presented.
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PMID:Investigating protein-protein interaction surfaces using a reduced stereochemical and electrostatic model. 254 Dec 55

Some properties of Morganella morganii bacteriocins were determined. For this purpose two strains (115 and 137) which after mitomycin C induction produced bacteriocins in high titer were chosen. The influence of several physical and chemical factors such as: heating and storage at various temperatures, a freezing and thawing, an influence of buffered fluid of different pH, and digestion by trypsin, papain and lysozyme were investigated. Range of bacteriocin activity against various microorganisms and the ability to diffuse in agar were also determined. It was found on the basis of the results obtained that two bacteriocins showed different features. Bacteriocin "115" was thermostable, sensitive to proteolytic enzymes, able to diffuse in 1.5% agar. Bacteriocin designated "137" was thermolabile, intensive to proteolytic digestion, and incapable to diffuse in 1.5% agar. Activity of both bacteriocins was reduced after freezing and thawing. They were both insensitive to lysozyme digestion. Storage at room temperature reduced their activity faster than storage at the temperature of refrigerator. Their activity was completely stopped at pH 3.03, and significantly at pH 5.08 while environment of pH ranged from 7.08 to 11.0 did not influence their activity. Both bacteriocins showed narrow range of activity limited to the growth inhibition of sensitive strains belonging to Morganella morganii genus.
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PMID:[Properties of bacteriocins of Morganella morganii]. 266 59

A group A streptococcal strain demonstrated binding activities for 125I-murine IgG3 and 125I-human IgG. This 125I-murine IgG3 binding could be inhibited by unlabelled equine IgG but not by IgG from cattle, chickens and dogs, indicating binding properties of IgG Fc-receptors of type II. In contrast to binding sites of Streptococcus dysgalactiae (serogroup C) carrying type III IgG Fc-receptors, the binding sites of the group A streptococcus appeared to be antigenically different, extremely sensitive to trypsin and did not show any cross reactions with human albumin. The group A and group C streptococcal binding sites could be solubilized by lysozyme treatment of the bacteria and subsequently isolated by affinity chromatography on human IgG-Sepharose. Further analysis of the group A and group C streptococcal binding proteins by SDS-PAGE and Western blotting revealed numerous, almost identical protein bands with binding activities for 125I-murine IgG3.
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PMID:Interaction of type II IgG Fc-receptors from streptococci of serological group A with murine IgG. 268 6

Bacillus thuringiensis serovar, thuringiensis (HD-2) demonstrated antibacterial activity against 48 of 56 strains of B. thuringiensis and against some other Gram-positive species but not against Gram-negative species. The antibacterial activity was not inducible by mitomycin C or by ultraviolet irradiation, and additional activity was not liberated from cells by sonication. Upon dilution of the antibacterial substance, zones of inhibition diminished without the appearance of plaques. Gel filtration chromatography indicated an Mr greater than 950,000 for the bacteriocin (thuricin) in its native form. The native thuricin was sedimented by ultracentrifugation, but electron microscopy of the pellet failed to reveal phage particles or phage components. Nondenaturing polyacrylamide gel electrophoresis (PAGE) of thuricin demonstrated the association of bacteriocin activity with a protein band which migrated only slightly into a 5% gel. Sodium dodecyl sulfate (SDS)-PAGE of partially purified thuricin revealed five major bands. Thuricin activity was substantially reduced by treatment with chymotrypsin, pronase, subtilisin, trypsin, and heat at 96 degrees C but not by treatment with lysozyme, phospholipase C, papain, peptidase, or organic solvents. It exhibited a bactericidal and bacteriolytic effect on a sensitive strain, B. thuringiensis serovar, canadensis (MF4). Partially purified preparations of thuricin had phospholipase A activity which was adsorbed by sensitive cells but not by cells which were insensitive to thuricin. Antibacterial activity was blocked by preincubation of thuricin with phospholipid. Loss of a 150-mDa plasmid was correlated with loss of thuricin production.
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PMID:Thuricin: the bacteriocin produced by Bacillus thuringiensis. 272 45

The interaction of tryptophan, lysozyme and tyrosine with ninhydrin in strong acid media has been investigated at 20, 25, 30, and 35 degrees C by spectrophotometry. Second-order rate constants and molar absorptivity values have been evaluated from an analytical point of view. Optimum conditions for the selective estimation of tryptophan, tryptophan residues in intact proteins, and indoles--without the disturbing effect of tyrosine--have been given. Under optimum conditions, in the concentration range from 2.5 X 10(-8) to 3.0 X 10(-7)M, molar absorptivity values and reproducibility data for various reactants have been reported. Molar absorptivity values (Am X 10(-3)/M X cm) of tryptophan (21.35), lysozyme (19.33), bovine serum albumin (21.05), human serum albumin (21.00), casein (17.85), alpha-chymotrypsin (18.28), trypsin (14.43), indole (5.03), and indole-3-acetic acid (13.75) have been measured with a standard error of 2.3% or less for any particular reactant.
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PMID:Spectrophotometric determination of tryptophan in intact proteins by the acid ninhydrin method. 274 46

Surface proteins of nine Campylobacter jejuni strains belonging to three different serovia were extracted with lysozyme/ethylenediamine-tetraacetic acid. The preparations bound to isolated murine small intestinal cells and to a membrane fraction (MF) of isolated brush borders obtained by detergent treatment with Triton X-100 and Nonidet P40. Binding was demonstrated by an enzyme-linked immunosorbent assay procedure. Using lipopolysaccharide (LPS)- and flagella-specific antisera the contribution of flagella and LPS, present in the protein preparations, to the total binding to MF was investigated. Only up to approximately 10% of the total binding of each strain was found to be mediated by LPS, 10%-33% of binding was flagella dependent. The preparations of four strains (serovar HS2) bound in a trypsin-sensitive manner (45%-85% reduction), while the others (serovaria HS1 and HS13) were hardly influenced by trypsin treatment. Binding to MF was not impaired by preincubation of the bacterial surface protein preparations with several sugars and lectins.
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PMID:In vitro binding of Campylobacter jejuni surface proteins to murine small intestinal cell membranes. 274 90

The flexibility plot of a protein lies on the observation that amino acid residues with the highest turn potential, i.e. located in highly mobile regions of protein surface, also possess the smallest volumes as well as the lowest hydrophobicities. The plot is generated by shifting a five residue window along the protein sequence and calculating the value of the hydrophobicity-volume product for consecutive quintuplets of amino acid residues. The concomitant occurrence of small volumes and low hydrophobicities results in very deep minima. A threshold value has also been introduced in order to discriminate significant minima. To substantiate the interpretation that the selected minima actually indicate very flexible segments of a protein (loops, turns, etc.), we have compared plots obtained for model proteins (lysozyme, myoglobin, ribonuclease, trypsin, thermolysin and T4 lysozyme) with X-ray thermal factors profiles available for the same proteins. When compared to thermal profiles, the majority of flexible segments evidenced by our plots have been found to be in agreement with regions characterized by high thermal factors. Results have also been discussed in the light of local organization possessed by examined proteins.
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PMID:Flexibility plot of proteins. 274 66

Both human lysozyme (HL) and hen egg white lysozyme (HEWL) inhibited the proliferative response of peripheral blood lymphocytes to T cell mitogens such as the lectins phytohemagglutinin and concanavalin A. This inhibition was observed both when HL or HEWL was added to the lymphocyte cultures in combination with phytohemagglutinin or concanavalin A and when lymphocytes were pretreated with either lysozyme and extensively washed prior to culture with mitogens. Under both conditions, the effects were strictly dose dependent; the lysozyme concentrations yielding maximal inhibitory effect were 5 micrograms/ml for HL and 1 microgram/ml for HEWL, while both lower and higher concentrations were less effective. Specific antilysozyme rabbit sera completely prevented the inhibitory effects of both HL and HEWL on the proliferative response of lymphocytes to phytohemagglutin or concanavalin A. Chitotriose (a lysozyme inhibitor) caused a strong reduction in the inhibitory effects of the two lysozymes on the lymphocyte response to either lectin. HL and HEWL also were found to markedly inhibit the polyclonal B cell proliferation and differentiation induced by pokeweed mitogen and T cells. A less marked inhibition was also obtained when T cells, but not B cells, were pretreated with HL or HEWL. Again, as in the experiments with T cell mitogens, the effects were dose dependent and 5 micrograms/ml HL and 1 microgram/ml HEWL proved to be the most effective concentrations. The possible mechanisms by which lysozyme inhibits the lymphocyte response to mitogenic lectins are considered and discussed. The enzymatic activity seemed to perform an essential function, as shown by the loss of effect when the heat- or trypsin-inactivated lysozymes were used and by the fact that only the enzymatically active compound, among certain semisynthetic derivatives of HEWL, inhibited the lymphocyte response to the mitogens. However, the cationic properties of the lysozyme molecule appeared to be essential too, since enzymes with a similar specificity of action showed effects similar to those observed with HL or HEWL only when they carried a strong positive charge. It is suggested that lysozyme, which is naturally secreted by monocytes and macrophages, might interact with lymphocyte surface receptor sites and participate in the complex mononuclear phagocyte-lymphocyte interactions and in the modulation of lymphocyte activation.
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PMID:Lysozyme-induced inhibition of the lymphocyte response to mitogenic lectins. 291 8


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