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 Mg-adenosinetriphosphatase (ATPase) in the thyroidal NaI-treated microsome fraction was activated by treatment with basic polyamino acids or trypsin, but not with acidic polyamino acids and basic proteins such as lysozyme and ribonuclease. The enzyme kinetics showed that the activation of trypsin or poly-L-lysine was due to an increase in the maximal velocity of the hydrolyzing reaction without a change in the affinity of the enzyme for its substrate. A break at about 25 degrees C was observed in the Arrhenius plots of Mg-ATPase in the trypsin- or poly-L-lysine treated preparations, but there was no break in the control preparation. These results suggest that the activating effect of trypsin or poly-L-lysine on Mg-ATPase activity in the thyroidal NaI-treated microsome fraction is related to the lipid environment surrounding the enzyme molecule in the thyroid cell membrane.
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PMID:Characterization of thyroidal membrane-bound Mg-adenosinetriphosphatase activated by trypsin or poly-L-lysine. 153 27

Adsorption isotherms of BSA at the solid-water interfaces have been studied as a function of protein concentration, ionic strength of the medium, pH and temperature using silica, barium sulphate, carbon, alumina, chromium, ion-exchange resins and sephadex as solid interfaces. In most cases, isotherms for adsorption of BSA attained the state of adsorption saturation. In the presence of barium sulphate, carbon and alumina, two types in the isotherms are observed. Adsorption of BSA is affected by change in pH, ionic strength and temperature of the medium. In the presence of metallic chromium, adsorbed BSA molecules are either denatured or negatively adsorbed at the metallic interface. Due to the presence of pores in ion-exchange resins, adsorption of BSA is followed by preferential hydration on resin surfaces in some cases. Sometimes two steps of isotherms are also observed during adsorption of BSA on the solid resins in chloride form. Adsorption of BSA, beta-lactoglobulin, gelatin, myosin and lysozyme is negative on Sephadex surface due to the excess adsorption of water by Sephadex. The negative adsorption is significantly affected in the presence of CaCl2, KSCN, LiCl, Na2SO4, NaI, KCl and urea. The values of absolute amounts of water and protein, simultaneously adsorbed on the surface of different solids, have been evaluated in some cases on critical thermodynamic analysis. The standard free energies (delta G0) of excess positive and negative adsorption of the protein per square meter at the state of monolayer saturation have been calculated using proposed universal scale of thermodynamics. The free energy of adsorption with reference to this state is shown to be strictly comparable to each other. The magnitude of standard free energy of transfer (delta G0B) of one mole of protein or a protein mixture at any type of physiochemical condition and at any type of surface is observed to be 38.5 kJ/mole.
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PMID:Protein adsorption at solid-liquid interfaces: Part IV--Effects of different solid-liquid systems and various neutral salts. 175 29

The adsorption isotherms of different proteins from aqueous solution to the surface of different solids have been compared in the presence of additives such as urea, surfactants and high concentration of various neutral salts. The adsorption isotherms of lysozyme on alumina are not affected much in the presence of 8 M urea showing the rigid structure of lysozyme whereas isotherms of hemoglobin show surface coagulation even in presence of 2 M urea. In presence of 8 M urea, adsorption isotherms of BSA on alumina show two distinct steps. The extent of protein adsorption in the presence of surfactants depends on the nature of surfactants as well as of the underlying surface. The adsorption isotherms of BSA and lysozyme in presence of 2 M concentration of different neutral salts have also been compared with each other. In the presence of denaturants such as NaI and LiCl, the proteins are adsorbed in unfolded beta-conformation whereas in the presence of protein stabilizers such as NaCl, KCl and Na2SO4, amount of protein adsorbed at saturation is zero or extremely small showing that unfolding of proteins at the interface is necessary for initial stage of protein adsorption. The standard free energy change (delta G degrees) per square meter of the surface, signifying relative affinity of adsorption at the state of monolayer saturation, have been calculated. The magnitude of standard free energy of transfer (delta G degrees B) of one mole of protein to the surface in presence of all the additives was found close to 40 kJ/mole.
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PMID:Effect of denaturants and stabilisers on protein adsorption at solid-liquid interfaces. 792 31

Cefdinir, a new oral 2-amino-5-thiazolyl cephalosporin, inhibited the luminol-amplified chemiluminescence (LACL) response of human neutrophils stimulated by PMA but not opsonized zymosan, in a concentration-dependent but not time-dependent manner. The LACL response to opsonized zymosan in cytochalasin B-treated neutrophils was, however, inhibited by cefdinir. Various cephalosporins, regardless of the presence of a 2-amino-5-thiazolyl moiety, did not significantly alter the neutrophil LACL response triggered by PMA and zymosan. The LACL response induced by the calcium ionophore A23187 and FMLP was also impaired by cefdinir, and this impairment was increased in cytochalasin B-treated neutrophils. Superoxide anion generation by neutrophils, measured in terms of lucigenin-amplified chemiluminescence and cytochrome c reduction, was not altered. Spontaneous and FMLP-induced neutrophil degranulation, assessed by lysozyme and beta-glucuronidase release, were not modified by cefdinir. Furthermore, cefdinir inhibited LACL generation in cell-free systems consisting of H2O2, NaI, and either horseradish peroxidase or a myeloperoxidase-containing neutrophil extract. Orthodianisidine oxidation in these two acellular systems was inhibited by cefdinir. Cefdinir did not alter neutrophil bacterial killing at concentrations that inhibited myeloperoxidase-containing neutrophil extract-dependent reactions induced by soluble stimuli. Taken together, these data strongly suggest that cefdinir directly inhibits the activity of myeloperoxidase-containing neutrophil extract released into the extracellular medium during neutrophil stimulation by soluble mediators, but has no effect on that released into the phagolysosome during phagocytosis. This unusual property of a member of the beta-lactam family could be of interest in modulating the exaggerated inflammatory process often associated with infectious diseases.
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PMID:Cefdinir (CI-983), a new oral amino-2-thiazolyl cephalosporin, inhibits human neutrophil myeloperoxidase in the extracellular medium but not the phagolysosome. 813 56

Understanding direct salt effects on protein crystal polymorphism is addressed by comparing different crystal forms (triclinic, monoclinic, tetragonal and orthorhombic) for hen, turkey, bob white quail and human lysozymes. Four new structures of hen egg-white lysozyme are reported: crystals grown in the presence of NapTS diffracted to 1.85 A, of NaI to 1.6 A, of NaNO(3) to 1.45 A and of KSCN to 1.63 A. These new structures are compared with previously published structures in order to draw a mapping of the surface of different lysozymes interacting with monovalent anions, such as nitrate, chloride, iodide, bromide and thiocyanate. An analysis of the structural sites of these anions in the various lysozyme structures is presented. This study shows common anion sites whatever the crystal form and the chemical nature of anions, while others seem specific to a given geometry and a particular charge environment induced by the crystal packing.
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PMID:Structural effects of monovalent anions on polymorphic lysozyme crystals. 1141 60

Mass Spectra of charge states of folded proteins were obtained with nanospray and aqueous solution containing 20 microM the protein (ubiquitin, cytochrome c, lysozyme) and one of the NaA salts NaCl, NaI, NaAc (acetate) (1-10 mM). At very low collision activated decomposition (CAD), the mass spectra of a protein with charge z exhibited a replacement of zH+ with zNa+ and also multiple adducts of NaA. Higher CAD converts the NaA adduct peaks to Na minus H peaks. These must be due to loss of HA where the H was provided by the protein. The degree of HA loss with increasing CAD followed the order I < Cl < Ac. Significantly, the intensity of the ions with n (Na minus H) adducts showed a downward break past an n(MAX) which is equal to the number of acidic residues of the protein plus the charge of the protein. All the observations could be rationalized within the framework of the electrospray mechanism and the charge residue model, which predict that due to extensive evaporation of solvent, the solutes will reach very high concentrations in the final charged droplets. At such high concentrations, positive ions such as Na+, NH4+ form ion pairs with ionized acidic residues and the negative A- form ion pairs with ionized basic residues of the protein. Adducts of Na+, and NaA to backbone amide groups occur also. This reaction mechanism fits all the experimental observations and provides predictions that the number of acidic and basic groups at the surface of the gaseous protein that remain ionized can be controlled by the absence or presence of additives to the solution.
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PMID:Ion-ion and ion-molecule reactions at the surface of proteins produced by nanospray. Information on the number of acidic residues and control of the number of ionized acidic and basic residues. 1597 26

Monte Carlo simulations are used to establish the potential of mean force between two globular proteins in an aqueous electrolyte solution. This potential includes nonelectrostatic contributions arising from dispersion forces first, between the globular proteins, and second, between ions in solution and between each ion and the globular protein. These latter contributions are missing from standard models. The potential of mean force, obtained from simulation, is fitted to an analytic equation. Using our analytic potential of mean force and Barker-Henderson perturbation theory, we obtain phase diagrams for lysozyme solutions that include stable and metastable fluid-fluid and solid-fluid phases when the electrolyte is 0.2 M NaSCN or NaI or NaCl. The nature of the electrolyte has a significant effect on the phase diagram.
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PMID:Effect of salt identity on the phase diagram for a globular protein in aqueous electrolyte solution. 1713 40

Large anions are attracted to hydrophobic surfaces while smaller, well solvated ions are repelled. Using a combination of explicit solvent and continuum model simulations we show that this leads to significant ion-specific protein-protein interactions due to hydrophobic patches on the protein surfaces. In solutions of NaI and NaCl we calculate the potentials of mean force and find that the resulting second virial coefficients for lysozyme correspond well with experiment. We argue that ionic interactions with nonpolar surface groups may play an important role for biomolecular assembly and Hofmeister-type effects.
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PMID:Ion specific protein assembly and hydrophobic surface forces. 1864 9

A recent Monte Carlo simulation determined the potential of mean force between two lysozyme molecules in various aqueous solutions [M. Lund, Phys. Rev. Lett. 100, 258105 (2008)]. The study involved a combination of explicit solvent and continuum model simulations and showed that there are significant ion-specific protein-protein interactions due to hydrophobic patches on the protein surfaces. In this paper we use the results of their study to determine the phase diagram for lysozyme for aqueous solutions of NaCl and NaI. Two of the three phase diagrams have a stable fluid-fluid critical point, while the third has a slightly metastable critical point. This results from a secondary extremum in the potential associated with a repulsive interaction. This repulsive interaction reduces the effective range of the attractive interaction and produces a metastable critical point. We compare the results of one of these phase diagrams with that for a model that includes ion-dispersion forces, but does not contain solvent structural effects.
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PMID:Ion specific effects on phase transitions in protein solutions. 1939 68

It is well-known that the addition of salts influences the properties of proteins in solution. The essential nature of this phenomenon is far from being fully understood, partly due to the absence of the relevant thermodynamic information. To help fill this gap, in this work isothermal titration calorimetry (ITC) was employed to study the ion-lysozyme association in aqueous buffer solutions at pH = 4.0. ITC curves measured for NaCl, NaBr, NaI, NaNO3, NaSCN, KCl, CaCl2, and BaCl2 salts at three different temperatures were described by a model assuming two sets of independent binding sites on the lysozyme. The resulting thermodynamic parameters of binding of anions (counterions) to the first class of sites (N approximately 7) indicate that the binding constant (K approximately 102 M-1) increases in the order Cl- < Br- < I- < NO3- < SCN-. The anion-lysozyme association is entropy driven, accompanied by a small favorable enthalpy contribution and a positive change in heat capacity. It seems that the entropy and heat capacity increase is due to the water released upon binding, while the net exothermic effect originates from the anion-NH3+ pair formation. Moreover, the results reveal that the nature of the cation has little effect on the thermodynamics of the anion-lysozyme association under the given experimental conditions. Taken together, it seems that the observed thermodynamics of association is a result of a combination of both electrostatic and short-range interactions. The anion ordering reflects the strength of water mediated interactions between anions and lysozyme.
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PMID:Thermodynamics of the lysozyme--salt interaction from calorimetric titrations. 2021 69


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