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)

The interaction of metal cations with single chain globular proteins produces volume increases, the magnitude of which is determined primarily by the ion and to a lesser extent by the protein. The cations are listed in ascending order of volume change: K(I) less than Mg(II) less than Sr(II) less than Ca(II) less than Co(II) less than Ni(II) less than Cd(II) less than Zn(II) less than Cu(II) less than Pb(II). This sequence held for all cation-protein systems investigated except for Cd(II) which produced a slightly larger volume effect than Zn(II) with lysozyme. The volume changes attributed to protein-cation interaction are positive and range from 8 ml/10(5) g of protein for the reaction on 0.05 M KNO3 with bovine plasma albumin to 2320 ml/10(5) g of protein produced by the 0.20 M Pb(NO3)2-myoglobin system. A similar classification scheme was not possible for the proteins. For example, volume increases of 45, 50, 80 and 95 ml/10(5) g of protein were produced when 0.05 M Mg(II) reacted with bovine serum albumin, ovalbumin, sperm whale myoglobin and lysozyme, respectively. However, when 0.2 M Pb(II) was the reactant the values were 1930, 846, 2320, and 1120 ml/10(5) g of protein. Volume effects produced by Cr(III), Al(III) and Fe(III) were determined, but the calculated results are considered dubious because the volume changes are a complicated function of protein-cation and protein-proton interaction.
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PMID:Protein-metal ion interaction: volume effects produced by the interaction of proteins with metal ions. 105 36

We have used equilibrium binding analyses to evaluate the influence of temperature and urea on the affinity of hen egg white lysozyme and bovine pancreatic ribonuclease A for surface-immobilized Cu(II) ions. Linear Scatchard plots suggested that these model proteins were interacting with immobilized metal ions via a single class of intermediate-affinity (Kd = 10-40 microM) binding sites. Alterations in temperature had little or no effect on the immobilized Cu(II) binding capacity of either protein. Temperature effects on the interaction affinity, however, were protein-dependent and varied considerably. The affinity of lysozyme for immobilized Cu(II) ions was significantly decreased with increased temperature (0 degree C-37 degrees C), yet the affinity of ribonuclease did not vary measurably over the same temperature range. The van 't Hoff plot (1n K vs 1/T) for lysozyme suggests a straight line relationship (single mechanism) with a delta H of approximately -5.5 kcal/mol. Urea effects also varied in a protein-dependent manner. A 10-fold reduction in the affinity of lysozyme for the immobilized Cu(II) was observed with the urea concentrations up to 3 M; yet urea had no effect on the affinity of ribonuclease for the immobilized metal ions. Although the interaction capacity of lysozyme with the immobilized Cu(II) ions was decreased by 50% in 3 M urea, ribonuclease interaction capacity was not diminished in urea. Thus, temperature- and urea-dependent alterations in protein-metal ion interactions were observed for lysozyme but not ribonuclease A. The complete, yet reversible, inhibition of lysozyme- and ribonuclease-metal ion interactions by carboxyethylation with low concentrations of diethylpyrocarbonate provided direct evidence of histidyl involvement. The differential response of these proteins to the effects of temperature and urea was, therefore, interpreted based on calculated solvent-accessibilities and surface distributions of His residues, individual His residue pKa values, and specific features of the protein surface structure in the immediate environment of the surface-exposed histidyl residues. Possible interaction mechanisms involved in protein recognition of macromolecular surface-immobilized metal ions are presented.
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PMID:Protein interactions with surface-immobilized metal ions: structure-dependent variations in affinity and binding capacity with temperature and urea concentration. 185 19

Significant quantities of Ag(I), Cu(II), and Cr(III) were bound to isolated Bacillus subtilis 168 walls, Escherichia coli K-12 envelopes, kaolinite and smectite clays, and the corresponding organic material-clay aggregates (1:1, wt/wt). These sorbed metals were leached with HNO3, Ca(NO3)2, EDTA, fulvic acid, and lysozyme at several concentrations over 48 h at room temperature. The remobilization of the sorbed metals depended on the physical properties of the organic and clay surfaces and on the character and concentration of the leaching agents. In general, the order of remobilization of metals was Cr much less than Ag less than Cu. Cr was very stable in the wall, clay, and composite systems; pH 3.0, 500 microM EDTA, 120-ppm [mg liter-1] fulvic acid, and 160-ppm Ca remobilized less than 32% (wt/wt) of sorbed Cr. Ag (45 to 87%) and Cu (up to 100%) were readily removed by these agents. Although each leaching agent was effective at mobilizing certain metals, elevated Ca or acidic pH produced the greatest overall mobility. The organic chelators were less effective. Lysozyme digestion of Bacillus walls remobilized Cu from walls and Cu-wall-kaolinite composites, but Ag, Cr, and smectite partially inhibited enzyme activity, and the metals remained insoluble. The extent of metal remobilization was not always dependent on increasing concentrations of leaching agents; for example, Ag mobility decreased with some clays and some composites treated with high fulvic acid, EDTA, and lysozyme concentrations. Sometimes the organic material-clay composites reacted in a manner distinctly different from that of their individual counterparts; e.g., 25% less Cu was remobilized from wall- and envelope-smectite composites than from walls, envelopes, or smectite individually in 500 microM EDTA. Alternatively, treatment with 160-ppm Ca removed 1.5 to 10 times more Ag from envelope-kaolinite composites than from the individual components. The particle size of the deposited metal may account for some of the stability changes; those metals that formed large, compact aggregates (Cr and Ag) as seen by transmission electron microscopy were less likely to be remobilized. In summary, it is apparent that remobilization of toxic heavy metals in sediments, soils, and the vadose zone is a complicated issue. Predictions based on single inorganic or organic component systems are too simplistic.
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PMID:Remobilization of toxic heavy metals adsorbed to bacterial wall-clay composites. 212 2

We have examined the influence of free metal ions on the affinity of structurally-defined proteins and peptides for model surface-immobilized metal ions. The model proteins chosen differed widely in both the type and quantity of surface-accessible electron donor groups. Metal ion affinity chromatography and equilibrium binding analyses demonstrated that the presence of excess free Cu(II) ions did not measurably affect either the affinity or the binding capacity of lysozyme for immobilized iminodiacetate-Cu(II). Similarly, the presence of excess free Cu(II) ions did not detectably affect the chromatographic behavior or measured affinity of either copper-saturated lactoferrin or iron-saturated lactoferrin for the immobilized Cu(II) ions. Its binding capacity however, was diminished. The affinities of small peptides for immobilized Cu(II) ions was found to be related to their number of His residues. Peptides with 0, 1, 2 and 3 His residues were resolved by high-performance immobilized Cu(II) affinity chromatography in both the presence and absence of added Cu(II) ions. In the presence of excess free Cu(II) ions, however, retention (affinities) of these peptides by immobilized Cu(II) ions was increased in relation to their number of His residues. These data demonstrate that protein surface binding sites for free and immobilized metal ions are functionally distinct. The presence of free and/or protein surface-bound metal ions does not preclude interaction with the same immobilized metal ions. Stationary phase immobilized metal ions can be a useful model system through which we can better understand the influence of macromolecular surface-immobilized metal ions on macromolecular recognition events. The significance of these findings are also important to the design of other site-specific and domain-specific affinity reagents involving metal ions.
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PMID:Differential interaction of peptides and protein surface structures with free metal ions and surface-immobilized metal ions. 232 49

We have compared the oxidative renaturation of reduced hen egg white lysozyme promoted by Cu(II) + O2 with that promoted by a glutathione redox buffer. The progress curves for protein fluorescence, circular dicroism, thiol oxidation, hydrodynamic volume, and enzymic activity were determined for both regeneration systems. All of these processes were more rapid in the glutathione regeneration than in the copper-catalyzed. Comparison of the two systems was carried out by normalizing the progress curves with a coordinate system where "time" is replaced by "extent of protein thiol oxidation." While similar progress curves were obtained for circular dichroism, the two systems produced distinctly different progress curves for enzymic activity, fluorescence, and gel permeation chromatographic reflection of protein hydrodynamic volume. We infer that all these differences result from differences in relative amounts and/or kind of reaction intermediates. Thus, there are substantial differences between the renaturation mechanisms of the glutathione- and the copper-promoted systems.
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PMID:Multiple parameter kinetic studies of the oxidative folding of reduced lysozyme. 661 47

The interaction between hen egg-white lysozyme and Cu(II) or Co(II) cations has been studied by dilatometry, equilibrium dialysis-differential refractometry and viscometry at different metal cation concentrations. Delta V isotherms in copper and cobalt solutions have been obtained from dilatometry. Preferential adsorption parameters and specific viscosity have been determined from refractometric and viscosimetric measurements. It has been observed that this interaction produces structural alterations in lysozyme. The magnitude of these conformational changes depends on the metal ion and protein concentration. The results obtained using the three techniques are in good agreement.
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PMID:Dilatometric, refractometric and viscometric study of lysozyme-cation interaction. 732 52

Riboflavin is known to generate superoxide anion upon photoillumination and in the presence of Cu(II) causes fragmentation of DNA. In the present study we examined the effect of riboflavin and Cu(II) on bovine serum albumin, invertase and lysozyme. Using fluorescence quenching experiments, it is shown that riboflavin binds to protein and causes fragmentation which in the presence of Cu(II) is enhanced. Using neocuproine as the Cu(I) sequestering reagent, it has also been shown that Cu(I) is an essential intermediate in the protein fragmentation reaction. Results obtained with various scavengers of active oxygen species strongly suggest that the species predominantly responsible for protein breakage is hydroxyl radical.
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PMID:Enhanced protein degradation by photoilluminated riboflavin in the presence of Cu(II). 770 5

A new procedure has been developed to immobilize iminodiacetic acid (IDA) onto the surface of silica supports, such as LiChrospher Si-1000 and 1.5-microns nonporous silica, for use in high-performance immobilized metal affinity chromatography (HPIMAC) of proteins. This IDA immobilization method has been achieved through the synthesis of a new silylation reagent, 1-(iminodiacetic acid di-tert-butylester)-3-glycidoxy-propyltrimethoxysilane (IDA-silane). Various modified silicas of different ligand densities have been prepared by using mixtures between 1 and 100% of the IDA-silane diluted with the corresponding 3-glycidoxy-propyltrimethoxysilane (GLYMO-silane). Frontal analysis was used with the IDA-Cu(II)-Concanavalin-A and IDA-Cu(II)-lysozyme systems to evaluate the capacity and the association constants for these HPIMAC sorbents. With these metal chelate sorbents the specific binding capacity per unit area increased continuously with the ligand density for the nonporous sorbents but reached a maximum at about 50% of the maximum ligand coverage for the porous sorbents. The association constant for the chelate-protein complex was highest for both concanavalin-A (Con-A) and lysozyme (HEWL) at the highest ligand density and decreased with lower ligand density. These observations have been evaluated in terms of the accessibility of histidine residues on the surface of the two test proteins and their ability to act as binding sites for the copper ions in the coordination complex. The experimental data indicate that both steric and conformational effects result in multiple classes of binding phenomena with Con-A and HEWL at high ligand concentrations. These experimental results provide a useful guideline for the design of silica-based sorbents for application in the HPIMAC of proteins.
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PMID:Influence of ligand density on the properties of metal-chelate affinity supports. 838 18

The use of molecular genetics to introduce both a metal ion binding site and a nitroxide spin label into the same protein opens the use of paramagnetic metalnitroxyl interactions to estimate intramolecular distances in a wide variety of proteins. In this report, a His-Xaa3-His metal ion binding motif was introduced at the N terminus of the long interdomain helix of T4 lysozyme (Lys-65 --> His/Gln-69 --> His) of three mutants, each containing a single nitroxide-labeled cysteine residue at position 71, 76, or 80. The results show that Cu(II)-induced relaxation effects on the nitroxide can be quantitatively analyzed in terms of interspin distance in the range of 10-25 A using Redfield theory, as first suggested by Leigh [Leigh, J.S. (1970) J. Chem. Phys. 52, 2608-2612]. Of particular interest is the observation that distances can be determined both under rigid lattice conditions in frozen solution and in the presence of motion of the spins at room temperature under physiological conditions. The method should be particularly attractive for investigating structure in membrane proteins that are difficult to crystallize. In the accompanying paper, the technique is applied to a polytopic membrane protein, lactose permease.
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PMID:A method for distance determination in proteins using a designed metal ion binding site and site-directed spin labeling: evaluation with T4 lysozyme. 861 88

As shown in the accompanying paper, the magnetic dipolar interaction between site-directed metal-nitroxide pairs can be exploited to measure distances in T4 lysozyme, a protein of known structure. To evaluate this potentially powerful method for general use, particularly with membrane proteins that are difficult to crystallize, both a paramagnetic metal ion binding site and a nitroxide side chain were introduced at selected positions in the lactose permease of Escherichia coli, a paradigm for polytopic membrane proteins. Thus, three individual cysteine residues were introduced into putative helix IV of a lactose permease mutant devoid of native cysteine residues containing a high-affinity divalent metal ion binding site in the form of six contiguous histidine residues in the periplasmic loop between helices III and IV. In addition, the construct contained a biotin acceptor domain in the middle cytoplasmic loop to facilitate purification. After purification and spin labeling, electron paramagnetic resonance spectra were obtained with the purified proteins in the absence and presence of Cu(II). The results demonstrate that positions 103, 111, and 121 are 8, 14, and > 23 A from the metal binding site. These data are consistent with an alpha-helical conformation of transmembrane domain IV of the permease. Application of the technique to determine helix packing in lactose permease is discussed.
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PMID:Distance determination in proteins using designed metal ion binding sites and site-directed spin labeling: application to the lactose permease of Escherichia coli. 861 89


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