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)

Single-crystal neutron diffraction has been used to observe the interactions between deuterated ethanol (CD3CD2OH) and lysozyme in triclinic crystals of hen egg white lysozyme soaked in 25% (v/v) ethanol solutions. A total of 6047 observed reflections to a resolution of 2 A were used, and 13 possible ethanol sites were identified. The three highest occupied sites are close to locations for bromoethanol found in an earlier study by Yonath et al. [Yonath, A., Podjarny, A., Honig, B., Traub, W., Sielecki, A., Herzberg, O., & Moult, J. (1978) Biophys. Struct. Mech. 4, 27-36]. Structure refinements including a model for the flat solvent lead to a final crystallographic agreement factor of 0.097. Comparison with earlier neutron studies on triclinic lysozyme showed that neither the molecular structure nor the thermal motions were affected significantly by the ethanol. A detailed analysis of the ethanol-lysozyme contacts showed 61% of these to be with hydrophobic sites, in agreement with the dominant hydrophobic nature of ethanol. This, together with the fact that the molecular structure of lysozyme is not perturbed, suggests a model for denaturation of lysozyme by alcohol, which proceeds via a dehydration of the protein at high alcohol concentration.
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PMID:Study of ethanol-lysozyme interactions using neutron diffraction. 408 97

[methyl-(14)C]Methionine and S-adenosyl[methyl-(14)C]methionine were incorporated into the methoxycarotenoids spheroidene and spheroidenone by Rhodopseudomonas spheroides. The incorporation was greatly enhanced in the presence of lysozyme. On degradation of labelled spheroidene by hydriodic acid, the (14)C label was recovered in methyl iodide. Degradation of spheroidenone by reduction and allylic dehydration and demethylation of the reduction product gave a mixture of unlabelled carotenoid hydrocarbons, including 3,4-didehydrolycopene and 3,4-didehydro-7',8'-dihydrolycopene. The label from [methyl-(14)C]methionine and S-adenosyl[methyl-(14)C]methionine was located specifically in the methoxy group of spheroidene and spheroidenone. The biosynthesis of methoxycarotenoids in Rps. spheroides involves methylation of the tertiary hydroxyl groups of intermediates with S-adenosylmethionine.
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PMID:Carotenoid biosynthesis in Rhodopseudomonas spheroides. S-adenosylmethionine as the methylating agent in the biosynthesis of spheroidene and spheroidenone. 454 66

Upon the removal of water, proteins undergo a major, reversible rearrangement of their secondary structure, as revealed by FTIR spectroscopy. We have found herein that for recombinant human albumin (rHA) the extent of this structural change does not depend significantly either on the composition of the aqueous solution prior to lyophilization (protein concentration, pH, and the presence of excipients such as dextran or NaCl) or on the mode of dehydration (lyophilization, spray drying, or rotary evaporation), even though these factors profoundly affect rHA's solid-state stability against moisture-induced aggregation. In all cases, the alpha-helix content of rHA drops from 58% in solution to 25-35% in the dehydrated state, the beta-sheet content rises from 0 to 10-20%, and unordered structures increase from 40% to 50-60%. We have also investigated another model protein, hen egg-white lysozyme, and confirmed that it too undergoes a significant alteration of the secondary structure upon lyophilization. The extent of this structural reorganization has been found to be insensitive to the pH of the aqueous solution prior to lyophilization from pH 1.9 to 5.1, even though the thermal transition temperature (Tm) in aqueous solution over this range varies by 30 degrees C.
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PMID:Fourier-transform infrared spectroscopic investigation of protein stability in the lyophilized form. 749 2

Fourier transform infrared spectroscopy has been used to compare the structure of a range of proteins in solution and in the form of single crystals. An infrared microscope was used to record the spectra of single crystals of the proteins. The proteins studied in this way were hen egg white lysozyme, bovine pancreatic ribonuclease A, bovine gamma-II crystallin, human serum amyloid P component, Endothia parasitica pepsin and Mucor pusillus pepsin. The amide I and amide II bands in the FTIR spectra of these proteins were analysed using derivative procedures thereby providing information on the secondary structure. The crystals were held under a vapour of mother liquor to reduce the effects of dehydration. A comparison of the spectra revealed that spectra recorded from crystals of lysozyme, ribonuclease A and gamma-II crystallin are nearly identical to those recorded from the proteins in solution. However, differences are observed between the spectra of serum amyloid P component, Endothia parasitica pepsin and Mucor pusillus pepsin in solution compared with that of the crystalline form These differences are suggested to be due to rearrangements of turn structures within the protein structure.
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PMID:A comparison of infrared spectra of proteins in solution and crystalline forms. 774 92

Temperature dependencies of 1H non-selective NMR T1 and T2 relaxation times measured at two resonance frequencies and natural abundance 13C NMR relaxation times T1 and T1r measured at room temperature have been studied in a set of dry and wet solid proteins - Bacterial RNase, lysozyme and Bovine serum albumin (BSA). The proton and carbon data were interpreted in terms of a model supposing three kinds of internal motions in a protein. These are rotation of the methyl protons around the axis of symmetry of the methyl group, and fast and slow oscillations of all atoms. The correlation times of these motions in solid state are found around 10(-11), 10(-9) and 10(-6)s, respectively. All kinds of motion are characterized by the inhomogeneous distribution of the correlation times. The protein dehydration affects only the slow internal motion. The amplitude of the slow motion obtained from the carbon data is substantially less than that obtained from the proton data. This difference can be explained by taking into account different relative inter- and intra- chemical group contributions to the proton and carbon second moments. The comparison of the solid state and solution proton relaxation data showed that the internal protein dynamics in these states is different: the slow motion seems to be few orders of magnitude faster in solution.
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PMID:Dynamic structure of proteins in solid state. 1H and 13C NMR relaxation study. 891 57

Bacterial endospores derive much of their longevity and resistance properties from the relative dehydration of their protoplasts. The spore cortex, a peptidoglycan structure surrounding the protoplasm, maintains, and is postulated to have a role in attaining, protoplast dehydration. A structural modification unique to the spore cortex is the removal of all or part of the peptide side chains from the majority of the muramic acid residues and the conversion of 50% of the muramic acid to muramic lactam. A mutation in the cwlD gene of Bacillus subtilis, predicted to encode a muramoyl-L-alanine amidase, results in the production of spores containing no muramic lactam. These spores have normally dehydrated protoplasts but are unable to complete the germination/ outgrowth process to produce viable cells. Addition of germinants resulted in the triggering of germination with loss of spore refractility and the release of dipicolinic acid but no degradation of cortex peptidoglycan. Germination in the presence of lysozyme allowed the cwlD spores to produce viable cells and showed that they have normal heat resistance properties. These results (i) suggest that a mechanical activity of the cortex peptidoglycan is not required for the generation of protoplast dehydration but rather that it simply serves as a static structure to maintain dehydration, (ii) demonstrate that degradation of cortex peptidoglycan is not required for spore solute release or partial spore core rehydration during germination, (iii) indicate that muramic lactam is a major specificity determinant of germination lytic enzymes, and (iv) suggest the mechanism by which the spore cortex is degraded during germination while the germ cell wall is left intact.
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PMID:Muramic lactam in peptidoglycan of Bacillus subtilis spores is required for spore outgrowth but not for spore dehydration or heat resistance. 898 24

Earlier studies involving water-mediated transformations in lysozyme and ribonuclease A have shown that the overall movements in the protein molecule consequent to the reduction in the amount of surrounding water are similar to those that occur during enzyme action, thus highlighting the relationship among hydration, plasticity, and action of these enzymes. Monoclinic lysozyme retains its crystallinity even when the level of hydration is reduced further below that necessary for activity (about 0.2 gram of water per gram of protein). In order to gain insights into the role of water in the stability and the plasticity of the protein molecule and the geometrical basis for the loss of activity that accompanies dehydration, the crystal structures of monoclinic lysozyme with solvent contents of 17.6%, 16.9%, and 9.4% were determined and refined. A detailed comparison of these forms with the normally hydrated forms show that the C-terminal segment (residues 88-129) of domain I and the main loop (residues 65-73) in domain II exhibit large deviations in atomic positions when the solvent content is reduced, although the three-dimensional structure is essentially preserved. Many crucial water bridges between different regions of the molecule are conserved in spite of differences in detail, even when the level of hydration is reduced well below that required for activity. The loss of activity that accompany dehydration appears to be caused by the removal of functionally important water molecules from the active-site region and the reduction in the size of the substrate binding cleft.
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PMID:Role of water in plasticity, stability, and action of proteins: the crystal structures of lysozyme at very low levels of hydration. 971 62

The nature of the interaction responsible for the inhibition of protein unfolding and subsequent damage by sugars during dehydration is unclear. The relationship between sample moisture content measured by coulometric Karl Fischer titration and the apparent moisture content predicted by the area of the protein side chain carboxylate band at approximately 1580 cm-1 in infrared spectra of dried protein-sugar samples was examined. For samples in which a high level of native protein structure was retained in the dried solid, the apparent moisture content predicted by the carboxylate band area was greater than the actual moisture content, indicating that protection results from direct sugar-protein hydrogen bonding and not entrapment of water at the protein surface. Further, we show that the degree of structural protection conferred by sucrose and trehalose apparent in second derivative, amide I infrared spectra, correlates with the extent of hydrogen bonding between sugar and protein. The failure of dextran to inhibit dehydration-induced lysozyme unfolding is shown to result from the inability of the polymer to hydrogen bond adequately to the protein. Therefore, formation of an amorphous phase alone is not sufficient to maintain protein structure during dehydration. Glucose hydrogen bonds to a high degree with dried lysozyme, but is incapable of inhibiting lyophilization-induced protein unfolding in the absence of an effective cryoprotectant. However, the addition of polyethylene glycol, which is known to protect proteins during freezing, but not drying, to glucose protected lysozyme structure during lyophilization. Together, these results show that hydrogen bonding between carbohydrate and protein is necessary to prevent dehydration-induced protein damage. However, hydrogen bonding alone is not sufficient to protect proteins during lyophilization in the absence of adequate freezing protection.
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PMID:Hydrogen bonding between sugar and protein is responsible for inhibition of dehydration-induced protein unfolding. 1032 24

This study extends previous research on the interaction of biomaterials with immobilized Cu(II) by isothermal titration calorimetry (ITC) on Fe(III). The difference of the binding behavior of protein with that of the immobilized metal ions is also discussed. For the immobilized Fe(III), ITC results show that the adsorption enthalpy at a constant pH value decreased as the NaCl concentration increased and also decreased with the pH values at constant NaCl concentrations. The adsorption enthalpy become negative under higher pH values or higher salt concentrations indicating the adsorption process is partly driven by the enthalpy. The enthalpy of lysozyme with Fe(III) is higher than that with Cu(II) implying that the heat required for the dehydration of Cu(II) is lower than for the dehydration of Fe(III) and/or that the heat generated from the formation of the coordination with Cu(II) is higher than with Fe(III). In addition, the comparison of different immobilized metal ions corresponding to the equilibrium binding affinity suggests that the binding force of lysozyme with Cu(II) is higher than with Fe(III). This study presents the chemical differences between the binding affinity and the adsorption enthalpy of lysozyme interacting with the immobilized metal ions. The binding and thermodynamic data presented in this study elucidate the mechanism and process of lysozyme binding with immobilized metal ions. In addition, the thermodynamic characteristic functions provide valuable information enabling a more thorough understanding of protein adsorption at the immobilized metal ion affinity surface. Copyright 1999 Academic Press.
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PMID:Microcalorimetric Studies of the Interactions of Lysozyme with Immobilized Metal Ions: Effects of Ion, pH Value, and Salt Concentration. 1033 77

The early stage products of the Maillard reaction of egg white lysozyme with D-glucose were studied. Incubation with D-glucose at 50 degrees C for 20 days caused reaction on the Lys and Arg residues of lysozyme as follows: all of the six Lys residues and 10 of the 11 Arg residues in lysozyme reacted with D-glucose; Arg 61 did not react with D-glucose. The Lys residues reacted with D-glucose with 1 mol of dehydration per mole of residue, and the Arg residues reacted with 2 mol of dehydration per mole of residue. The major constituent of the Amadori product with the epsilon-amino group of the Lys residue and the D-glucose was found to be the beta-pyranose form. The structure of the early stage product of the Maillard reaction of a protein with a sugar is the same as that of an amino acid with a sugar.
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PMID:Structural studies of the Maillard reaction products of a protein using ion trap mass spectrometry. 1067 72


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