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)

Incorporation of 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2), the principal mutagen in a tryptophan pyrolysate, into bovine serum albumin was catalyzed by myeloperoxidase. Hydrogen peroxide was essential for the incorporation reaction and albumin was required for optimal incorporation of Trp-P-2 into protein. Other various proteins, such as histone, lysozyme, cytochrome c, and gamma-globulin could also incorporate Trp-P-2, but poly(L-Arg), poly(L-Lys), and poly(L-Glu) could not. The incorporation of Trp-P-2 into albumin was inhibited by L-tyrosine and L-tryptophan, but not by other amino acids. Trp-P-2 incorporated into albumin was not released from the protein by treatment with 0.3 N HCl, or 0.3 N NaOH for 2 h at 35 degrees C, or with 1% sodium dodecylsulfate for 2.5 min at 100 degrees C. On electrophoresis on polyacrylamide containing sodium dodecylsulfate or urea and on chromatography on Sepharose CL-6B in 6 M guanidine/HCl, Trp-P-2 incorporated into albumin or lysozyme migrated with these proteins. These findings indicate that Trp-P-2 is covalently bound to these acceptor proteins.
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PMID:Myeloperoxidase-catalyzed binding of 3-amino-1-methyl-5H-pyrido[4,3-b]indole, a tryptophan pyrolysis product, to protein. 625 79

Equilibrium and kinetic studies of the unfolding-refolding of phage T4 lysozyme induced by guanidine hydrochloride are reported. Tryptophan fluorescence and circular dichroism (CD) were used as observables. Several results indicated the existence of intermediates in the unfolded-folded transition, including (1) the noncoincidence of the transition observed by fluorescence and CD, (2) the asymmetry of the transition recorded by CD, and (3) triphasic kinetics, followed by both observables, accounting for the forward and reverse processes. Our data were inconsistent with an independent unfolding or refolding of each domain. They indicated the existence of residual structured regions particularly resistant to denaturant, which involved one or more of the three tryptophans located in the C-terminal domain. Kinetic analysis has made it possible to propose a minimum pathway corresponding to a sequential refolding, with dead-end species arising from an intermediate. We compared our data with the experimental results of Elwell and Schellman [Elwell, M., & Schellman, J.A. (1975) Biochim. Biophys. Acta 386, 309-313] and the theoretical analysis of B. Maigret (unpublished results) and proposed that the C-terminal domain refolds first, after which the overall structure can be formed and stabilized.
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PMID:Evidence for intermediates during unfolding and refolding of a two-domain protein, phage T4 lysozyme: equilibrium and kinetic studies. 636 23

Protein A (PA)-activity was detected in Staphylococcus aureus strain Wood 46 which had been considered to be PA-negative. This staphylococcal strain bound 28% of 125I-labelled IgG, compared with 89% by strain Cowan I. The binding activities of both S. aureus strains were saturable, time-dependent and specific. The dissociation constants of 1.6 X 10(-9) M for Wood 46 and 9.3 X 10(-8) M for Cowan I indicated a similar affinity for human IgG in both strains. The number of IgG-binding sites were estimated to be 16,970 for Wood 46 and 41,200 for Cowan I. Exposure to heat and ultrasonication reduced PA-activities of strain Cowan I, but not that of strain Wood 46. Extraction of the staphylococci with guanidine and formic acid resulted in a reduction of IgG-binding activities only in strain Wood 46. Photooxidation, trypsinization and lysozyme treatment also diminished IgG-binding of strain Wood 46 to a larger extent than that of strain Cowan I. Extracellular PA from S. aureus strains Wood 46 and Cowan I could be purified by affinity chromatography on IgG-sepharose. The purified PA preparations gave single protein bands upon SDS-polyacrylamide gel electrophoresis. Their molecular weights were 42,000 and their isoelectric points approximated 5.0.
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PMID:Characterization of immunoglobulin G binding to Staphylococcus aureus strain Wood 46. 653 38

Using strains of Streptococcus mutans suspended in human saliva, the salivary proteins capable of binding to the surface of the bacteria were identified by immunological and electrophoretic techniques. Six binding components were recognized: IgA, lysozyme, some high molecular weight material (greater than 400,000), probably a glycoprotein, a low molecular weight component (11-13,000), a 150,000 mol. wt protein, and one major component, mol. wt 20-25,000 which did not resolve fully on SDS-polyacrylamide electrophoresis. All these salivary components could be desorbed from the bacteria with 1 M NaCl, and subsequent extraction of the same cells with 6 M guanidine-HCl did not release any more salivary material. The significance of the binding of these salivary components is unknown but some may modify the behaviour of the organisms in vivo.
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PMID:The adsorption of human salivary components to strains of the bacterium Streptococcus mutans. 659 86

Membrane vesicles from lysed suspensions of turkey-grown Pasteurella multocida were treated with various solubilizing agents to release protein that may contain cross-protection factor. Potassium thiocyanate, NaOH-glycine, lithium diiodosalicylate, guanidine hydrochloride, n-butanol, dimethyl sulfoxide, Triton X-100, and sodium lauryl sarcosinate were each tested as solubilizing agents. Vaccines made from combining solubilized membrane vesicles with complete lysate supernatant fluid produced various degrees of protection against challenge exposure with a heterologous serotype of P multocida in turkeys. Only vaccines prepared from membranes that were solubilized with potassium thiocyanate and sodium lauryl sarcosinate protected as well as complete lysate from turkey-grown P multocida. The amount of protein in each vaccine did not relate to protection. Distinct chemical differences were observed between lysates prepared from turkey-grown P multocida and lysates prepared from 41 C broth-grown P multocida. The external morphology of P multocida, after treatment with lysozyme and EDTA, was similar whether grown in broth or in turkeys.
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PMID:Lysates of turkey-grown Pasteurella multocida: effects of solubilizing agents on the immunologic properties of membrane vesicles. 683 37

The thermal denaturation of lysozyme in aqueous sulfoxide solutions (pH 3) was investigated by differential scanning calorimetry (DSC). The sulfoxides employed were dimethylsulfoxide (DMSO), ethylmethylsulfoxide, (DMSO), dimethylsulfoxide (DMSO), and butylmethylsulfoxide (BMSO). The temperature of denaturation, Td, decreased with an increase in the concentration of sulfoxide, the decrease becoming much more pronounced at higher sulfoxide concentrations. The lowering of Td was enhanced by an increase in the hydrocarbon content of the sulfoxide molecule. The enthalpy of denaturation, delta Hd, showed a complex dependence on the solvent composition; the delta Hd first increased with increasing sulfoxide concentration and then started decreasing at different concentrations for each sulfoxide. This behavior is analogous to that with monohydric alcohols, but is different from that with guanidine hydrochloride. These results may be interpreted in terms of the interactions of the sulfoxide added with the protein and with water.
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PMID:Effect of dimethylsulfoxide and its homologues on the thermal denaturation of lysozyme as measured by differential scanning calorimetry. 711 80

The denaturation of ribonuclease A, lysozyme alpha-lactalbumin, and myoglobin by urea, guanidine hydrochloride, and guanidine thiocyanate has been followed with the use of difference spectral measurements. The free energy of stabilization (delta GH2OD) has been determined by the linear extrapolation of the free energy of denaturation to zero denaturant concentration. The values of delta GH2OD are 7.3 +/- 0.2, 8.9 +/- 0.1, 4.3 +/- 0.1;, and 7.9 +/- 0.2 kcal/mol at 25 degrees C for ribonuclease A (pH 7.0), lysozyme (pH 7.0), alpha-lactalbumin (pH 7.0), and myoglobin (pH 6.6), respectively. The dependence of the free energy of denaturation on concentration ranges from 0.88 to 2.08 kcal/mol.M for urea and from 1.27 to 4.22 kcal/mol.M for guanidine hydrochloride for four proteins. The ratio of this dependence in guanidine hydrochloride to that in urea may depend on the polarity of the amino acid residues in the unfolding unit.
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PMID:Estimation of the free energy of stabilization of ribonuclease A, lysozyme, alpha-lactalbumin, and myoglobin. 713 Jan 87

The enthalpies of transfer of hen egg white lysozyme from water to aqueous solutions of 1-propanol were determined by isothermal flow calorimetry at 10, 17, 25, and 40 degrees C in 0.04 M, pH 2 glycine buffer. Alcohol concentrations up to 3.4 M were employed. Four regions in the dependence of the enthalpy of transfer on alcohol concentration can be discerned: a region of linear increase observable at 10, 17, and 25 degrees C, an inflection region observed at 17 and 25 degrees C, a second linear region observable at 17, 25, and 40 degrees C, and a region of decreasing enthalpies seen at 40 degree C. Combination of differential scanning calorimetric data on lysozyme in PrOH-H2O mixtures [Velicelebi, G., & Sturtevant, J. M. (1979) Biochemistry 18, 1180-1186] with the transfer enthalpies reported here shows that the enthalpy in the system can be regarded as a state function and that the apparent specific heat is at first slightly decreased and then strongly increased by the addition of 1-propanol. Comparison of the results of the interaction with guanidine hydrochloride [Pfeil, W., & Privalov, P. L. (1976) Biophys. Chem. 4, 23-50] indicates that the denaturing effects of these two reagents involve very different mechanisms.
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PMID:Calorimetric study of the interaction of lysozyme with aqueous 1-propanol. 724 70

Thermodynamic investigations of alpha-lactalbumin have been performed by isothermal calorimetric guanidine hydrochloride titrations as well as by scanning calorimetric measurements in the presence and absence of guanidine hydrochloride. Compared with lysozyme, alpha-lactalbumin is less stable, and its changes of enthalpy and heat capacity at unfolding are lower. Thermal unfolding of alpha lactalbumin can be described to the first approximation by the two-state transition model even in the presence of guanidine hydrochloride.
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PMID:Thermodynamics of alpha-lactalbumin unfolding. 726 Mar 34

Previous studies of the reversible unfolding of alpha-lactalbumin in the acid to neutral pH region have shown that the unfolding transition with guanidine hydrochloride involves a stable intermediate which is similar to a partially unfolded state produced by acid transition. In order to clarify how the interaction of ionizable groups takes part in stabilization of the native structure during the folding of the protein, the transitions were further investigated in the alkaline region in the presence of the denaturant by means of circular dichroism, difference spectra and pH-jump measurements, and the effects of pH on the equilibrium and kinetics of the unfolding in the whole pH region are discussed. The alkaline state is indistinguishable from the acid state in equilibrium and kinetic properties. Thus, as a first approximation, the total unfolding in the whole pH region can be expressed as a three-state mechanism involving the native (N), the intermediate (A), and the fully unfolded (D) states. The strong pH dependence of the N Equilibrium A transition above pH 10 is almost entirely ascribable to the abnormal tyrosines in the N state previously detected by the pH-jump titration method, while the dependence between pH 7 and 10 also suggests the presence of an abnormal alpha-amino group. The normalization of most of the alkaline and the acidic abnormally ionizable groups in the N state occurs simultaneously in the first step of the unfolding pathway, i.e., the forward activation of the N Equilibrium A transition, and the final step of the folding may be associated with the interaction of the ionizable groups. Among the abnormally ionizable groups detected, the tyrosyl and carboxyl groups are most important in view of the large changes in their pK values, suggesting the presence of some interactions, even if only indirect, between these groups. Alignment data of amino acid residues also suggest that at least one such abnormal tyrosyl residue (Tyr 50) and its neighbors are conserved throughout in the alpha-lactalbumin-lysozyme group of proteins. Possible mechanisms of the interaction between the tyrosyl and carboxyl groups are discussed.
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PMID:Role of the interaction between ionizable groups in the folding of bovine alpha-lactalbumin. 728 38


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