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)

Thermolysis of 2,2'-azo-bis-(2-amidinopropane) under air in the presence of lysozyme leads to extensive inactivation of the enzyme. The number of inactivated enzyme molecules per radical produced increases with the enzyme concentration up to values considerably larger than one. Enzyme inactivation is accompanied by extensive tryptophan modification. Over the enzyme concentration range considered (1.7 to 130 microM) nearly 4 tryptophan groups are modified per enzyme molecule inactivated. Both the inactivation and tryptophan modification are prevented by micromolar concentrations of propyl gallate. The results are interpreted in terms of an efficient inactivation of the enzyme by the alkylperoxyl radicals generated by thermolysis of the azocompound.
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PMID:Inactivation of lysozyme by alkylperoxyl radicals. 239 21

The interaction of monoclonal anti-peptide antibodies with the free peptide and its protein counterpart has been evaluated for hen egg white lysozyme and the peptide constituting residues 38 to 45. Fluorescence methodology has been developed for the measurement of association constants based on resonance energy transfer between the excited tryptophan of antibody and bound peptide ligand conjugated to a fluorescent probe. Five antibodies, four IgM and one IgG, have been assayed by ELISA, and have demonstrated binding to the adsorbed peptide alone, to the adsorbed lysozyme alone, or to both. Multivalent interaction with the adsorbed ligand is a key factor in the efficacy of binding. Measurement of binding constants in homogeneous solution, by equilibrium dialysis and energy transfer, demonstrated that lysozyme was bound to an IgG antipeptide antibody with an association constant (4 X 10(2) M-1) 200-fold less than that for the free peptide (8 X 10(4) M-1). It was also inferred for IgM that an association constant of the order of 10(2) M-1 was sufficient to effect selective interaction in a system providing multivalent interaction. The shared conformations between protein and peptide, implied by the specific reactivity of the anti-peptide antibody with the protein, points to structural fluctuations of the surface regions and residues of globular proteins.
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PMID:Interaction of monoclonal anti-peptide antibodies with lysozyme. 258 21

The stopped-flow chemical modification with N-bromosuccinimide (NBS) of Trp 62 of hen (chicken) egg white lysozyme (EC 3.2.1.17) was found to depend greatly on pH: it was not observed at pH's above 7, but it was observed at pH's lower than 6. In addition, at pH's between 6 and 7 the NBS modification showed a delta epsilon pH profile similar to a "titration curve," giving a pK (congruent to 6.5) nearly equal to the pK (congruent to 6.2) of a catalytic residue, Glu 35. The stopped-flow chemical (NBS) modification of N-acetyl-L-tryptophan ethyl ester, a model compound of Trp 62, does not depend on pH at the pH's examined, approximately 3.5-8.5. These experimental results suggest that a change in the state of Trp 62 at Subsite C is induced by protonation-deprotonation of an ionizable residue, which could be Glu 35 (catalytic site), indicating that stopped-flow NBS modification is a good probe for detection of changes in the micorenvironment around the tryptophan residue(s) of enzymes.
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PMID:Stopped-flow chemical modification with N-bromosuccinimide: a good probe for changes in the microenvironment of the Trp 62 residue of chicken egg white lysozyme. 273 67

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

The crystal structure of the complex of the anti-lysozyme HyHEL-10 Fab and hen egg white lysozyme has been determined to a nominal resolution of 3.0 A. The antigenic determinant (epitope) on the lysozyme is discontinuous, consisting of residues from four different regions of the linear sequence. It consists of the exposed residues of an alpha-helix together with surrounding amino acids. The epitope crosses the active-site cleft and includes a tryptophan located within this cleft. The combining site of the antibody is mostly flat with a protuberance made up of two tyrosines that penetrate the cleft. All six complementarity-determining regions of the Fab contribute at least one residue to the binding; one residue from the framework is also in contact with the lysozyme. The contacting residues on the antibody contain a disproportionate number of aromatic side chains. The antibody-antigen contact mainly involves hydrogen bonds and van der Waals interactions; there is one ion-pair interaction but it is weak.
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PMID:Structure of an antibody-antigen complex: crystal structure of the HyHEL-10 Fab-lysozyme complex. 276 5

Phosphorescence spectroscopy on mouse myeloma IgA J539 in rigid solution at 77K revealed the type of anomalous short-lived component in the tryptophan decay originally observed with lysozyme (Churchich, J.E., 1966. Biochim. Biophys. Acta. 120:406-412) and seen in a large number of Bence Jones proteins (Longworth, J.W., C.L. McLaughlin, and A. Solomon. 1976. Biochemistry. 15:2953-2958). The decay time of the anomalous component that results from the interaction between tryptophan side chains and disulfide linkages in proteins was observed to significantly lengthen in J539 in response to binding of a galactan antigen. With hen egg-white lysozyme in which the type of fluorescence enhancement on ligand binding seen with J539 has also been observed, phosphorescence measurements revealed a similar lengthening of the decay time of the disulfide-induced anomalous component in the tryptophan decay. These perturbations are interpreted as ligand-induced changes to the tryptophan-disulfide proximities that have been shown to exist in these structures. Given the short-range nature of the disulfide perturbation (see following article) the observations suggest, in particular when combined with x-ray crystallographic data, that phosphorescence decay-time measurements of disulfide perturbations can serve as a sensitive spectroscopic indicator of subtle conformational changes in immunoglobulins and other tryptophan-disulfide containing proteins.
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PMID:Evidence for ligand-induced conformational changes in proteins from phosphorescence spectroscopy. 277 30

Intramolecular electron transfer in hen egg-white lysozyme between tryptophan and tyrosine units was investigated by means of pulse radiolysis in the temperature range 288-333 K. An Arrhenius plot for the kinetics of this process shows a sharp break at approximately 303 K (30 degrees C) compatible with the trend noted earlier (cf P. Jolles, et al. BBA, 491, 354, (1977)) on the Arrhenius plot for kinetics of bacterial substrate digestion by lysozyme. The departure from linearity of the Arrhenius plot for intramolecular electron transfer is interpreted in terms of local intralobe fluctuations of the native structure of lysozyme. It is suggested that such an approach can be useful for probing predenaturational changes in proteins.
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PMID:Temperature dependence of intramolecular electron transfer as a probe for predenaturational changes in lysozyme. 280 49

The pH dependence of the exchange rates for a number of tryptophan and amide hydrogen atoms in hen egg-white lysozyme has been determined at temperatures well below the thermal denaturation temperature. The pH behaviour of each hydrogen is unique and can differ markedly from that of simple compounds. A model for electrostatic effects in proteins is described and used to explain a number of the features of the pH dependence of the exchange rates of certain hydrogens. The results indicate that exchange takes place from a conformation of the protein closely similar to that of the native protein, with local fluctuations providing the mechanism for exchange. For the more-buried hydrogens at low pH values there is a general increase in the exchange rates caused by the decreasing stability of the protein as calculated from the electrostatic model. The analysis shows how evidence from hydrogen exchange studies can be used to provide information about electrostatic interactions in localized regions of proteins. A description of the electrostatic model and some applications are given in the Appendix.
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PMID:Electrostatic effects and hydrogen exchange behaviour in proteins. The pH dependence of exchange rates in lysozyme. 282 93

From acrylamide quenching results, analyzed by an itterative non-linear least-squares method, we have shown that the fluorescence of multitryptophan-containing proteins, such as horse-liver alcohol dehydrogenase, 3-phosphoglycerate kinase and lysozyme, can be resolved for different segmental contributions, each characterized by collisional (Ki) and static (Vi) quenching constants. The ability to resolve the heterogeneous fluorescence of proteins makes it possible to follow changes in dynamics of the individual residues. In yeast 3-phosphoglycerate kinase, which contains only two tryptophan residues, three fluorescent fractions, characterized by different accessibility to the quencher, were observed. Two of them are assigned to one of the tryptophan residue. This may be interpreted in terms of conformational fluctuations, which facilitate the access of acrylamide molecules to the buried tryptophan residues.
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PMID:The resolution of heterogeneous fluorescence of multitryptophan-containing proteins studied by a fluorescence-quenching method. 294 4

Lysozyme was reacted with xylose, methyl linoleate, glyoxal, methylglyoxal and diacetyl in an aqueous system (50 degrees C, pH 6.0), and browning, polymerization, changes of amino acids composition and relative digestibility of the browned lysozyme were investigated. Browning intensity as well as degree of polymerization of lysozyme in the reaction with alpha-dicarbonyls was higher than with xylose or methyl linoleate. After 10 days of reaction with alpha-dicarbonyls, the amino acid composition of lysozyme was markedly affected; i.e., 30-70% of lysine, 40-50% of tryptophan and 90% of arginine were lost respectively. By digestion with a pepsin-pancreatin system, it was observed that the relative digestibility of lysozyme reacted with dicarbonyl was lower than that of lysozyme reacted with methyl linoleate or xylose.
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PMID:Changes of amino acids composition and relative digestibility of lysozyme in the reaction with alpha-dicarbonyl compounds in aqueous system. 308 26


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