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)

Autoxidized LA is classified into four groups, LA, LAHPO, SP and FP. Lysozyme is inactivated by these products in the increasing order as follows: FP less than LA less than LAHPO less than SP. The effects of these products on the amino acid composition of lysozyme is examined. All kinds of amino acid residues were not damaged until lysozyme was incubated with LA and LAHPO at 45 degrees C for 100 days. The susceptible amino acid residues attacked by the autoxidized products are tryptophan, lysine and histidine. The specific loss of methionine by SP occurs during acid-hydrolysis. The effect of SP was the strongest among the autoxidized products. FP was almost noneffective. The destructive actions of BP, MA and PA were compared with those of autoxidized products. Effects of these compounds did not resemble those of autoxidized products. It was concluded that tryptophan, lysine and histidine residues were specifically attacked by SP.
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PMID:Lysozyme damage caused by secondary degradation products during the autoxidation process of linoleic acid. 0 40

Methylene blue immobilized on porous glass beads was used to catalyze the photooxidation of methionine alone and the methionine residues of lysozyme. A solution of 2 mM methionine in 50% acetic acid was oxidized to methionine sulfoxide in the presence of immobilized methylene blue after 6 h of photooxidation at 37 degrees C. Selective photooxidation of the methionyl residues in lysozyme was achieved after 26 h of reaction in 84% acetic acid at 4 degrees C. The specific activity of lysozyme exposed to light in the presence of methylene blue decreased by 94%, while that of a lysozyme solution in the presence of methylene blue not exposed to light decreased by 21%. The lysozyme solution exposed to light but not containing the methylene blue beads lost 33% of its specific activity after the same period of photooxidation. It was shown that the decrease in enzyme activity was not caused by adsorption of the enzyme onto the beads.
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PMID:Photooxidation of methionine with immobilized methylene blue as photooxidizer. 0 34

The chemical modification of lysozyme (I) has been accomplished with alpha, alpha'-dibromo-p-xylenesulfonic acid (DBX) at five different pH values. I was alkylated by DBX at room temperature (28 degrees C) with decrease in enzyme activity. The rate of inactivation depended upon the pH at which alkylation was carried out. The highest rate was seen at alkaline pH values; the lowest at more acidic pH values. Amino acid analyses showed that-two lysines and two tryptophan residues had been modified at pH 9; two lysines, one tryptophan and one methionine had reacted at pH 8. A histidine residue was bound at pH 6.5 together with a tryptophan residue. At the lower pH values (2.7, 4.5, 6.5), alkylation occurred with a single tryptophan residue each. Fluorescence and CD data both ruled out the participation of tryptophans 62 or 108. Labeling experiments showed that two residues of DBX-35S were bound per molecule of I at both pH9 and pH8; one residue of DBX was bound per molecule of I at the other pH values. Sedimentation coefficients were characteristic of native lysozyme. The stoichiometry of binding and residue modification indicated that intra-molecular cross links were established. The pH dependence of the cross-linking provides means to measure several allowed intra-molecular distances. The results presented here are consistent with the existence of side chain motion in lysozyme.
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PMID:The pH dependence of binding of alpha,alpha'-dibromo-p-xylenesulfonic acid to lysozyme. 0 99

This paper demonstrates the existence of regions in eight small globular proteins in which the side chains of sulfur-containing amino acids (cysteine and methionine) alternate in space with side chains of aromatic amino acids (histidine, phenylalanine, tryptophan and tyrosine). The proteins are: rubredoxin, high potential iron protein, cytochrome c, flavodoxin, deoxyhemoglobin, trypsin inhibitor, ribonuclease-S, and lysozyme. The sulfur-pi-bonded 'chains' involve a minimum of five and a maximum of 10 amino acids, and contain the most polarizable atoms within proteins. S-pi-chains give extra stability to the folding of proteins; they may also afford paths for the step-wise movement of electrons.
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PMID:Chains of alternating sulfur and pi-bonded atoms in eight small proteins. 20 19

The relationship between neutrophil polymorphonuclear leukocyte (PMN) locomotion and the exocytosis of neutrophil cytoplasmic granules was studied by assessing these processes in cells migrating through micropore filters and by measuring the effects of degranulating stimuli on PMN chemotaxis, orientation, adhesiveness, and ability to bind the chemoattractant f-Met-Leu-[3H]Phe. Studies of cells migrating through cellulose nitrate filters indicated that concentrations of f-Met-Leu-Phe optimal for exocytosis were greater than those optimal for chemotaxis and actually inhibited cell migration. In other studies incubation of PMNs with concentrations of secretagogues causing exocytosis of 30% or greater PMN lysozyme increased cell adhesiveness and inhibited chemotaxis. PMNs that had secreted more than 30% lysozyme appeared round, did not orient in a gradient of chemoattractant, and were capable of significantly less f-Met-Leu-[3H]Phe binding than were control cells. The decreased binding of f-Met-Leu-Phe was not associated with hydrolysis of chemotactic peptide by washed cells, although peptide hydrolysis was caused by cell products secreted extracellularly after vigorous exocytosis. In contrast, when only 10--15% cellular lysozyme was released f-Met-Leu-Phe binding was enhanced significantly and there was no depression of chemotaxis. The data indicate limited exocytosis of intracellular granule contents is associated with increased availability of PMN cehmotactic factor receptors. Vigorous exocytosis is associated with inactivation of chemotactic responsiveness related to increase cell adhesiveness, decreased PMN binding of chemotactic factors, and to hydrolysis of chemoattractants by factors secreted extracellularly.
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PMID:Role of secretory events in modulating human neutrophil chemotaxis. 37 35

A manual high-sensitivity sequencing method is described, in which 4-NN-dimethylaminoazobenzene 4'-isothiocyanate is used for the stepwise degradation of amino acid residues from the peptides. The 4-NN-dimethylaminoazobenzene 4'-thiazolinones of amino acids that were released, after conversion into their thiohydantoin derivatives, were identified by t.l.c. on polyamide sheets. This new method is simple and sensitive, and requires only 2-10nmol of peptides or proteins for extended sequence analysis. The method was tested on the sequence analysis of a hexapeptide (Leu-Trp-Met-Arg-Phe-Ala), bradykinin, glucagon and native lysozyme. Results show that the proposed procedure is a sensitive method for the sequence determination of short peptides as well as for the partial sequence determination of intact proteins.
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PMID:High-sensitivity sequence analysis of peptides and proteins by 4-NN-dimethylaminoazobenzene 4'-isothiocyanate. 40

A chemotactic peptide CHO.Met.Leu.Phe.OH has been synthesized classically using the mixed anhydride procedure. The formyl group was introduced by coupling formic acid in the presence of dicyclohexylcarbodiimide to the partially protected triptide. The final product was obtained by treatment of the intermediate CHO.Met.Leu.Phe.OBzl with hydrogen fluoride. The ED50 of the peptide in the Boyden chamber assay was 7 x 10(-11) M; in the lysozyme release assay 2.4 x 10(-10) M and in the beta-glucuronidase release assay 2.6 x 10(-10) M. In a radioreceptor assay the ID50 of the peptide was 3.3 x 10(-10) M.
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PMID:Synthesis of Nalpha-formyl-Met-Leu-Phe-OH: an inducer of chemotaxis in peritoneal polymorphonuclear neutrophils. 42 7

The translation of ovomucoid mRNA in a reticulocyte lysate protein-synthesizing system yields a precursor form which contains an NH2-terminal extension of 23 amino acid residues. Edman degradation of radioactive translation products (pre-ovomucoid) identified the following sequence: formula : (see text), where the initiator methionine (in parentheses) is the only residue cleaved from the NH2 terminus during cell-free synthesis and the vertical line indicates the site at which pre-ovomucoid is cleaved in vivo to yield ovomucoid. The precursor sequence differs from those of two other proteins (pre-lysozyme and pre-conalbumin) secreted by the same cell, but resembles these and other secretory protein "signal peptides" in both length and hydrophobicity. Pre-ovomucoid does not interact with trypsin in the same manner as mature ovomucoid.
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PMID:Precursor of egg white ovomucoid. Amino acid sequence of an NH2-terminal extension. 72 26

Lysozyme-sensitive mutants of Mycobacterium smegmatis, isolated by nitrosoguanidine treatment, have been converted into protoplasts in a nutritionally enriched medium containing lysozyme and DL-methionine.
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PMID:Protoplast formation of selected Mycobacterium smegmatis mutants by lysozyme in combination with methionine. 84 26

The in vivo incorporation of L-[Me-3H]methionine into egg white lysozyme of the laying hen has been examined. Using a versatile synthetic chicken diet which consisted of 75% free amino-acid ration and 25% normal laying ration, 5-8% incorporation of the [3H]methionine into lysozyme was demonstrated. The utility of this vertebrate in vivo incorporation technique is discussed in terms of its application to the incorporation of 13C-enriched amino acids into vertebrate proteins as a prelude to macromolecular 13C nuclear magnetic resonance studies.
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PMID:In vivo incorporation of isotopically labelled amino acids into vertebrate proteins: L-[Me-3H]methionine incorporation into chicken egg white lysozyme. 85 89


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