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)

Legionella pneumophila infection of guinea-pigs by the aerosol route with either of two strains, one (serogroup I) giving an acute the other (serogroup 3) giving a protracted illness, induced a pyrexia and similar pneumonic lesions. With both strains there was a bacteraemia with early decreases in serum iron and zinc and increases in serum copper concentrations. Marked changes in other serum components were evident only in those animals which had protracted illness (serogroup 3-infected animals). These included transient increases in aminotransferase, creatine kinase and sorbitol dehydrogenase activities and triglyceride levels, together with gradual decreases in alkaline phosphatase and leucine aminopeptidase activities. Serum lysozyme activity and acute-phase protein synthesis increased, as did the ratio of phenylalanine to tyrosine. The findings confirm the relevance of the aerosol-infected guinea-pig model for the investigation of the disease processes and evaluation of therapeutic measures for use in man.
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PMID:Clinical chemical responses to experimental airborne legionellosis in the guinea-pig. 258 May 46

The determinants recognized by two I-Ak-restricted hen egg-white lysozyme-specific T cell hybridomas were differentiated with a series of truncated or substituted peptides. The 10mer 52-61 was the smallest peptide that was immunogenic for both T cells. This peptide differed by a single residue, Leu56, from the corresponding autologous lysozyme peptide, which was nonimmunogenic. The addition of amino acids to the amino terminus of 52-61 increased the immunogenicity of the peptides for 3A9 T cells and decreased the immunogenicity for 2A11 T cells. By deleting or diiodinating Tyr53, the resulting peptides were rendered totally nonimmunogenic. In contrast, the 3-NO2-Tyr derivative was fully immunogenic for the 3A9 cells but completely nonimmunogenic for the 2A11 cells. Thus, two different, but very similar, determinants were generated by the same HEL peptide and the I-Ak molecule.
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PMID:Specificity of the T cell receptor: two different determinants are generated by the same peptide and the I-Ak molecule. 258 39

Expression of the proto-oncogene p93c-fes and its associated tyrosine kinase activity is marked in mature granulocytes, monocytes, differentiated HL-60 leukemia cells, and leukemia cell lines KG-1, THP-1, HEL, and U-937, which can be induced to differentiate along the granulocyte/monocyte pathway. Conversely, p93-c-fes expression is absent in the K562 cell line, which is resistant to myeloid differentiation. Upon transfection and clonal selection of K562 cells using a mammalian expression vector containing the 13-kilobase pair c-fes gene, c-fes mRNA was transcribed and p93-c-fes tyrosine activity kinase was expressed. Clones expressing c-fes underwent myeloid differentiation as assessed by the appearance of phagocytic activity, Fc receptors, nitro blue tetrazolium reduction, Mac-1 immunofluorescence, and lysozyme production. These results indicate that the expression of the c-fes protooncogene and its associated tyrosine kinase activity plays a major role in the initiation of myeloid differentiation.
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PMID:K562 leukemia cells transfected with the human c-fes gene acquire the ability to undergo myeloid differentiation. 265 6

Multiple replacements at amino acid position 3 of bacteriophage T4 lysozyme have shown that the conformational stability of the protein is directly governed by the hydrophobicity of the residue substituted (Matsumura, M., Becktel, W. J., and Matthews, B. W. (1988) Nature 334, 406-410). Of the 13 mutant lysozymes made by site-directed mutagenesis, two variants, one with valine (I3V) and the other with tyrosine (I3Y), were crystallized and their structures solved. In this report we describe the crystal structures of these variants at 1.7 A resolution. While the structure of the I3V mutant is essentially the same as that of wild-type lysozyme, the I3Y mutant has substantial changes in its structure. The most significant of these are that the side chain of the tyrosine is not accommodated within the interior of the protein and the amino-terminal polypeptide (residues 1-9) moves 0.6-1.1 A relative to the wild-type structure. Using coordinates based on the wild-type and available mutant structures, solvent accessible surface area of residue 3 as well as the adjacent 9 residues in the folded form were calculated. The free energy of stabilization based on the transfer of these residues from a fully extended form to the interior to the folded protein was found to correlate well with the protein stability determined by thermodynamic analysis. The enhanced thermostability of the variant Ile-3----Leu, relative to wild-type lysozyme, can also be rationalized by surface-area calculations based on a model-built structure. Noncrystallization of most lysozyme variants at position 3 appears to be due to disruption of intermolecular contacts in the crystal. The Ile-3----Val variant is closely isomorphous with wild-type and maintains the same crystal contacts. In the Ile-3----Tyr variant, however, a new set of contacts is made in which direct protein-protein hydrogen bonds are replaced by protein-water-protein hydrogen bonds as well as a novel hydrogen bond involving the phenolic hydroxyl of the substituted tyrosine.
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PMID:Structural studies of mutants of T4 lysozyme that alter hydrophobic stabilization. 267 24

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 quenching of the benzophenone triplet by lysozyme and its constituent amino acids in aqueous solutions have been studied. Native lysozyme quenches the benzophenone triplet with a high rate constant, 4 x 10(9) M-1 s-1. The quenching process takes place with production of significant amounts of free ketyl radicals, phi ketyl = 0.56, but with a very low benzophenone consumption yield (0.022). The consumption yield is considerably smaller than that observed for the free amino acids. This difference can be explained in terms of a dominant back hydrogen transfer to the protein in the disproportionation of the free radicals produced. Reduced and carboxymethylated lysozyme shows a higher quenching rate (7.8 x 10(9) M-1 s-1) and a larger benzophenone consumption yield (0.07). The deactivation of the benzophenone triplet by the native protein leads to its inactivation, with a quantum yield of 0.01. Tryptophan and arginine residues are destroyed with a quantum yield of 0.01. In the modified enzyme tyrosine and methionine groups are also consumed.
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PMID:Photointeraction of benzophenone triplet with lysozyme. 275 90

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

A cloned, virus-producing, tumorigenic, promonocytic leukemia cell line, AC8, derived from an Abelson murine leukemia virus-infected mouse can differentiate in vitro. Differentiated cells, purified from a population containing undifferentiated cells on the basis of expression of the macrophage differentiation antigens Mac-1 (C3 receptor) and F4/80, were phagocytic, produced lysozyme, were less tumorigenic, and had a reduced replicative capacity compared with undifferentiated cells. Differentiated cells produced less infectious Abelson virus than undifferentiation. Cloning studies indicated that differentiation was the cause rather than the effect of reduced Abelson virus production. However, the intracellular amount and the tyrosine-specific protein kinase activity of the Abelson virus oncogene product, P120v-abl, were not affected by differentiation of the leukemic cells. Thus, these results show that Abelson virus-transformed myeloid lineage cells can differentiate without expression of the viral oncogene product being affected, which implies, in turn, that P120v-abl expression is not sufficient for maintaining transformation by blocking differentiation.
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PMID:Viral oncogene expression during differentiation of Abelson virus-infected murine promonocytic leukemia cells. 283 50

This report describes the purification of the major protein-tyrosine-phosphatases from human placenta. Enzyme activity was followed with a novel artificial substrate, namely reduced, carboxamidomethylated, and maleylated lysozyme, phosphorylated on tyrosine by a partially purified preparation of insulin and epidermal growth factor receptor kinases, also from human placenta. The key step in the purification of the protein-tyrosine-phosphatases was affinity chromatography on a column of thiophosphorylated, reduced, carboxamidomethylated, and maleylated lysozyme-Sepharose. Purification was carried out separately from both the soluble and particulate fractions. Whereas multiple and distinct enzyme forms were obtained from each of these, little difference could be detected between the behavior of the "soluble" enzyme subtypes and their "particulate" counterparts. The major subtypes were purified to apparent homogeneity with an approximately 23,000-fold enrichment and 10% yield from the soluble fraction and a 4,300-fold enrichment and 13% yield from the particulate fraction. Both samples migrated as bands of 35 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and had specific activities of approximately 45,000 nmol of Pi released min-1 mg-1, at least 2-3-fold higher than that of the type 1 and 2A serine/threonine phosphatases. The level of protein-tyrosine-phosphatases in the soluble fraction of human placenta (2,000 units/g of protein) was approximately the same as protein-serine/threonine-phosphatases 1 and 2A in skeletal muscle.
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PMID:Purification of the major protein-tyrosine-phosphatases of human placenta. 283 86

Three human lysozymes containing a mutation either at Asp-53 to Glu or at Tyr-63 to Trp or Phe were synthesized and examined for their immunological and enzymatical activities in comparison with the native one. All mutants were immunologically indistinguishable from native human lysozyme. The [Trp63] and [Phe63] mutants catalysed the hydrolysis of Micrococcus lysodeikticus cell wall and glycol chitin effectively, while the [Glu53] mutant displayed very low activity toward M. lysodeikticus cells and no detectable activity toward glycol chitin.
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PMID:Engineering of the active site of human lysozyme: conversion of aspartic acid 53 to glutamic acid and tyrosine 63 to tryptophan or phenylalanine. 288 Jun 6


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