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)

By application of pulse radiolysis it was demonstrated that nitrogen dioxide (NO2.) oxidizes Gly-Tyr in aqueous solution with a strongly pH-dependent rate constant (k6 = 3.2 X 10(5) M-1 S-1 at pH 7.5 and k6 = 2.0 X 10(7) M-1 S-1 at pH 11.3), primarily generating phenoxyl radicals. The phenoxyl can react further with NO2. (k7 approximately 3 X 10(9) M-1 S-1) to form nitrotyrosine, which is the predominant final product in neutral solution and at low tyrosyl concentrations under gamma-radiolysis conditions. Tyrosine nitration is less efficient in acidic solution, due to the natural disproportionation of NO2., and in alkaline solutions and at high tyrosyl concentrations due to enhanced tyrosyl dimerization. Selective tyrosine nitration by interaction of NO2. with proteins (at pH 7 to 9) was demonstrated in the case of histone, lysozyme, ribonuclease A, and subtilisin Carlsberg. Nitrotyrosine developed slowly also under incubation of Gly-Tyr with nitrite at pH 4 to 5, where NO2. is formed by acid decomposition of HONO. It is recalled in this context that NO2.-induced oxidations, by regenerating NO2-, can propagate NO2./NO2- redox cycling under acidic conditions. Even faster than with tyrosine is the NO2.-induced oxidation of cysteine-thiolate (k9 = 2.4 X 10(8) M-1 S-1 at pH 9.2), involving the transient formation of cystinyl radical anions. The interaction of NO2. with Gly-Trp was comparably slow (k approximately 10(6) M-1 S-1), and no reaction was detectable by pulse radiolysis with Met-Gly and (Cys-Gly)2, or with DNA. Slow reactions of NO2. were observed with arachidonic acid (k approximately 10(6) M-1 S-1 at pH 9.0) and with linoleate (k approximately 2 X 10(5) M-1 S-1 at pH 9.4), indicating that NO2. is capable of initiating lipid peroxidation even in an aqueous environment. NO2.-Induced tyrosine nitration, using 50 microM Gly-Tyr at pH 8.2, was hardly inhibited, however, in the presence of 1 mM linoleate, and was not affected at all in the presence of 5 mM dimethylamine (a nitrosamine precursor). It is concluded that protein modifications, and particularly phenol and thiol oxidation, may be an important mechanism, as well as initiation of lipid peroxidation, of action of NO2. in biological systems.
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PMID:Reactions of nitrogen dioxide in aqueous model systems: oxidation of tyrosine units in peptides and proteins. 406 99

Increased production of sinefungin, a very potent antifungal and antiparasitic nucleoside antibiotic was achieved by medium and strain improvement. When soybean-meal, dextrin and yeast extract were added as carbon and nitrogen sources to the fermentation medium, instead of corn steep liquor, soya-oil and glucose; the antibiotic yield increased from 40 micrograms/ml to 126 micrograms/ml with low biomass production. Strain improvement was attempted by two methods. The mean antibiotic yield of the variants after multistep mutagenesis by N-methyl-N'-nitro-N-nitrosoguanidine and ethyleneimine was 466 micrograms/ml. Protoplasts of the parental strain were prepared by lysozyme digestion from mycelia grown in a medium containing 0.7% glycine. The mean activity of the regenerated protoplasts was 664 micrograms/ml. Thus, the overall sinefungin production could be increased 16-fold.
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PMID:Enhanced sinefungin production by medium improvement, mutagenesis and protoplast regeneration of Streptomyces incarnatus NRRL 8089. 406 2

This study investigated the potential for nephrotoxicity of gentamicin in cats by measuring marker enzyme concentrations, [Na], [K], osmolality, and pH of the urine, and blood urea nitrogen (BUN) levels. Gentamicin was administered i.m. at 4.4 mg/kg once daily (s.i.d.) or twice daily (b.i.d.) for 7 days. Concentrations of lactic dehydrogenase (LDH), lysozyme (LZM), alkaline phosphatase (AP), and glutamate dehydrogenase (GD) were measured as total 24-h excretions. The s.i.d. regimen produced only a slight increase in LDH excretion after 5 days, whereas the b.i.d. regimen caused an increase in the excretion of all enzymes. The greatest elevations were observed for LZM and LDH. Of the enzymes studied, these appeared to be the most appropriate to monitor for potential nephrotoxicity, except that urinary concentrations did not correlate well with duration of gentamicin administration. Only slight elevations in BUN were observed for either regimen. Single daily administration increased urine osmolality slightly, but b.i.d. treatment caused a marked and immediate decrease in urine osmolality, [Na], and total Na excretion. Urinary [K] was also depressed, as was total K excretion after 6 days. Urine pH was not substantially affected. This study showed that the recommended daily dose of 4.4 mg/kg produced little if any evidence of nephrotoxicity as indicated by the parameters measured. Twice daily dosing, however, produced elevations in urine enzyme concentrations, and markedly decreased urine osmolality and Na and K excretion. Compared to other species studied, the cat appears particularly sensitive to urine concentrating alterations resulting from repeated gentamicin administration.
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PMID:The nephrotoxic potential of gentamicin in the cat: enzymuria and alterations in urine concentrating capability. 409 28

As a first step towards the production of a lysed BCG vaccine that would have reduced toxicity and allergenicity and yet be immunogenic, the growth and lysis of BCG bacilli under strictly controlled conditions have been studied.BCG grown in both Dubos and Aldridge liquid media showed an arithmetic linear growth, preceded by a very short logarithmic phase. This suggested that some of the cell population became metabolically inactive at a very early stage, possibly owing to suboptimal conditions of growth.Glycine, lysozyme and lithium chloride initiated lysis of BCG growth in the aforementioned media 24-48 hours after inoculation. After 2 weeks' incubation approximately 50% of the original BCG culture was lysed and the viable count had fallen 1000-fold. The autolytic pattern of BCG in a nitrogen-deficient, chemically defined Aldridge medium is also described.
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PMID:Lysed BCG vaccines. 1. Observations on optimal conditions for BCG growth and lysis. 487 14

The authors have attempted to prepare lysed BCG vaccines retaining the protective antigens of the BCG cell wall and yet eliciting in experimental animals limited sensitivity to the tuberculin substances, the advantage sought being to retain the usefulness of the tuberculin following vaccination as an indicator of superinfection.Experimental vaccines were prepared by growing and lysing BCG in both Dubos and Aldridge liquid media with glycine, lysosyme and lithium chloride; vaccines were also prepared by autolysis in Aldridge nitrogen-deficient, chemically defined medium.Glycine, lysozyme and lithium chloride significantly reduced both the protective and allergenic properties of the lysates. The best protection was afforded by BCG cells autolysed in Aldridge medium. Treatment of the BCG autolysates with lysozyme alone did not affect the protective capability of the vaccines and almost completely eliminated the allergenicity. It is suggested that these BCG lysates contain metabolically inactive cells, which do not multiply in vitro but may still provide sufficient antigen in vivo to ensure protection.
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PMID:Lysed BCG vaccines. 2. The effect of lysis on the immunogenicity and allergenicity of BCG vaccines. 530 50

Cells of Azotobacter vinelandii encysted in Burk's nitrogen-free liquid media which had been supplemented with n-butyl alcohol, beta-hydroxybutyrate, or crotonate. Butyraldehyde and butyrate did not influence the extent of encystment. In the absence of glucose, beta-hydroxybutyrate enhanced the rate and extent of encystment. In the presence of glucose, it promoted abortive encystment, which was manifested by the disorganization of the exine and the release of a highly viscous material into the medium. The soluble, viscous polymer was separated from the medium by a series of ethyl alcohol precipitations and identified as a mucopeptide. It was cleaved by treatment with lysozyme and lysostaphin with a concomitant increase in reducing power. It contained 13.9% N; 56% amino acids, as alanine (alanine, lysine, and glutamic acids); and 42% hexosamines. The polymer appeared to be similar to a noncross-linked peptidoglycan.
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PMID:Encystment and polymer production by Azotobacter vinelandii in the presence of beta-hydroxybutyrate. 566 5

1. The mucopeptide component of wall preparations from Bacillus licheniformis was obtained in soluble form by treatment of the acid-insoluble residue of walls with lysozyme. 2. The soluble mucopeptide contains glutamic acid, diaminopimelic acid, alanine, N-acetylglucosamine and N-acetylmuramic acid in the molecular proportions 1.0:1.0:1.6:0.8:0.7. In addition approx. 1 mole of amide/mole of glutamic acid is present. Essentially all of the dry weight and nitrogen content of soluble mucopeptide is accounted for by these constituents. 3. The optical configurations of the amino acids were determined. Approx. 0.6 mole of d-alanine and 1.0 mole of l-alanine are present/mole of glutamic acid. 4. The structures of several small peptides derived from soluble mucopeptide after mild acid hydrolysis were established. 5. The structure of soluble mucopeptide from B. licheniformis is discussed on the basis of these results together with data on the number of free amino groups present in soluble mucopeptide.
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PMID:The cell wall of Bacillus licheniformis N.C.T.C. 6346. Composition of the mucopeptide component. 572 70

The isolation of a new thermophilic bacterium, Thermus aquaticus gen. n. and sp. n., is described. Successful enrichment requires incubation at 70 to 75 C, and the use of nutrient media relatively dilute with respect to the organic components. Strains of T. aquaticus have been isolated from a variety of thermal springs in Yellowstone National Park and from a thermal spring in California. The organism has also been isolated from man-made thermal habitats, such as hot tap water, in geographical locations quite distant from thermal springs. Isolates of T. aquaticus are gram-negative nonsporulating nonmotile rods which frequently form long filaments at supraoptimal temperatures or in the stationary phase. All isolates form a yellow cellular pigment, probably a carotenoid. A characteristic structure formed by all isolates is a large sphere, considerably larger than a spheroplast. These large spheres, as well as lysozyme-induced spheroplasts, are resistant to osmotic lysis. Deoxyribonucleic acid base compositions of four strains were determined by CsCl density gradient ultracentrifugation and found to be between 65.4 and 67.4 moles per cent guanine plus cytosine. The growth of all isolates tested is inhibited by fairly low concentrations of cycloserine, streptomycin, penicillin, novobiocin, tetracycline, and chloramphenicol. Nutritional studies on one strain showed that it did not require vitamins or amino acids, although growth was considerably faster in enriched than in synthetic medium. Several sugars and organic acids served as carbon sources, and either NH(4) (+) or glutamate could serve as nitrogen source. The organism is an obligate aerobe and has a pH optimum of 7.5 to 7.8. The optimum temperature for growth is 70 C, the maximum 79 C, and the minimum about 40 C. The generation time at the optimum is about 50 min. The possible relationships of this new genus to the myxobacteria, flexibacteria, and flavobacteria are discussed.
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PMID:Thermus aquaticus gen. n. and sp. n., a nonsporulating extreme thermophile. 578 80

A microorganism resembling an Actinomyces species was found to be a numerically predominant inhabitant of various organically rich soils. This organism forms a hyphal-like structure with true branching that fragments into gram-positive diphtheroid and coccoid elements. Its cells ferment carbohydrates and contain both lysine and ornithine as the major basic amino acids of the cell wall. It is catalase-negative, microaerophilic to aerobic, and sensitive to lysozyme, and it is dependent on an organic nitrogen source and incubation at 30 C for optimum growth. Based on these characteristics, a new species, Actinomyces humiferus, is proposed. The ecological and medical implications of a large soil population of this microorganism are discussed.
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PMID:Predominant catalase-negative soil bacteria. II. Occurrence and characterization of Actinomyces humiferus, sp. N. 580 24

In order to resolve discrepancies in the literature concerning the subcellular localization of NADPH oxidase, we disrupted human neutrophils by nitrogen cavitation and fractionated the subcellular organelles on a discontinuous sucrose density gradient. The lightest fraction was 20- to 40-fold enriched for plasma membranes as determined by the marker enzymes alkaline phosphatase and phosphodiesterase I as well as by the ratio of lipid phosphorus to protein. There was a significant decrease in the specific activities of the granule markers myeloperoxidase, lysozyme, and beta-glucuronidase. An intermediate fraction was enriched in membrane markers but not to the extent the lightest fraction was enriched. This fraction contained more granular contamination, as shown by the marker enzymes. In contrast, the densest bands of the gradient were enriched for granule markers with little contamination by plasma membrane. Superoxide generation and NADP formation were primarily associated with the two membrane-enriched fractions from polymorphonuclear leukocytes stimulated with phorbol myristate acetate. The NADP formation associated with a dense granule fraction observed previously in our laboratory was probably due to a cyanide-stimulated oxidation of NADPH by myeloperoxidase.
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PMID:Co-localization of superoxide generation and NADP formation in plasma membrane fractions from human neutrophils. 609 76


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