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)

The localization of D-lactate dehydrogenase in membrane vesicles prepared from Escherichia coli was studied using antibody against the purified enzyme. The activity of D-lactate dehydrogenase and D-lactate-dependent oxygen uptake of membrane vesicles prepared by using a French press were completely inhibited by this antibody, suggesting that the enzyme is localized on the outside of these vesicles. This and previous results (Futai, 1974) strongly indicate the inversion of these vesicles. The D-lactate dehydrogenase and D-lactate-dependent oxygen uptake of membrane vesicles prepared by treatment with ethylenediaminetetraacetate-lysozyme were inhibited about 15% by the antibody, whereas proline transport of the vesicles was insensitive to antibody. These results suggest that most of the membrane vesicles have D-lactate dehydrogenase on the inside of the membrane and that such vesicles transport amino acids. This essentially confirms the results of Short, Kaback, and Kohn (1975). However, unlike them we observed that a small but significant portion of activity was sensitive to the antibody as shown above. This portion may represent the completely inverted vesicles in the preparation. Ferricyanide reductase activity cannot be detected in spheroplasts, but about 30 to 50% of the total was detected in membrane vesicles prepared by treatment with ethylenediaminetetraacetate. This confirms our previous findings with membrane prepared by a slightly different procedure. It is concluded that in these vesicles about half the reactive sites for ferricyanide are moved from inside to outside the membrane, whereas 85% of the D-lactate dehydrogenase remains inside the membrane.
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PMID:Localization of D-lactate dehydrogenase in membrane vesicles prepared by using a french press or ethylenediaminetetraacetate-lysozyme from Escherichia coli. 80 22

Granulocytes were harvested from each of five healthy male volunteers once by continuous flow centrifugation with the IBM-Aminco Celltrifuge, and once by adhesion filtration leukapheresis with nylon fiber. Granulocyte recovery and purity were significantly better with the filtration leukapheresis system than with continuous flow centrifugation. Measurements of trypan blue dye exclusion and muramidase activity were similar to those in control granulocytes regardless of the method of isolation. Granulocyte-stimulated oxygen consumption was diminished in granulocytes prepared by the adhesion filtration method, but normal in those prepared by continuous flow centrifugation with the IBM-Aminco Celltrifuge.
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PMID:In vitro function of granulocytes isolated from blood of normal volunteers using continuous-flow centrifugation in the IBM-aminco celltrifuge and adhesion-filtration leukapheresis using nylon fiber. 85 Sep 31

The enzymic hydrolysis of some proteins (insulin-B-chain-S-sulfonate, S-aminoethylated lysozyme, bovine serum albumin) by immobilized peptidolytic enzymes is reported. Sepharose-bound pronase, trypsin and a protease from Thermoactinomyces sp. (MP), the latter both cross linked by glutaric dialdehyde and an exopeptidase mixture containing Sepharose-bound leucine aminopeptidase, carboxypeptidase A and a crude preparation of prolidase were used. After enzymic hydrolysis nearly all amino acids, except proline, were recovered in a 100% yield compared to the value of an acid reference hydrolysate. Tryptophan and methionine, which are partially destroyed by acid hydrolysis in the presence of oxygen could be recovered completely.
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PMID:[Protein hydrolysis by immobilized enzymes]. 98 21

Peptide analysis of tryptic hydrolysates of two lysozyme forms derived from oxidation of lysozyme with singlet oxygen shows that Trp-62, located at the active site, is destroyed. This is confirmed by the protective effect of the substrate (chitin), whose presense practically prevents the oxidation. A possibility of oxidating different tryptophan residues is discussed from the view-point of their availability to the reagent.
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PMID:[Selectivity of lysozyme oxidation by singlet oxygen]. 102 93

Microorganisms ingested by PMNs are exposed to a variety of antimicrobial systems. Together they comprise a formidable armamentarium, and few organisms survive. The predominant antimicrobial system would be expected to vary with the species, the availability of oxygen and the type of microorganism ingested. There is considerable evidence that the MPO-mediated antimicrobial system plays an important role in the destruction of certain microorganisms in most species; chicken heterophils, however, do not contain MPO,40 and some microorganisms are resistant to this system due to the nature of their cell wall material.146 Further, microbial catalase may offer some protection. The granulocytes of some species (e.g., rabbit, chicken) are rich in cationic proteins and these agents may play a particularly important role in these cells. Granular cationic proteins are less plentiful in human cells.111 Organisms vary in their susceptibility to lysozyme and this enzyme is absent from bovine leukocytes.113 It is probable that the total microbicidal potential of the leukocyte is in excess of its needs under most circumstances. This "overkill" capacity is a reflection of both the level of activity of individual systems and their variety. Particular organisms are susceptible to more than one antimicrobial system and thus may be effectively handled by back-up systems when one is absent. Thus, an organism normally killed by the peroxidase system may be handled less efficiently but adequately when MPO is absent by other oxygen-dependent antimicrobial systems. When a defect in oxidative metabolixm is present as in CGD, both MPO-catalyzed and nonenzymatic oxygen-dependent systems are absent. The ingested organism can, in some instances, supply the needed product of oxidative metabolism (i.e., H2O2); in other instances, oxygen-independent antimicrobial systems are adequate to prevent microbial growth. However, in yet other instances, the organisms survive and multiply and severe infection results.
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PMID:Antimicrobial mechanisms in neutrophilic polymorphonuclear leukocytes. 111 38

Polymorphonuclear leucocytes (PMN), monocytes and monocyte-derived macrophages were capable of interacting with opsonized C. albicans in both aerobic and anaerobic conditions. Superoxide anion release by these cells was inhibited in anaerobic conditions while lysozyme release and phagocytosis were equally efficient in both aerobic and anaerobic conditions. All cell types tested were capable of intracellular killing of C. albicans and this appeared to be maximum at 6 h for monocytes and macrophages and 24 h for PMN. Monocytes killed the lowest number of organisms, 1 x 10(6), and the killing was similar for aerobic and anaerobic conditions. In contrast, PMN and macrophages demonstrated greater killing of C. albicans in aerobic conditions compared with anaerobic conditions; PMN killed 1.9 x 10(6) organisms and macrophages 3 x 10(6) when incubated anaerobically. Inhibitors of oxygen metabolism decreased intracellular killing of C. albicans by macrophages and PMN in aerobic but not anaerobic conditions. The oxygen reaction products involved in the killing of C. albicans appeared to be different however: macrophage killing was decreased by superoxide anion and hydrogen peroxide inhibitors. PMN killing was decreased by superoxide anion, hydrogen peroxide, hypochlorous acid and hydroxyl radical inhibitors. The present study shows that although monocytes, macrophages and PMN function similarly in their interaction with C. albicans, they appear to use different oxygen reactive products for the intracellular killing of C. albicans.
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PMID:Interaction and intracellular killing of Candida albicans blastospores by human polymorphonuclear leucocytes, monocytes and monocyte-derived macrophages in aerobic and anaerobic conditions. 131 Apr 54

Fluosol (Alpha Therapeutic Corporation, Los Angeles, CA) an emulsion of perfluorocarbons with a high oxygen-carrying capacity, was approved as an adjunct to alleviate myocardial ischemia during coronary angioplasty. This drug also significantly enhances myocardial salvage presumably related to an action on the neutrophil. The mechanism by which fluosol and its individual components, including the detergent Pluronic F-68, affected neutrophil function was examined. During the incubation of neutrophils with fluosol, a rapid stimulation of superoxide anion production and degranulation which progressively increased over a 30-minute period was detected. Neutrophils incubated with only Pluronic F-68 produced similar amounts of superoxide anion. Cytochalasin B, an inhibitor of phagocytosis, significantly inhibited this superoxide anion generation. As shown previously, neutrophils incubated with fluosol for 30 minutes and then subsequently stimulated manifested a reduction in lysozyme release as compared with untreated cells. Results of an electron microscopic examination confirmed the cellular uptake of the fluosol within phagocytic vacuoles. Neutrophil viability determined by trypan blue was unaffected after fluosol treatment. These observations show that the fluosol emulsion, primarily through micelles formed by the detergent Pluronic F-68, activates human neutrophils by serving as a phagocytic stimulus, which produces a cell refractory to subsequent stimulation.
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PMID:Phagocytic activation of human neutrophils by the detergent component of fluosol. 131 83

Neutrophil (PMN) contributions to the acute inflammatory process and host defense include generation of bioreactive oxygen metabolites and secretion of granule enzymes. We assessed equine PMN secretion using several PMN stimuli, singly and in combination with bacterial lipopolysaccharide (LPS). LPS avidly associated with equine PMN, as shown by strong PMN labeling with FITC-conjugated LPS. LPS alone (1 or 10 micrograms ml-1) was a weak stimulus for PMN superoxide anion (O2-) generation, but preincubation with LPS followed by phorbol ester (PMA, 10 ng ml-1) significantly augmented (P less than 0.01) secretion of O2- (19.38 nmol O2- per 2 x 10(6) PMN per 5 min) over the amount generated by PMA stimulation alone (13.75 nmol O2-). A qualitatively similar, but smaller O2(-)-generation response occurred when either opsonized zymosan or recombinant human C5a was used as the PMN stimulus. Arachidonic acid (ArA; 50-200 microM) was a potent stimulus, with secreted O2- levels similar to those from PMA-stimulated PMN. Preincubation of PMN with either the formyl peptide, fMLP, or platelet-activating factor before stimulation with ArA did not significantly increase O2- generation over levels obtained using ArA alone. Release of PMN granule enzymes was also quantitated. A small amount of lysozyme secretion resulted when PMN were exposed to LPS alone (8.20% of total cell content), and PMA stimulation caused marked release of PMN lysozyme (44.45%). Non-specific proteolytic activity in PMN supernatants, assessed by cleavage of a collagen-rich substrate, was minimal with LPS as a sole stimulus (5.08%). There was significant proteolytic activity (P less than 0.01) in supernatants from PMA-stimulated PMN (27.21%), and preincubation with LPS followed by PMA stimulation slightly enhanced (P less than 0.05) the release of PMN proteases (34.62%). The activities of beta-glucuronidase, acid phosphatase, and alkaline phosphatase were minimal in PMN supernatants when using LPS and PMA as stimuli. The activity of PMN granule enzymes was found to be sensitive to the presence of normal equine serum, and proteolytic activity was markedly reduced (80.13% reduction) in the presence of 10% pooled serum.
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PMID:Secretory activity of equine polymorphonuclear leukocytes: stimulus specificity and priming effects of bacterial lipopolysaccharide. 131 72

The cell activation inhibitor CI-959 [5-methoxy-3-(1-methyl-ethoxy)-N-1H- tetrazol-5-ylbenzo[b]thiophene-2-carboxamide, monosodium salt] was evaluated for its effect on the activation of human eosinophils, macrophages, and neutrophils by the phagocytic stimulus serum-opsonized zymosan (SOZ). CI-959 inhibited the respiratory burst of eosinophils and neutrophils, measured as the generation of superoxide anion, with IC50s of 9.6 and 14.5 microM, respectively. In contrast, 100 microM CI-959 inhibited superoxide anion generation by human macrophages by only 22.7%. The compound exhibited a different inhibition profile for lysosomal enzyme release from these cells. At 100 microM, CI-959 inhibited the release of eosinophil peroxidase and macrophage N-acetyl-beta-D-glucosaminidase by only 19.5 and 25.6%, respectively. In contrast, CI-959 inhibited the release of the neutrophil primary granule enzyme myeloperoxidase with an IC50 of 7.5 microM, while inhibiting release of lysozyme from secondary granules by only 11.4% at 100 microM. These results demonstrate that oxygen radical generation and lysosomal enzyme release by human leukocyte populations are differentially regulated by CI-959.
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PMID:Differential regulation of human eosinophil, macrophage, and neutrophil functions by the allergic mediator release inhibitor CI-959. 132 46

The site-specific lysozyme damage by iron and by iron-catalysed oxygen radicals was investigated. A solution of purified lysozyme was inactivated by Fe(II) at pH 7.4 in phosphate buffer, as tested on cleavage of Micrococcus lysodeikticus cells; this inactivation was time- and iron concentration-dependent and was associated with a loss of tryptophan fluorescence. In addition, it was reversible at pH 4, as demonstrated by lysozyme reactivation and by the intensity of the 14.4-kD-band on SDS-PAGE. Desferal (1 mM) and Detapac (1 mM) added before iron, prevented lysozyme inactivation, while catalase (100 micrograms/ml), superoxide dismutase (100 micrograms/ml) and bovine serum albumin (100 micrograms/ml) gave about 30 to 40% protection by competing with lysozyme for iron binding. The denaturing effect of iron on lysozyme was studied in the presence of H2O2 (1 mM) and ascorbate (1 mM); under these conditions the enzyme underwent partly irreversible inactivation and degradation different to that produced by gamma radiolysis-generated .OH. Catalase almost fully protected lysozyme; in contrast, mannitol (10 mM), benzoate (10 mM), and formate (10 mM) provided no protection because of their inability to access the site at which damaging species are generated. In this system, radical species were formed in a site-specific manner, and they reacted essentially with lysozyme at the site of their formation, causing inactivation and degradation differently than the hydroxyl radical.
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PMID:Mechanism of lysozyme inactivation and degradation by iron. 133 14


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