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 post-nuclear fraction of rat heart tissue was fractionated by isopycnic zonal centrifugation in sucrose gradients, followed by differential centrifugation of the zonal fractions (rho-S fractionation). The distribution of 5 lysosomal acid hydrolases, a protease with neutral and alkaline activity and several marker enzymes for cell organelles (catalase, Ca2+-ATPase, cytochrome oxidase, glucose-6-phosphatase and muramidase) were studied. Three major lysosomal populations were described with equilibrium densities of 1.09, 1.17, and 1.23 gms cc-1 (omega2t = 1.54 X 10(11) rad2 sec-1), and a continuum in the size of these particles at the three different densities.
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PMID:Distribution of lysosome populations in rat cardiac tissue. 0 60

Degradation of myelin basic protein during incubations with high concentrations of horseradish peroxidase has been demonstrated [Johnson & Cammer (1977) J. Histochem. Cytochem.25, 329-336]. Possible mechanisms for the interaction of the basic protein with peroxidase were investigated in the present study. Because the peroxidase samples previously observed to degrade basic protein were mixtures of isoenzymes, commercial preparations of the separated isoenzymes were tested, and all three degraded basic protein, but to various extents. Three other basic proteins, P(2) protein from peripheral nerve myelin, lysozyme and cytochrome c, were not degraded by horseradish peroxidase under the same conditions. Inhibitor studies suggested a minor peroxidatic component in the reaction. Therefore the peroxidatic reaction with basic protein was studied by using low concentrations of peroxidase along with H(2)O(2). Horseradish peroxidase plus H(2)O(2) caused the destruction of basic protein, a reaction inhibited by cyanide, azide, ferrocyanide, tyrosine, di-iodotyrosine and catalase. Lactoperoxidase plus H(2)O(2) and myoglobin plus H(2)O(2) were also effective in destroying the myelin basic protein. Low concentrations of horseradish peroxidase plus H(2)O(2) were not active against other basic proteins, but did destroy casein and fibrinogen. Although high concentrations of peroxidase alone degraded basic protein to low-molecular-weight products, suggesting the operation of a proteolytic enzyme contaminant in the absence of H(2)O(2), incubations with catalytic concentrations of peroxidase in the presence of H(2)O(2) converted basic protein into products with high molecular weights. Our data suggest a mechanism for the latter, peroxidatic, reaction where polymers would form by linking the tyrosine side chains in basic-protein molecules. These data show that the myelin basic protein is unusually susceptible to peroxidatic reactions.
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PMID:Proteolytic and peroxidatic reactions of commercial horseradish peroxidase with myelin basic protein. 7 59

Polymorphonuclear leukocytes of rabbits and chickens after homogenization in 0.34 M saccharose or after multiple freezing and thawing were subjected to differential centrifugation at 150, 800, 10 000 and 50 000 X g. In the fractions obtained in this manner, total bactericidal activity as well as the activity of myeloperoxidase (E.C. 1. 11. 1. 7), catalase (E.C. 1.11.1.6), lysozyme (E.C. 3.2.1.17), cathepsin D (E.C. 3.4.4.23) and E, beta-D-glucuronidase (E.C. 3.2.1.31) and acid phosphatase (E.C. 3.1.3.2) were determined. Antibacterial activity was found in all fractions from rabbit leukocytes, but only in the first fraction from chick leukocytes. The fractions from rabbit leukocytes contained all enzymes under study while in the fractions from chicken leukocytes the presence of myeloperoxidase, catalase or cathepsin E could not be demonstrated. The highest bactericidal activity was found in the second obtained from the homogenate or rabbit leukocytes. The highest specific activity of myeloperoxidase and homogenate of rabbit leukocytes. The highest specific activity of myeloperoxidase and the lowest activity of cathepsin D were also demonstrated in this fraction. The addition of pepstatin to rabbit leukocytes before their disintegration resulted in the inhibition of the activity of cathepsin D and E and in an increase in the specific activity of myeloperoxidase as well as in total bactericidal activity in the individual fractions. These results testify that microbicidal mechanisms of phagocytes from individual species may differ and when the structure of lysosomes is damaged, the liberated hydrolytic enzymes may gradually inactivate antibacterial substances.
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PMID:Localization of antibacterial activity and hydrolytic enzymes in subcellular fractions of rabbit and chicken polymorphonuclear leukocytes. 17 6

Mechanisms were studied that might explain the attachment and damage to Candida albicans pseudohyphae by neutrophils in the absence of serum. Attachment of neutrophils to pseudo hyphae was inhibited by Candida mannans (1-10 mg/ml), but not by mannose, dextran, chitin, conconavalin A, or highly charged polyamino acids. Contact was also inhibited by pretreatment of Candida before incubation with neutrophils with chymotrypsin, but not trypsin or several inhibitors of proteases. Similar results were obtained with pretreatment of neutrophils, except that trypsin was inhibitory. When pseudohyphae were killed with ultraviolet light, proteinpolysaccharide complexes of mol wt <10,000 were released which appeared to bind to the surfaces of neutrophils and inhibit contact between neutrophils and Candida, as well as other fungi. Damage to Candida by neutrophils was inhibited by agents known to act on neutrophil oxidative microbicidal mechanisms, including sodium cyanide, sodium azide, catalase, superoxide dismutase, and 1, 4 diazobicyclo (2, 2, 2) octane, a singlet oxygen quencher. Neutrophils from a patient with chronic granulomatous disease did not damage Candida at all. However, the hydroxyl radical scavengers mannitol and benzoate were not inhibitory. Cationic proteins and lactoferrin also did not appear to play a major role in this system. Low concentrations of lysozyme which did not damage Candida in isotonic buffer solutions damaged pseudohyphae in distilled water. Isolated neutrophil granules damaged pseudohyphae only with added hydrogen peroxide and halide, and damage occurred only with granule fractions known to contain myeloperoxidase. These findings suggest that neutrophils recognized a molecule on the Candida surface which has a chymotrypsin sensitive protein component, and which may be liberated from the cell surface upon death of organism. The neutrophil receptors for Candida appear to be sensitive to trypsin and chymotrypsin. Damage to Candida by neutrophils occurred primarily by oxidative mechanisms, including the production of superoxide and hydrogen peroxide interacting with myeloperoxidase and halide, as well as singlet oxygen, but did not appear to involve hydroxyl radical. Lysozyme might have an accessory role, under some conditions.
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PMID:Mechanisms of attachment of neutrophils to Candida albicans pseudohyphae in the absence of serum, and of subsequent damage to pseudohyphae by microbicidal processes of neutrophils in vitro. 34 Apr 71

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

Positron annihilation studies have been carried out in two enzymes, lysozyme and catalase. Temperature dependence of the positron lifetimes in these two enzymes has been investigated. The results explained in terms of the free volume model and fluctuations between different conformational microstates of enzyme structures provide a new insight into the mechanism of bio-activity of these enzymes.
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PMID:Positron annihilation studies in lysozyme and catalase. 129 62

The role of free radical generation and its scavenging enzymes in circulating mice polymorphonuclear leukocytes (PMNLs) has been studied following pulmonary thromboembolism. Levels of malonaldehyde (MDA), 02- radical generation, activity of superoxide dismutase (SOD), catalase (CAT), lactate dehydrogenase (LDH), myeloperoxidase (MPO) and lysozyme were estimated in lysed neutrophil preparations. Activities of SOD and CAT were increased in neutrophils, while animals showed 60 +/- 4% thrombocytopenia. Levels of MDA in PMNLs were also elevated significantly following thrombosis. However, there was no significant change in superoxide radical generation, after thrombotic challenge, in mice neutrophils. The present study provides evidence for the involvement of free radicals in mice pulmonary thromboembolism.
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PMID:Effect of pulmonary thromboembolism on circulating neutrophils in mice. 132 50

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

We report the partition coefficients of lysozyme, chymotrypsinogen-A, albumin and catalase in sixty four Polyethyleneglycol/Dextran/Water systems at 4, 25 and 40 degrees C. We found that the partition coefficients of the four proteins generally increase with increasing temperature. The influence of temperature on the partition coefficient seems to be highly dependent on the kind of protein which is partitioned and on the total polymer concentration, but does not, in general, depend on the molecular weight of the polymers. The partition coefficients of small and hydrophilic proteins like lysozyme and chymotrypsinogen-A are only slightly affected by changes in temperature, while the partition coefficients of bigger and more hydrophobic proteins like albumin and catalase are strongly affected by changes in temperature. The results suggest the incorporation of attractive forces (possible electrostatic) into a model previously reported by us.
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PMID:Temperature dependence of the partition coefficient of proteins in aqueous two-phase systems. 136 76

A bovine intestinal bacterial isolate, identified as Enterococcus hirae, was found to produce a bacteriocin (designated hiraecin S) inhibitory to Listeria monocytogenes and other Listeria spp. Identification to species level was determined by comprehensive biochemical and morphological tests which were verified by DNA-DNA homology assays. The antimicrobial agent was inactivated by pronase and papain and was insensitive to catalase. The antimicrobial activity was not due to hydrogen peroxide or acid formation, nor was lysozyme or muramidase activity observed in cell-free bacteriocin preparations. Inhibition of selected gram-negative bacteria was not observed. Other enterococci were sensitive to the bacteriocin, and except for Listeria spp., no other gram-positive bacteria tested were inhibited.
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PMID:Production of bacteriocin inhibitory to Listeria species by Enterococcus hirae. 148 76


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