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 mechanism involved in the decreased numbers of several trans-membrane proteins such as sodium pump sites, sodium-lithium countertransport, sodium potassium cotransport proteins, proteins mediating the passive efflux of sodium and insulin receptors in erythrocytes from patients with hyperthyroidism is not known. The ATP-dependent proteolytic system which is involved in the loss of trans-membrane proteins during the maturation of the reticulocyte may be involved in the accelerated loss of these membrane proteins. Therefore, the effect of thyroid hormones on the ATP-dependent proteolytic activity of reticulocyte lysates was examined in this study. Reticulocytosis was induced in 14 guinea pigs by phenylhydrazine hydrochloride injections for 5 consecutive days followed by 2 days of rest. T3 (10 micrograms/100 g body weight) was injected into 7 animals on day 4 and day 6. Reticulocyte-rich blood was withdrawn on day 8. Oxygen consumption determined 24 hours after injection of T3 was 25% higher (p less than 0.01) and T3 treated animals had a 2.5 fold higher (p less than 0.01) weight loss than control animals. The ATP-dependent proteolytic activity measured in reticulocyte lysates using 125I labelled lysozyme was 3.6 fold higher in the T3 than in the control group of guinea pigs (p less than 0.01). We conclude that thyroid hormones induce the ATP-dependent proteolytic activity of reticulocyte lysates which may be responsible for the reduced number of several trans-membrane proteins found in erythrocytes from patients with hyperthyroidism.
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PMID:Induction of the ATP-dependent proteolytic system in guinea pig reticulocyte lysates by triiodothyronine. 194 42

Human neutrophils were incubated either with purified cell envelope lipopolysaccharides (LPS) of salmonella or with different concentrations of LPS combined with Intralipid. Incubation of neutrophils with LPS alone increased their oxidative metabolism with increased release of oxygen radicals as measured by the nitroblue tetrazolium (NBT) test and chemiluminescence response. The amount of lysozyme released by the cells also increased during incubation with LPS. However, when the neutrophils were incubated with LPS together with Intralipid, the LPS induced stimulation of the neutrophil NBT reduction, chemiluminescence and lysozyme release was significantly decreased. Intralipid might substitute for plasma high density lipoproteins (HDL), which are known to inhibit the LPS effects on the neutrophils in the acute stage of an infection with Gram-negative bacteria.
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PMID:Intralipid decreases the bacterial lipopolysaccharide induced release of oxygen radicals and lysozyme from human neutrophils. 195 32

Neutrophilic granulocytes were exposed to an atmosphere of nearly 100% oxygen (hyperoxia) for one hour. The nitroblue tetrazolium (NBT) reduction, reflecting oxygen radical release, was decreased both in resting and stimulated cells, but lysozyme release was unchanged. Short time exposure of patients to oxygen hypertension might therefore be beneficial as therapy, in conditions where reduced production of oxygen radicals is required. The NBT reduction of resting and stimulated neutrophils in an atmosphere of purified argon (hypoxia) was also considerably decreased, and the lysozyme release unchanged. This reflects the anaerobic conditions in abscesses, where the contribution of neutrophil oxygen metabolites to the killing of microorganism might be reduced.
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PMID:Significance of oxygen availability for release of oxygen free radicals and lysozyme by neutrophils. 196 35

The effect of adsorbed substances on the properties of the water in various hydrogel contact lens materials was examined by exposing contact lenses (Hydron Zero 4, B&L 70, DuraSoft 3, Vistamarc, and Acuvue) to an artificial tear solution for various periods up to 14 days. The only materials affected were the high-water/ionic lenses which adsorbed a large amount of protein, predominantly lysozyme. In the DuraSoft 3 lenses the equilibrium water content (EWC) dropped from 49% to 46% and the freezing water from 28% to 21%. Similar changes were seen with the Vistamarc lenses. After a 10-day exposure of the Acuvue lens to artificial tears, the EWC decreased from 53% to 47% and the amount of freezing water from 33% to 23%. The decrease in the permeability of water seen with these materials was consistent with the decrease of the freezing water, i.e., the water able to participate in diffusion. Since the content of freezing water determines the transport through hydrogels it can be expected that any lens characteristics that depend upon the amount of this portion of water would be affected by the presence of proteins inside the polymer matrix. We extrapolated that an absolute change of 10% in the amount of freezing water could lead to a decrease in oxygen permeability of as much as 7 Dk units. In view of this work more attention should be given to changes in the properties of lenses during wear, in particular, in the high-water/ionic lenses.
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PMID:Effect of proteins on water and transport properties of various hydrogel contact lens materials. 204 86

The effects of the Pseudomonas aeruginosa-derived pigments, pyocyanin and 1-hydroxyphenazine (1-hp), on membrane-associated oxidative metabolism and release of lysozomal enzymes by human neutrophils were investigated in vitro. Pyocyanin, but not 1-hp, increased the generation of superoxide and the rate and duration of oxygen uptake by activated neutrophils. Both agents increased the myeloperoxidase-mediated iodinating activity of neutrophils, which in the case of 1-hp was due to stimulation of the release of myeloperoxidase by activated neutrophils. 1-hp also increased the release of lysozyme by activated neutrophils. Pyocyanin caused only slight enhancement of the release of myeloperoxidase and lysozyme by stimulated neutrophils but was more potent with respect to the release of the specific granule marker, vitamin B12-binding protein. These data indicate the existence of diverse, proinflammatory interactions of pyocyanin and 1-hp with human phagocytes, which may intensify neutrophil-mediated tissue damage during P. aeruginosa infections.
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PMID:Proinflammatory interactions of pyocyanin and 1-hydroxyphenazine with human neutrophils in vitro. 186 50

We studied the effects of exogenous, purified phospholipase C (PLC) on neutrophil oxidative metabolism, lysosomal enzyme release and aggregation. We found that PLC inhibited O2- and H2O2 generation and oxygen consumption, but did not alter glucose oxidation via the hexose monophosphate shunt. In contrast, we found a striking stimulation of aggregation and release of the lysosomal enzymes lysozyme and beta-glucuronidase. In experiments designed to further characterize the mechanism of the PLC effect on membrane activation we studied the effect of PLC on intracellular calcium concentration [Ca2+]i and found that PLC did not interfere with the fMLP-mediated rise in [Ca2+]i, suggesting that its inhibitory effect on the respiratory burst does not involve inhibition of early signal transduction events. In addition, we found that PLC alone results in mobilization of intracellular Ca2+ stores, consistent with its stimulatory effect on aggregation and lysosomal enzyme release.
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PMID:Inhibition of polymorphonuclear leukocyte oxidative metabolism by exogenous phospholipase C. 216 37

Mobilization of circulating neutrophils toward an inflamed area involves adherence of the cells to the vascular endothelium and subsequent penetration through the endothelial cell layer without causing significant damage. To investigate the nature of a possible protective mechanism, granulocytes were incubated with the extracellular matrix (ECM) produced by cultured endothelial cells and tested for release of enzymes, chemoattractants, and free oxygen radicals. In the absence of exogenously added stimuli, the neutrophils adhered to the ECM but there was no detectable release of lysozyme, chemotactic activity, or production of O2-. In contrast, the cells readily released a heparan sulfate-degrading endoglycosidase (heparanase) to an extent comparable with that released in contact with polystyrene surfaces. Neutrophils treated with the calcium ionophore A23187 or with the peptide FMLP produced O2- to a much lesser degree when incubated in contact with ECM-coated surfaces than did those incubated in contact with uncoated polystyrene culture dishes. The ECM itself was devoid of superoxide dismutase activity. Stimulation with opsonized zymosan was not inhibited by the ECM. Experiments with isolated constituents of the ECM revealed that fibronectin but not collagen type IV or laminin could partially inhibit O2- production by Ca2+ ionophore-stimulated neutrophils. Treatment of the ECM with proteolytic enzymes, but not with heparanase, abolished its inhibitory effect on neutrophil activation. These results indicate that the subendothelial basement membrane has the capacity to inhibit release of potentially noxious agents excluding heparanase, suggesting a preferential involvement of this enzyme in neutrophil diapedesis.
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PMID:Selective inhibition of neutrophil activation by the subendothelial extracellular matrix: possible role in protection of the vessel wall during diapedesis. 216 83

The allergic mediator release inhibitor CI-949 [5-methoxy-3-(1- methylethoxy)-1-phenyl-N-1H-tetrazol-5-yl-1H-indole-2-carbox amide L-arginine salt] was evaluated for its effect on the activation of human eosinophils, macrophages, and neutrophils by the phagocytic stimulus serum-opsonized zymosan (SOZ). CI-949 inhibited the SOZ- stimulated respiratory burst of eosinophils, measured as the generation of superoxide anion, with an IC50 of 22.8 microM. At concentrations of 100 microM, CI-949 had no inhibitory effect against lysosomal enzyme release by these cells. At 100 microM, CI-949 had no inhibitory effect against release of eosinophil peroxidase while inhibiting release of the macrophage lysosomal enzyme N-acetyl-beta-D- glucosaminidase by only 11.7 percent. In contrast, CI-949 inhibited the release of the neutrophil primary granule enzyme myeloperoxidase inhibiting of 21.4 microM, while inhibiting release of lysozyme from lysosomal enzyme release from secondary granules with an IC50 of 99.3 microM. These results demonstrate that oxygen radical generation and lysosomal enzyme release by human eosinophils, macrophages and neutrophils are differentially regulated by CI-949. These results suggest that these inflammatory cells may have distinct stimulus-related coupling mechanisms.
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PMID:Differential regulation of the activation of human eosinophils, macrophages, and neutrophils: effect of the allergic mediator release inhibitor CI-949. 217 15

The effect of a variety of proteins and amino acids was investigated on oxygen free radical activity as assessed by copper/hydrogen peroxide induced benzoate hydroxylation as well as copper-catalysed ascorbate autoxidation. Serum albumins from a variety of species (human, bovine and dog) had both inhibitory and stimulatory effects depending on the molar copper to protein ratio; low ratios were inhibitory and high stimulatory. Some other proteins tested (lysozyme, soybean trypsin inhibitor and conalbumin) also had dual (inhibitory and stimulatory) effects, as did both histidine and polyhistidine, but all effects occurred at different molar ratios presumably dependent on the relative affinities for the copper ions. In contrast, metallothionein and caeruloplasmin, proteins specialised to bind copper in vivo had no stimulatory effects. In this paper we show that in addition to their fairly well documented inhibitory effects, under certain conditions some proteins also stimulate radical reactions. The possible role of this phenomenon in vivo is discussed.
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PMID:Stimulatory and inhibitory actions of proteins and amino acids on copper-catalysed free radical generation in the bulk phase. 228 96

Refinement of triclinic lysozyme by restrained least squares against the 2 A resolution X-ray data is described, beginning with the model from cycle 17 of the preceding paper [Hodsdon, Brown, Sieker & Jensen (1990). Acta Cryst. B46, 54-62]. After 20 refinement cycles, R stood at 0.172. Nevertheless, serious errors involving both main-chain and side-chain atoms still remained, requiring numerous model rebuilding sessions interleaved with refinement cycles. After 63 cycles R = 0.124 for the model which includes all protein atoms, 249 water oxygen sites and five nitrate ions. Although the overall B is relatively low, 10.5 A2, B's for atoms in the region of residues 101-103, toward the termini of some of the longer side chains, and in the region of the C terminus of the main chain exceed 20 A2, indicating relatively high atomic mobilities, disorder, or remaining errors in the model.
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PMID:Refinement of triclinic lysozyme: II. The method of stereochemically restrained least squares. 230 27


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