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 action of the tumor promoter, phorbol 12,13-dibutyrate (PDBu), on rabbit peritoneal and human neutrophils is associated with stimulation of 14C-arachidonic acid incorporation into phospholipids within 1-2 min. Stimulated 14C-arachidonate incorporation was relatively selective for phosphatidylinositol (PI) in rabbit neutrophils. In contrast, the secretory response of human neutrophils to PDBu coincided with stimulated label incorporation into phosphatidylserine (PS), phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidic acid (PA) and PI. Significant increases in label incorporation were observed with PDBu concentrations as low as 2 nM, and the dose response of stimulated label incorporation paralleled that of evoked lysozyme secretion. A parallel, but partial, inhibition of PDBu-stimulated PI labeling and enzyme release was observed after exposing rabbit neutrophils to calcium-deprived medium, whereas calcium deprivation failed to significantly depress either of these stimulant actions of PDBu in human neutrophils. Further, in rabbit neutrophils PDBu elicited an increase in cell associated 45Ca. However, PDBu was unable to promote the incorporation of 32P orthophosphate into PI or enhance phospholipase A2 activity in broken cells. These findings suggest that one expression of the interaction between phorbol esters and their receptors on neutrophils involves the turnover of arachidonic acid in phospholipids. This stimulated turnover of arachidonate may be a critical step in the cascade of events associated with neutrophil activation.
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PMID:Regulation of phosphatidylinositol turnover, calcium metabolism and enzyme secretion by phorbol dibutyrate in neutrophils. 642 67

Cationic lysosomal proteins from human polymorphonuclears (PMN) were isolated by column chromatography and divided into five fractions. On acrylamide gel electrophoresis, fraction I had four bands slower than lysozyme (LZM) mobility; fraction II had five or six bands slower than LZM; fraction III had at least seven bands slower and two bands faster than LZM; fraction IV contained LZM, two bands faster and a few faint bands slower than LZM; fraction V was composed of almost pure LZM. Partial characterization of the fractions showed presence of neutral protease in fractions I-IV, chymotrypsin in fraction III, lysozyme in fractions IV and V, and phospholipase A2 mainly in fractions II and III. Modulatory activity of fractions I-V were tested at concentrations up to 50 micrograms/ml. Enhancement of phagocytosis of Staphylococcus aureus was observed by fractions I, IV, and V, whereas phagocytic index was enhanced by all but the fraction II. Intracellular bactericidal activity (ICBA) was markedly enhanced by fractions I, II, and V. Addition of DNA or cytochalasine B inhibited or abolished phagocytosis-enhancing activity of cationic fractions. Their influence on ICBA was much less pronounced. Fraction III enhanced phagocytic index and phagocytosis of E. coli, whereas fractions I and II enhanced intracellular bactericidal activity against this bacteria. Enhancement of phagocytic activity of monocytes has also been observed. The data suggest that some cationic lysosomal fractions from human PMNs enhance phagocytosis and phagocytic index by human PMNs and monocytes and intracellular bactericidal activity of human PMNs. This alternative pathway of phagocytic enhancement is unrelated to the previously described enhancers of phagocytosis and may play a role in defense mechanisms against infection.
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PMID:Modulation of phagocytosis and intracellular bactericidal activity of polymorphonuclear and mononuclear cells by cationic proteins from human granulocytes: alternative pathway of phagocytic enhancement. 651 76

We have studied the role of arachidonic acid (AA) metabolism in the release of lysosomal enzymes (beta-glucuronidase and lysozyme) from human polymorphonuclear leukocytes (PMNs). 5,8,11,14-Eicosatetraenoic acid (ETYA), which inhibits both the cyclo-oxygenase and the lipoxygenase pathways of AA metabolism, was found to cause a dose-dependent inhibition of lysosomal enzyme release from human PMNs induced by immunological (i.e., serum-treated zymosan: Zx) and nonimmunological stimuli (i.e., formyl methionine-containing peptide and the Ca2+ ionophore A23187). In contrast, the non-steroidal anti-inflammatory drugs (indomethacin, meclofenamic acid and aspirin), which only block the cyclo-oxygenase pathway of AA metabolism, had little effect on enzyme release from PMNs induced by the same stimuli. 5,8,11-Eicosatriynoic acid (ETI), a selective inhibitor of the lipoxygenase pathway of AA metabolism, caused a dose-dependent inhibition of lysosomal enzyme release elicited by Zx, f-met peptide, and A23187. p-Bromophenacyl bromide (BPB), which inhibits the phospholipase A2 (PLA2) activity in several tissues, was found to cause a dose-dependent inhibition of lysosomal enzyme release induced by the same immunological and non-immunological stimuli. The inhibitory effect of BPB on enzyme release was irreversible and extremely rapid. It appears that activation of PLA2 and the products of the AA metabolism, generated via a lipoxygenase pathway, play an essential role in the biochemical control of human PMNs activation and secretion.
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PMID:Possible role of arachidonic acid and of phospholipase A2 in the control of lysosomal enzyme release from human polymorphonuclear leukocytes. 664 91

1. The outer membrane of a phospholipase A-deficient mutant of Escherichia coli K12, isolated without the use of EDTA and lysozyme, showed the same freeze-fracture morphology as that seen in cells and remained stable for hours as observed by 31P-NMR. 2. 31P-NMR spectroscopy of the isolated outer membranes revealed that the lipopolysaccharide exists in the same physical state as in phospholipid-lipopolysaccharide liposomes and is most probably arranged in a bilayer at 37 degrees C. The outer membrane contains most or all of the phospholipids at 37 degrees C, and all the phospholipids at 20 degrees C, as a bilayer. 3. The 31P-NMR spectroscopy of the outer membranes from a mutant strain lacking the major outer membrane protein b, c and d (60% of the total outer membrane protein) yields virtually the same spectrum as the wild-type outer membranes, although most of the particles and pits which were observed in wild-type outer membranes in freeze-fracture electron microscopy were absent. 4. Whereas treatment of wild-type outer membranes with calcium ions has no effect on the 31P-NMR spectrum, treatment with EDTA results in more motion of the lipopolysaccharide.
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PMID:31P nuclear magnetic resonance and freeze-fracture electron microscopy studies on Escherichia coli. III. The outer membrane. 676 82

Polymyxin-resistant pmrA mutants of Salmonella typhimurium differed from their parents in that they were resistant to tris(hydroxymethyl)aminomethane-ethylenediaminetetraacetate-lysozyme, tris(hydroxymethyl)aminomethane-ethylenediaminetetraacetate-deoxycholate, and tris(hydroxymethyl)aminomethane-ethylenediaminetetraacetate-bacitracin. Tris(hydroxymethyl)aminomethane-ethylenediaminetetraacetate released about 50% less lipopolysaccharide from the pmrA strains than from the parental strains when the bacteria were grown in L-broth containing 2 mM Ca2+. Protamine, polylysine, octapeptin, benzalkonium chloride, cold NaCl, cold MgCl2, or cold tris(hydroxymethyl)aminomethane hydrochloride (pH 7.2) caused no leakage or markedly less leakage of periplasmic beta-lactamase from a pmrA mutant than from its parent strain. pmrA mutants were more resistant than their parent strains to protamine and polylysine but not to octapeptin or benzalkonium chloride, as measured by the ability of these agents to kill the bacteria or to sensitize them to deoxycholate-induced lysis. The pmrA strains did not differ from their parent strains in sensitivity to several antibiotics, in porin function (as measured by cephaloridine diffusion across the outer membrane), or in outer membrane-associated phospholipase A activity.
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PMID:Increased outer membrane resistance to ethylenediaminetetraacetate and cations in novel lipid A mutants. 679 77

The aim of the present study was to investigate the pathways of platelet-activating factor (PAF) production and release from human monocytes. For this purpose, both phagocytic stimuli and stimuli induced by soluble agents were used. The phagocytic stimuli exerted their effect in a receptor-specific mechanism related to surface Fc, C3b and C3d receptors. Stimuli induced by soluble agents, such as A23187 and pH 10.6, which do not require interaction with specific receptors, were also effective in inducing PAF release. In contrast, C5a, a soluble agent which induces a receptor-mediated release of PAF from neutrophils, failed to induce PAF release from monocytes. PAF release from monocytes could be dissociated from phagocytosis and from release of lysozyme. The PAF release required the presence of extracellular cations, the activation of membrane esterase and phospholipase A2 and the integrity of the microfilament system. Moreover, PAF release was modulated by lipoxygenase and intracellular cAMP levels. The relevance of an acetylation process in the biosynthesis of PAF was suggested by the increase of PAF yields in the presence of sodium acetate and by the incorporation of 14C-sodium acetate into molecules of active PAF.
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PMID:Biosynthesis and release of platelet-activating factor from human monocytes. 682 35

The topography of phospholipids in the photosynthetic membranes of Rhodopseudomonas sphaeroides was investigated by using purified chromatophores and spheroplast-derived vesicles (SDVs). Chromatophores are closed vesicles oriented inside out with respect to the cytoplasmic membrane (cytoplasmic side out) and obtained from French-pressed cell lysates. SDVs are oriented right side out (periplasmic side out) and are obtained after osmotic lysis of lysozyme-treated cells. Phosphatidylethanolamine (PE) comprised approximately 62% and phosphatidylglycerol (PG) comprised approximately 33% of the total phospholipid of both vesicle preparations. The relatively membrane impermeable reagent trinitrobenzenesulfonate (TNBS) at 3 mM concentration and 5 degrees C modified chromatophore and SDV PE with kinetics indicating the occurrence of fast- and slow-reacting pools of PE. The fast-reacting pools comprised 33% and 55% of the total PE of chromatophores and SDVs, respectively. The slow-reacting pools comprised 61% and 32% of the total PE of chromatophores and SDVs, respectively. Phospholipase A2 treatment of chromatophores (1 unit/mg of vesicle protein) for 1 h at 37 degrees C resulted in hydrolysis of 73% and 77% of the total PG and PE, respectively. Similar enzyme treatment of SDVs resulted in 14% and 60% hydrolysis of the total PG and PE, respectively. Phospholipase A2 treatment inhibited 60% of the succinate dehydrogenase activity of chromatophores but only 8% of the activity of SDVs, indicating the membrane impermeability of phospholipase A2. Incubation of chromatophores for 10 min with 3 mM TNBS at 5 degrees C and then treatment with phospholipase A2 for 10 min and 1 h resulted in the hydrolysis of 10% and 61%, respectively, of unmodified PE. The results indicate asymmetric distributions of PE polar head groups (32-33% cytoplasmic side, 55-61% periplasmic side) and PG (73% cytoplasmic side, 14% periplasmic side) across the membrane. Also, a rapid and unidirectional transbilayer movement of PE polar head groups from the periplasmic to cytoplasmic surfaces of the membrane appears to occur during phospholipase A2 hydrolysis on the chromatophore surfaces.
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PMID:Phospholipid topography of the photosynthetic membrane of Rhodopseudomonas sphaeroides. 697 21

1. Peritoneal neutrophil leucocytes, derived from the rabbit, release phospholipase A (EC 3.1.1.4) activity during phagocytosis of complement-coated zymosan particles, or during treatment with Ca2+. This enzyme is able to release [1-14C]oleate from the membrane phospholipids of Escherichia coli. 2. The release of phospholipase A paralleled that of the known lysosomal marker enzymes beta-glucuronidase and lysozyme. The phospholipase A would thus appear to be derived from the lysosomal granules of the cells. 3. The released enzyme is of A2 specificity, has an absolute requirement for divalent cations, and is active over a broad pH range (pH 6-9).
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PMID:Phospholipase A2 activity of lysosomal origin secreted by polymorphonuclear leucocytes during phagocytosis or on treatment with calcium. 729 51

The binding of the apolar fluorescent dye 8-anilinonaphthalene-1-sulfonate (ANS) to bovine serum albumin (BSA), phospholipase A2 (PLA2), ovalbumin, lysozyme, cobrotoxin and N-acetyltryptophanamide was used to assess the factors affecting the efficiency of energy transfer from Trp residues to the ANS molecule. We found that the efficiency of energy transfer from Trp residues to ANS was associated with the ability of proteins to enhance the ANS fluorescence. At the same molar concentration of protein, BSA enhanced ANS fluorescence most among these proteins; its Trp fluorescence was drastically quenched by the addition of ANS. Fluorescence enhancement of ANS in PLA2-ANS complex increased upon addition of Ca2+ or change of the buffer to acidic pH, resulting in a higher efficiency of energy transfer from Trp residues to ANS. There was limited ANS fluorescence enhancement with ovalbumin, lysozyme, cobrotoxin, and N-acetyltryptophanamide and a less efficient quenching in Trp fluorescence. The capabilities of proteins for binding with ANS correlated with the decrease in their Trp fluorescence being quenching by ANS. However, the microenvironment surrounding Trp residues of proteins did not affect the energy transfer. Based on these results, the factors that affected the energy transfer from Trp residues to ANS are discussed.
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PMID:Energy transfer from tryptophan residues of proteins to 8-anilinonaphthalene-1-sulfonate. 770 45

Protein crystal growth is quite important for the determination of protein structures which are essential to the understanding of life at molecular level as well as to the development of molecular biotechnology. The microgravity environment of space is an ideal place to study the complicated protein crystallization and to grow good-quality protein crystals. A number of crystal-growth experiments of 10 different proteins were carried out in August, 1992 on the Chinese re-entry satellite FSW-2 in space using a tube crystallization equipment made in China. A total of 25 samples from 6 proteins produced crystals, and the effects of microgravity on protein crystal growth were observed, especially for an acidic phospholipase A2 and henegg-white lysozyme which gave better crystals in space than earth-grown crystals in ground control experiments. The results have shown that the microgravity in space favors the improvement of the size, perfection, morphology and internal order of the grown protein crystals.
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PMID:Protein crystal growth in microgravity. 786 21


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