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 granulocytes of a patient with generalized pustular psoriasis (GPP) were found to have impaired ability to fix iodine after ingestion of yeast particles. Since hexose monophosphate shunt (HMS) activity was increased and the contents of 3 other lysosomal enzymes, beta-glucuronidase, N-acetyl-beta-glucosaminidase and lysozyme, were within normal range, the impaired iodination appeared to be due to a selective defect of myeloperoxidase (MPO) activity within the phagocytic cells. The deficient iodination was accompanied by a decreased intracellular killing of E. coli and C. albicans. Since hexose monophosphate shunt activity was enhanced and azide and cyanide inhibited the intracellular killing of E. coli only moderately, the patient's granulocytes may possess azide- and cyanide-resistant, MPO-independant microbicidal systems coupled to the oxidative metabolism. Assessment of granulocyte iodination and enzyme contents of the relatives of the patient revealed no hereditary transmission. Since GPP is characterized by the development of subcorneal pustules containing granulocytes, the MPO-deficiency may be the cause of or enhance the development of the disease.
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PMID:Function of granulocytes with deficient myeloperoxidase-mediated iodination in a patient with generalized pustular psoriasis. 17 20

Host responses to infectious organisms should be modulated so that tissue-damaging products of inflammatory cells do not produce excessive destruction of normal tissue. Lysozyme, which is continuously secreted by monocytes, which, in turn, migrate relatively late to inflammatory areas, was found to significantly dampen several responses of neutrophils to inflammatory stimulants. Thus, human lysozyme obtained and purified from the urine of patients with monocytic leukemia (but not its structurally similar and comparably cationic analogue, eggwhite lysozyme) depresses chemotaxis of normal neutrophils to activated complement, bacterial supernate, and N-formylmethionyl-phenylalanine. In addition, human (but not eggwhite) lysozyme depresses oxidative metabolism (hexose monophosphate shunt activity) and superoxide generation of neutrophils. The specificity of the suppressive effects was indicated by inhibition studies with rabbit antihuman lysozyme antibody, and with the trisaccharide of N-acetylglucosamine, a specific inhibitor of lysozyme. The results suggest that lysozyme, a product of inflammatory cells themselves, may function in a negative feedback system to modulate the inflammatory response.
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PMID:Modulation of neutrophil function by lysozyme. Potential negative feedback system of inflammation. 22 43

The role of ascorbic acid is reviewed with regard to antimicrobial activity, interferon production, and humoral and cellular immune responses. Ascorbic acid appears to play a role in a number of neutrophil functions including increased chemotaxis, increased particulate ingestion, enhanced lysozyme-mediated non-oxidative killing, protection against the toxic effects of superoxide anion radical, inhibition of the halide-peroxide-myeloperoxidase system without a pronounced bactericidal effect, and stimulation of the hexose monophosphate shunt.
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PMID:Ascorbic acid, neutrophil function, and the immune response. 35 20

Polymorphonuclear neutrophils were simultaneously collected from dogs by continuous-flow centrifugation and continuous-flow filtration leukapheresis. In vitro studies were performed on cells obtained by the two methods as well as on control cells. Studies consisted of assessment of phagocytic capacity, degranulation, chemotaxis, hexose monophosphate (HMP) shunt activity, and bacterial killing. The cells obtained from the filter were metabolically more active than those harvested by centrifugation, as evidenced by increase in resting HMP shunt activity and dimunition in total available lysozyme-secreting activity compared to centrifuged cells. Despite their impaired phagocytic capacities, the filtered cells were able to kill Staphylococcus aureus as efficiently as the centrifuged cells. Both cell populations responded to chemotactic gradients equally.
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PMID:In vitro functional capabilities of canine polymorphonuclear neutrophils collected simultaneously by continuous-flow centrifugation and continuous-flow filtration leukopheresis. 71 86

The crystal structure of the complex between neuraminidase from influenza virus (subtype N9 and isolated from an avian source) and the antigen-binding fragment (Fab) of monoclonal antibody NC41 has been refined by both least-squares and simulated annealing methods to an R-factor of 0.191 using 31,846 diffraction data in the resolution range 8.0 to 2.5 A. The resulting model has a root-mean-square deviation from ideal bond-length of 0.016 A. One fourth of the tetrameric complex comprises the crystallographic model, which has 6577 non-hydrogen atoms and consists of 389 protein residues and eight carbohydrate residues in the neuraminidase, 214 residues in the Fab light chain, and 221 residues in the heavy chain. One putative Ca ion buried in the neuraminidase, and 73 water molecules, are also included. A remarkable shape complementarity exists between the interacting surfaces of the antigen and the antibody, although the packing density of atoms at the interface is somewhat looser than in the interior of a protein. Similarly, there is a high degree of chemical complementarity between the antigen and antibody, mediated by one buried salt-link, two solvated salt-links and 12 hydrogen bonds. The antibody-binding site on neuraminidase is discontinuous and comprises five chain segments and 19 residues in contact, whilst 33 neuraminidase residues in eight segments have 899 A2 of surface area buried by the interaction (to a 1.7 A probe), including two hexose units. Seventeen residues in NC41 Fab lying in five of the six complementarity determining regions (CDRs) make contact with the neuraminidase and 36 antibody residues in seven segments have 916 A2 of buried surface area. The interface is more extensive than those of the three lysozyme-Fab complexes whose crystal structures have been determined, as judged by buried surface area and numbers of contact residues. There are only small differences (less than 1.5 A) between the complexed and uncomplexed neuraminidase structures and, at this resolution and accuracy, those differences are not unequivocal. The main-chain conformations of five of the CDRs follow the predicted canonical structures. The interface between the variable domains of the light and heavy chains is not as extensive as in other Fabs, due to less CDR-CDR interaction in NC41. The first CDR on the NC41 Fab light chain is positioned so that it could sterically hinder the approach of small as well as large substrates to the neuraminidase active-site pocket, suggesting a possible mechanism for the observed inhibition of enzyme activity by the antibody.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Refined crystal structure of the influenza virus N9 neuraminidase-NC41 Fab complex. 138 57

Bombesin, gastrin-related peptide (GRP), and related peptides sharing the common carboxyterminal sequence stimulate lactoferrin (serous cell marker) and glycoconjugate (mucous cell and goblet cell marker) release from human nasal mucosal explants in vitro. In vivo, GRP released from trigeminal sensory nerves may act upon GRP-bombesin binding sites on respiratory epithelial cells and submucosal glands. To determine whether GRP-bombesin can stimulate nasal secretion in vivo, bombesin was administered to eight normal subjects by unilateral, topical administration. Secretions from both nostrils were collected for measurement of total protein, lysozyme, hexose-containing glycoconjugates, and albumin (marker of vascular permeability). Baseline secretions contained 72.0 +/- 17.3 micrograms/ml of total protein, 14 +/- 2 micrograms/ml of lysozyme, 113 +/- 44 micrograms/ml of hexose-containing glycoconjugates, and 7.8 +/- 3.4 micrograms/ml of albumin. Hexose-containing glycoconjugate secretion was significantly increased after 1 nmol (385 +/- 63 micrograms/ml, P less than 0.001 by analysis of variance), 10, 100, and 1,000 nmol of bombesin, but the secretion was not dose dependent. Significant lysozyme (24 +/- 3 micrograms/ml, P less than 0.05) and total protein (155 +/- 23 micrograms/ml, P less than 0.01) secretion occurred after 1,000 nmol. No statistically significant changes in albumin secretion occurred at any dose. Saline had no significant effects on secretion. Therefore, bombesin stimulated secretion from submucosal glands and possibly epithelial cells in the human nose without affecting vascular permeability.
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PMID:Bombesin stimulates human nasal mucous and serous cell secretion in vivo. 173 81

Competitive hormone binding studies with membrane and partially purified receptors from Xenopus laevis oocytes revealed that the oocyte possesses high affinity (KD = 1-3 nM) binding sites for both insulin growth factors 1 and 2 (IGF-1 and IGF-2), but not for insulin. Consistent with these findings, IGF-1 activates hexose uptake by Xenopus oocytes with a KA (3 nM) identical with its KD, while IGF-2 and insulin activate hexose uptake with KA values of 50 nM and 200-250 nM, respectively, suggesting activation mediated through an IGF-1 receptor. Both IGF-1 and insulin activate receptor beta-subunit autophosphorylation and, thereby, protein substrate (reduced and carboxyamidomethylated lysozyme, i.e. RCAM-lysozyme) phosphorylation with KA values comparable to their respective KD values for ligand binding and KA values for activation of hexose uptake. The autophosphorylated beta-subunit(s) of the receptor were resolved into two discrete components, beta 1 and beta 2 (108 kDa and 94 kDa, respectively), which were phosphorylated exclusively on tyrosine and which exhibited similar extents of IGF-1-activated autophosphorylation. When added prior to autophosphorylation, RCAM-lysozyme blocks IGF-1-activated autophosphorylation and, thereby, IGF-1-activated protein substrate (RCAM-lysozyme) phosphorylation. Based on these findings, we conclude that IGF-1-stimulated autophosphorylation of its receptor is a prerequisite for catalysis of protein substrate phosphorylation by the receptor's tyrosine-specific protein kinase. The IGF-1 receptor kinase is implicated in signal transmission from the receptor, since anti-tyrosine kinase domain antibody blocks IGF-1-stimulated kinase activity in vitro and, when microinjected into intact oocytes, prevents IGF-1-stimulated hexose uptake.
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PMID:The insulin-like growth factor 1 (IGF-1) receptor is responsible for mediating the effects of insulin, IGF-1, and IGF-2 in Xenopus laevis oocytes. 185 44

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

This study examined the effects of a 25-kilodalton (kDa) glycolipoprotein derived from Mycobacterium tuberculosis on phagocyte functions associated with antimicrobial activity. The 25-kDa fraction inhibited the ability of both polymorphonuclear cells and cultured monocytes to release lysozyme and produce hydrogen peroxide. In addition, the glycolipoprotein was capable of reducing hexose monophosphate shunt activity and interfered with the ability of polymorphonuclear cells to reduce Nitro Blue Tetrazolium. Inhibition of these antimicrobial systems was optimal at a 50-micrograms/ml concentration of the 25-kDa fraction. Gamma interferon, but not alpha interferon, partially reversed the inhibitory effect of the mycobacterial component in all of the systems assessed. These studies indicate important mechanisms in the understanding of the pathogenesis of tuberculosis and suggest that gamma interferon may have a therapeutic role in mycobacterial diseases.
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PMID:A 25-kilodalton fraction from Mycobacterium tuberculosis that inhibits hexose monophosphate shunt activity, lysozyme release, and H2O2 production: reversal by gamma interferon. 249 74

Amphotericin B and some of the imidazole drugs have been shown to suppress certain neutrophil and lymphocyte functions both in vitro and in vivo. We present here the in vitro effects of: amorolfin, a morpholine derivative; the imidazoles clotrimazole and ketoconazole; the N-substituted imidazole bifonazole and a triazole (ICE 195, 739), on neutrophil and lymphocyte function. All of these drugs inhibited neutrophil random migration, chemotaxis and hexose monophosphate shunt activity. The effects of the drugs on neutrophil adherence, deoxyglucose transport and beta-glucuronidase release were variable while lysozyme release was unaffected. Natural Killer cell cytoxicity was depressed by all drugs tested except for amorolfin. Mitogen-induced lymphocyte blastogenesis was suppressed by all the antifungal drugs tested. Similar results were obtained using the mitogens phytohaemagglutinin, concanavalin A and pokeweed mitogen. The mechanism of action of these drugs on these cell functions remains unknown, there may be a correlation between their effects on fungi and their effects on leukocytes. Clearance of systemic fungal infection is heavily dependent on integrity of the cellular immune system and it is clearly undesirable that antifungal drugs have immunosuppressive properties. Further studies are required to determine the in vivo and clinical relevance of our observations.
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PMID:Effects of the newer antifungal agents (bifonazole, ICI 195, 739 and amorolfin) on in vitro phagocytic, lymphocytic and natural-killer cell responses. 259 17


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