Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.17 (lysozyme)
 21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Three human lysozymes containing a mutation either at Asp-53 to Glu or at Tyr-63 to Trp or Phe were synthesized and examined for their immunological and enzymatical activities in comparison with the native one. All mutants were immunologically indistinguishable from native human lysozyme. The [Trp63] and [Phe63] mutants catalysed the hydrolysis of Micrococcus lysodeikticus cell wall and glycol chitin effectively, while the [Glu53] mutant displayed very low activity toward M. lysodeikticus cells and no detectable activity toward glycol chitin.
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PMID:Engineering of the active site of human lysozyme: conversion of aspartic acid 53 to glutamic acid and tyrosine 63 to tryptophan or phenylalanine. 288 Jun 6

Circular dichroism studies on synthetic peptides corresponding to the signal sequences of chicken lysozyme and Escherichia coli proteins, lambda-receptor and lipoprotein, have been carried out in trifluoroethanol. The peptides, (CH3)3-C-O-CO-Thr-Leu-Lys-Lys-Leu-Pro-Leu-Ala-Val-Ala-Val-Ala-Ala-Gly- Val-Met-Thr-Ala- Ala-Met-Ala-OCH3, (CH3)3-C-O-CO-Met-Lys-Ser-Leu-Leu-Ile-Leu-Val-Leu-Cys(benzyl)- Phe-Leu-Pro- Leu-Ala-Ala-Leu-Gly-OH and (CH3)3-C-O-CO-Leu-Val-Leu-Gly-Ala-Val-Ile-Leu-Gly- Thr-Thr-Leu-Leu- Ala-Gly-OCH3, corresponding to the signal sequences of lambda-receptor, lysozyme and the hydrophobic region of lipoprotein, respectively, show two negative bands at approx. 205 and 220 nm, characteristic of an alpha-helical conformation. Secondary structural features are discernible even in the shorter, 12-residue carboxy-terminal fragments of these signal peptides. A comparison of the conformation of the amino-terminal, central and carboxy-terminal fragments of lipoprotein signal sequence indicates that the central octapeptide fragment is more structurally ordered compared to the amino- and carboxy-terminal fragments.
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PMID:Circular dichroism studies on synthetic signal peptides. 293 58

The immunological reactivity against the N-terminal region of hen egg-white lysozyme (HEL) has been investigated by a synthetic peptide (PHEL) comprising residue 1-18 of HEL and by an analogue peptide (PREL) in which phenylalanine at position 3 is substituted by tyrosine. Both peptides are immunogenic in (C57BL/10 X DBA/2)F1 mice genetically responder to HEL. In C57BL/6 mice, genetically nonresponder to HEL, PREL induces anti-peptide antibodies that also bind to PHEL whereas PHEL is not immunogenic. Thus, a single amino acid substitution in a synthetic peptide converts a nonresponder mouse strain into a responder one. Anti-PHEL antibodies demonstrate a higher binding to HEL than anti-PREL antibodies, indicating that phenylalanine at position 3 is important for induction of anti-peptide antibodies able to recognize native HEL. At the T cell level the two peptides show very high bidirectional cross-reactivity between themselves and with HEL for interleukin 2 production, antigen-specific proliferation and delayed-type hypersensitivity response, whereas conservation of phenylalanine at position 3 is required for induction of suppressor cells cross-reactive with HEL. This indicates that the N-terminal region of HEL contains epitope(s) able to induce the same level of helper T cell activity as the native HEL molecule. However, helper T cells do not discriminate between PHEL and PREL whereas phenylalanine at position 3 is critical for HEL-specific suppressor T cell induction.
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PMID:Analysis of lysozyme-specific immune responses by synthetic peptides. I. Characterization of antibody and T cell-mediated responses to the N-terminal peptide of hen egg-white lysozyme. 293 8

Activated human polymorphonuclear leukocytes (PMN) isolated from peripheral blood specifically bind 125I-laminin after stimulation with phorbol 12-myristate 13-acetate (PMA) or f-Met-Leu-Phe (FMLP) at 37 degrees C. Changes in laminin receptor expression are stimulus dose dependent at both chemotactic (10(-10) M to 10(-6) M) concentrations of FMLP, and secretory (greater than 5 ng/ml) levels of PMA. In the presence of cytochalasin B (5 micrograms/ml), 10(-7) M FMLP activation stimulates specific laminin binding, with an apparent Kd = 3.9 X 10(-9) M and 6.47 X 10(5) binding sites/cell, reaching equilibrium within 10 min at 4 degrees C. This observed activation-dependent change in laminin receptor expression is not due to interference by endogenous laminin, because no fluorescein-visualized anti-laminin antibody bound to cells without added glycoprotein, regardless of the level of activation. Levels of neutrophil lysozyme release, which show a PMA dose dependence similar to that of receptor binding activity, suggest that granule-plasma membrane fusion may be significant during increases in receptor expression. A lack of receptor stimulation by PMA from a granule-deficient patient or in granule-depleted cytoplasts from normal donors additionally supports this hypothesis. Electroblot transfer and autoradiography of subcellular fractions from unstimulated PMN reveals the presence of a 68,000 dalton laminin-binding component in the secondary/tertiary granule (beta) fraction, which may represent an intracellular laminin receptor pool.
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PMID:Human neutrophil laminin receptors: activation-dependent receptor expression. 294 78

Two mouse monoclonal antibodies, L12.2 and S5.22, were developed that are specific for human neutrophilic granulocytes and produce a twofold to threefold stimulation of n-formyl-methionine-leucyl-phenylalanine (FMLP)-induced chemotaxis. Stimulation of chemotaxis by the antibodies is specific for FMLP and is concentration dependent. L12.2 appears to be more potent in stimulating chemotaxis and is isotypically distinct from S5.22. In addition, although L12.2 reacts only with mature peripheral blood granulocytes, S5.22 reacts with leukemic cells of both myeloid and monocytic origin and with immature granulocyte precursor cells. This suggests that L12.2 interacts with an antigen that appears late in the differentiation pathway, whereas S5.22 binds to an antigen that is present throughout the myeloid lineage. By means of the under-agarose and Boyden chamber techniques, L12.2, but not S5.22, by itself was also found to be a potent granulocyte chemoattractant. Cells in a gradient of L12.2 display polarized and oriented morphology. L12.2 alone, but not S5.22, also stimulates granulocyte phagocytosis and induces superoxide anion production. Neither L12.2 nor S5.22 affected the release of myeloperoxidase or lysozyme from granulocytes either alone or in combination with FMLP, C5a, or the tumor promoter, 12-O-tetradecanoyl-phorbol-13-acetate (TPA). These results suggest that L12.2 interacts with a single antigenic determinant on granulocytes that is involved in chemotaxis, phagocytosis, and superoxide anion release.
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PMID:Stimulation of human neutrophilic granulocyte chemotaxis by monoclonal antibodies. 298 Dec 60

Neutrophil superoxide production has been recognized as an important pathway for microbicidal activity and regulation of the local inflammatory environment. To investigate neutrophil superoxide production in sepsis, we studied 22 patients with intra-abdominal infections, and correlated superoxide production with chemotactic response and granular enzyme content. Our results showed that neutrophils from infected patients had specific loss of chemotactic response to C5a, and were deficient in the granular enzymes, lysozyme, and beta-glucuronidase. Superoxide production in response to opsonized zymosan was intact, but response to the chemoattractant N-formyl-methionyl-leucyl-phenylalanine was markedly depressed. This could be reversed in vitro by the addition of cytochalasin B. These results suggest that down regulation of exocytosis of superoxide to nonphagocytic stimuli occurs during sepsis, possibly protecting the host from tissue injury due to oxide radical release. Superoxide response to phagocytic stimulation was intact.
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PMID:Regulation of neutrophil superoxide production in sepsis. 298 24

Myeloperoxidase (MPO)-deficient neutrophils (PMN) released considerably more beta-glucuronidase, lysozyme and vitamin B12-binding activities, when exposed to opsonized zymosan (STZ), than the normal counterpart. Release of the soluble enzyme lactate dehydrogenase was not appreciably changed over the incubation time with particles in either cell type. MPO-deficient PMN and normal PMN ingested STZ particles at a similar rate at early times, but thereafter phagocytosis by MPO-deficient PMN was significantly higher than that by normal PMN. The difference in degranulation between the two cell types greatly exceeded the difference in ingestion and was evident already at early phagocytosis times when no difference in phagocytosis was observed; this suggested that the higher degranulation in MPO-deficient PMN was at least in part independent of the increased ingestion. This was confirmed by experiments with the soluble stimulant N-formyl-L-norleucyl-L-leucyl-phenylalanine (FNLLP). MPO-deficient PMN and normal PMN exhibited a comparable respiratory burst when exposed to FNLLP plus cytochalasin B, but the defective cells released more azurophilic and specific granule markers than normal PMN. These results indicate that MPO-deficient PMN degranulate more than normal PMN and suggest a role for MPO in the regulation of degranulation.
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PMID:Increased degranulation of human myeloperoxidase-deficient polymorphonuclear leucocytes. 298 89

The ability of pepstatin A, a protease inhibitor produced by Streptomyces testaceus, to elicit a number of responses by the human PMN has been studied. In lysozyme and beta-glucuronidase release, pepstatin A 10(-5)M is equivalent to the synthetic oligopeptide N-formyl-methionyl-leucyl-phenylalanine (FMLP) 10(-7)M. In superoxide release, pepstatin A 10(-5)M produces 80% of that originated by FMLP 10(-7). After two minutes of incubation the superoxide release is important, there being no further increase after 10 minutes. Preincubation of the cells with cytochalasin B before stimulation with pepstatin A elicits a noticeable increase in O2- release. In chemotaxis, pepstatin A 10(-6) originates the same cell motility as FMLP 10(-9). Pepstatin A produces a cross deactivation with FMLP which adds further evidence to the hypothesis that both stimuli compete for the same receptor in the PMN.
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PMID:[Effects of pepstatin A on neutrophils; cross-deactivation with FMLP]. 298 85

Like in the polymorphonuclear leukocyte (PMN), the platelet-derived growth factor (PDGF) purified to homogeneity is capable of inducing monocyte activation responses as evaluated by generation of superoxide anion (O-.2) from membrane-associated oxidase system, release of granule enzymes, and enhanced cell adherence and cell aggregation. Superoxide anion release was maximized at 10 ng/mL PDGF and was comparable to that induced by 10(-7) mol/L formyl-methionyl-leucyl-phenylalanine. The potency of PDGF to induce this response in monocytes was of the same magnitude as that observed in PMNs. Similarly, lysozyme release and monocyte adherence were also increased in a dose-dependent manner and achieved maximal responses at 40 ng/mL concentration of PDGF. The PDGF concentration required to achieve maximal monocyte aggregation was two-fold (60 ng/mL) of that found for PMNs. In contrast to PMNs, a positive correlation (gamma = .93; P less than .01) was observed between the increases of PDGF concentration and beta-glucuronidase release. These findings indicate that PDGF can induce the full sequence of cell activation events in human monocytes similar to human PMNs.
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PMID:Platelet-derived growth factor promotes human peripheral monocyte activation. 298 67

Human neutrophils treated with pertussis toxin had decreased functional responses to several agents including zymosan-treated serum, heat-aggregated immunoglobulin, platelet-activating factor, and fMet-Leu-Phe. Responses affected include superoxide generation and release of lysozyme. The degree and type of inhibition was dependent on the individual receptor and the cellular response studied. Measurement of intracellular calcium levels with quin-2 showed that both fMet-Leu-Phe- and platelet-activating factor-mediated increases in quin-2 fluorescence were diminished as a result of pertussis toxin treatment. fMet-Leu-Phe-mediated calcium uptake was also inhibited. However, under conditions where fMet-Leu-Phe-mediated effects on cell function were completely abolished, only a partial inhibition of 3,4,5-trimethoxybenzoic acid 8-(diethylamino)octyl ester (TMB-8) sensitive calcium uptake was observed. A study of the linked reactions of chemotaxis, capping, and shape change revealed that chemotaxis was inhibited regardless of the chemoattractant utilized (zymosan-treated serum, fMet-Leu-Phe, and platelet-activating factor) and the associated reactions of Con A capping and fMet-Leu-Phe- or Con A-mediated shape change were reduced in pertussis toxin-treated cells. Our results suggest that multiple mediators of inflammation act through a pertussis toxin-sensitive GTP-binding protein that regulates the mobilization of internal calcium as well as calcium uptake and is, in addition, a key control element of shape change, capping, and chemotaxis.
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PMID:A pertussis toxin-sensitive GTP-binding protein in the human neutrophil regulates multiple receptors, calcium mobilization, and lectin-induced capping. 300 14


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