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)

Esterified milk proteins [methylated (Met) or ethylated (Et) alpha-lactalbumin (ALA), beta-lactoglobulin (BLG), and beta-casein (BCN)], unmodified native milk proteins, and native basic proteins (calf thymus histone and hen egg white lysozyme) were tested for their antiviral activity against the bacteriophage M13 and for their influence on its replication (except BCN). All esterified milk proteins showed an antiviral activity against the bacteriophage M13, proportional to the extent of esterification and, hence, to the increased basicity of the modified proteins. Antiviral activity of 100% Met-BLG disappeared after its pepsinolysis but not after its trypsinolysis. The antiviral activity of Met-BLG was much higher than that of native basic proteins (histone and lysozyme). One hundred percent Met-BLG and 73% Et-BLG inhibited the replication of bacteriophage M13 completely, whereas 60% Met-ALA inhibited phage replication partially. Calf thymus histone inhibited the replication of bacteriophage M13 at a lower extent (20%) than Met- and Et-BLG (100% inhibition). Protein concentration, pH, and concentration of the Escherichia coli culture in the preincubation medium of the virus were other factors influencing antiviral activity. Interactions of esterified proteins with the phage DNA (phenol extracted) followed the same pattern as observed during studies of the inhibition of the phage replication: Met-BLG > Et-BLG > or = Met-ALA.
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PMID:Inhibition of bacteriophage m13 replication with esterified milk proteins. 1671 99

Better understanding of tolerance and autoimmunity toward melanocyte-specific Ags is needed to develop effective treatment for vitiligo and malignant melanoma; yet, a systematic assessment of these mechanisms has been hampered by the difficulty in tracking autoreactive T cells. To address this issue, we have generated transgenic mice that express hen egg lysozyme as a melanocyte-specific neoantigen. By crossing these animals to a hen egg lysozyme-specific CD4 TCR transgenic line we have been able to track autoreactive CD4+ T cells from their development in the thymus to their involvement in spontaneous autoimmune disease with striking similarity to human vitiligo vulgaris and Vogt-Koyanagi-Harada syndrome. Our findings show that CD4-dependent destruction of melanocytes is partially inhibited by blocking Fas-Fas ligand interactions and also highlights the importance of local control of autoimmunity, as vitiligo remains patchy and never proceeds to confluence even when Ag and autoreactive CD4+ T cells are abundant. Immune therapy to enhance or suppress melanocyte-specific T cells can be directed at a series of semiredundant pathways involving tolerance and cell death.
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PMID:CD4 T cell-dependent autoimmunity against a melanocyte neoantigen induces spontaneous vitiligo and depends upon Fas-Fas ligand interactions. 1692 Sep 42

We describe a novel TCR-transgenic mouse line, TCR7, where MHC class II-restricted, CD4+ T cells are specific for the subdominant H-2b epitope (HEL74-88) of hen egg lysozyme (HEL), and displayed an increased frequency in the thymus and in peripheral lymphoid compartments over that seen in non-transgenic littermate controls. CD4+ T cells responded vigorously to HEL or HEL74-88 epitope presented on APC and could develop into Th1 or Th2 cells under appropriate conditions. Adoptive transfer of TCR7 Ly5.1 T cells into Ly5.2 rat insulin promoter (RIP)-HEL transgenic recipient hosts did not lead to expansion of these cells or result in islet infiltration, although these TCR7 cells could expand upon transfer into mice expressing high levels of HEL in the serum. Islet cell infiltration only occurred when the TCR7 cells had been polarized to either a Th1 or Th2 phenotype prior to transfer, which led to insulitis. Progression from insulitis to autoimmune diabetes only occurred in these recipients when Th1 but not Th2 TCR7 cells were transferred and CTLA-4 signaling was simultaneously blocked. These findings show that regulatory pathways such as CTLA-4 can hold in check already differentiated autoreactive effector Th1 cells, to inhibit the transition from tolerance to autoimmune diabetes.
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PMID:Breakpoints in immunoregulation required for Th1 cells to induce diabetes. 1695 44

Autoimmune uveoretinitis accounts for at least 10% of worldwide blindness, yet it is unclear why tolerance to retinal Ags is so fragile and, particularly, to what extent this might be due to defects in peripheral tolerance. To address this issue, we generated double-transgenic mice expressing hen egg lysozyme, under the retinal interphotoreceptor retinoid-binding promoter, and a hen egg lysozyme-specific CD4(+) TCR transgene. In this manner, we have tracked autoreactive CD4(+) T cells from their development in the thymus to their involvement in uveoretinitis and compared tolerogenic mechanisms induced in a variety of organs to the same self-Ag. Our findings show that central tolerance to retinal and pancreatic Ags is qualitatively similar and equally dependent on the transcriptional regulator protein AIRE. However, the lack of Ag presentation in the eye-draining lymph nodes results in a failure to induce high levels of T cell anergy. Under these circumstances, despite considerable central deletion, low levels of retinal-specific autoreactive CD4(+) T cells can induce severe autoimmune disease. The relative lack of anergy induction by retinal Ags, in contrast to the same Ag in other organs, helps to explain the unique susceptibility of the eye to spontaneous and experimentally induced autoimmune disease.
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PMID:Limited peripheral T cell anergy predisposes to retinal autoimmunity. 1737 84

Reactive nitrogen species are implicated in inflammatory diseases and cancers. Oxanine (Oxa) is a DNA lesion product originating from the guanine base through exposure to nitric oxide, nitrous acid, or N-nitrosoindoles. Oxanine was found to mediate formation of DNA-protein cross-links (DPCs) in the cell extract. We have previously characterized two DNA-protein cross-links from the reaction between Oxa and glutathione: namely, the thioester and the amide. In this study, lysozyme was used to study site-specific modification on protein by Oxa moieties in DNA. With the aid of nanoLC coupled with nanospray ionization tandem mass spectrometry, addition of Oxa was found at Lys13, Lys97, Lys116, Ser85, and Ser86 of lysozyme when it was treated with 2'-deoxyoxanosine (dOxo). Furthermore, incubation of lysozyme with Oxa-containing calf thymus DNA, produced by treating DNA with nitrous acid, led to lysozyme modification at Lys116, Ser85, and Ser86. Interestingly, none of the cysteine residues was modified by dOxo, in contrast with our previous findings that dOxo reacted with oxidized glutathione disulfide, forming the thioester. This might be due to the half-life of the dOxo-derived thioester being 2.2 days at the pH of incubation. Furthermore, the sites of modifications on lysozyme are in good agreement with the solvent accessibility of the residues. Since repair of Oxa-derived DPCs has not been extensively investigated, these results suggest that these stable DPCs might represent important forms of cellular damage caused by reactive nitrogen species involved in inflammationrelated diseases.
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PMID:Investigation of DNA-protein cross-link formation between lysozyme and oxanine by mass spectrometry. 1835 83

The interactions of lysozyme and calf thymus DNA (ctDNA) or thioglycolic acid (TGA) modified CdTe nanoparticles in aqueous solution have been studied by resonance light-scattering (RLS) spectroscopy. At pH 7.2 Britton-Robinson (BR) buffer solution and pH 7.4 phosphate buffered saline (PBS), the RLS signals of ctDNA and TGA modified CdTe nanoparticles were greatly enhanced by lysozyme in the region of 220-750 nm characterized by the peak around 306 and 353 nm, respectively. Under optimal conditions, the increase of RLS intensity of the two systems is proportional to the concentration of lysozyme. The linear range is 0.1-25 microg/ml for the lysozyme-ctDNA system, and 0.2-10.7 microg/ml for the lysozyme-TGA modified CdTe nanoparticles system. The detection limit is 0.041 microg/ml for the lysozyme-ctDNA system, and 0.083 microg/ml for the lysozyme-TGA modified CdTe nanoparticles system, respectively. Meanwhile lysozyme can also be used as a probe to determine the ctDNA. The increase of RLS intensity of the system is also proportional to the concentration of ctDNA. The linear range is 0.078-13 microg/ml. The detection limit is 0.024 microg/ml. Three kinds of samples were analyzed with satisfactory results.
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PMID:Study on the resonance light-scattering spectrum of lysozyme-DNA/CdTe nanoparticles system. 1877 22

We identify and characterize a special type of macrophage in the human thymic cortex that may act as professional scavengers of apoptotic thymocytes. These are large cells with clear cytoplasm, evenly distributed exclusively in the thymic cortex, and usually contain degraded nuclei in their cytoplasm. They are distinct from ordinary macrophages (OM) in the thymic cortex in expressing fascin, an actin-bundling protein specific for dendritic cells (DC), and in lacking lysozyme (LZM) and CD68. They are also different from DC in lacking major histocompatibility complex (MHC)-class II molecules. To distinguish them from OM and DC, we called them thymic cortical dendritic macrophages (TCDM). Both TCDM and OM are positive for DC-SIGN (CD209) and HAM56, whereas fascin(hi) MHC-class II(hi) medullary DC (mDC) are negative for these antigens. TCDM exhibit either dendritic or plump feature depending on cases examined. Plump TCDM usually contain several degraded nuclei, while dendritic TCDM contain one or two. These degraded nuclei are positive for active caspase-3 (aCasp-3), indicating that they are apoptotic thymocytes. In contrast to TCDM, LZM(hi) CD68(hi) OM are smaller round cells, distributed unevenly throughout the thymus, and do not contain apoptotic thymocytes at all. TCDM tend to adhere to capillaries with their dendrites or they make extensive contacts covering a large portion of the capillaries. Electron microscopic analysis confirmed the extensive contact between TCDM and capillaries and indicated that TCDM possess extremely electron-lucent, abundant cytoplasm with numerous tubulovesicular structures and secondary lysosomes. The finding of numerous condensed nuclei in most of the TCDM indicates that these cells represent a special type of fixed macrophages in the human thymic cortex, and that they play a central role in the clearance of apoptotic thymocytes.
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PMID:Identification and characterization of human thymic cortical dendritic macrophages that may act as professional scavengers of apoptotic thymocytes. 1892 98

A study was undertaken to determine the effect of a synthetic immunomodulator, i.e. methisoprinol applied in ovo, upon the hatchability of turkey poults under conditions of a standard hatchery as well as on their health status evaluated based on analyses of selected biochemical indices in their blood serum. Experiments were conducted on 5 groups of BUT 9 turkeys at the age of 5 days (35 birds in each group) hatched from eggs to which methisoprinol (VetAgro, Lublin, Poland) was applied in ovo at a dose of 5 mg (group I), 10 mg (group II) or 20 mg per egg (group III) on the 26th day of incubation. Turkeys hatched from eggs to which a physiological solution of NaCl was applied on the same day at a dose of 0.1 ml per egg (group IV) as well as those hatched from eggs without in ovo injection (group V) served as controls. Five hundreds eggs were used in each group. Hatchability was evaluated based on the number of hatched poults in respect of the number of eggs with live embryos transferred from the setting compartment to the hatching compartment, that were subjected to in ovo administration of the preparations according to the experimental design. Blood serum of the 5-day-old turkey poults was analyzed for activities of AST, ALP, LDH-L, CK, lysozyme and ceruloplasmine as well as for total protein and albumin contents. Analyses were also conducted for the immune system organ index - percentage contribution of organs of the immune system (spleen, thymus and the bursa of Fabricius) in the body weight of turkeys. The study demonstrated that methisoprinol administered to turkey embryos in ovo on day 26 of incubation at doses of 5, 10 or 20 mg per embryo did not induce any disturbances in the hatching process or affect its final result. In addition, it was shown not to exert any negative effect on the health status of the reared turkey poults.
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PMID:The influence of methisoprinol applied in ovo upon hatchability and health status of turkeys. 1964 50

Proteolytic activity of blood serum IgGs of 10 patients with systemic lupus erythematosis (SLE) was studied in comparison with such activity in 10 clinically healthy donors. Antibodies were precipitated from blood serum by saturation with 50% (NH4)2SO4 and IgG was isolated by the affinity chromatography on protein G-sepharose column. Histone H1 and core histones from the calf thymus, bovine myelin basic protein (MBP), lysozyme of chicken egg and bovine serum albumin (BSA) were used as substrates for proteolytic action. It was found that 4 of 10 preparations of IgGs possess an ability to hydrolyze both histone H1 and MBP. These antibodies practically did not cleave lysozyme of the chicken egg and BSA. Gel-filtration of antibodies under acidic condition and following examination of proteolytic activity of chromatographic fractions showed that histone H1 and MBP-hydrolyzing activity is attributable to IgG-antibodies. Thus, the presence of catalytically active antibodies (protabzymes) in the blood serum of patients with SLE has been demonstrated. Their origination and biological role are discussed.
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PMID:[Proteolytic activity of blood serum IgG in patients with systemic lupus erythematosis]. 1987 32

Using hen egg-white lysozyme, the effect of blood proteins on CD4 thymic cells was examined. A small fraction of i.v. injected hen egg-white lysozyme rapidly entered the thymus into the medulla. There it was captured and presented by dendritic cells (DCs) to thymocytes from two TCR transgenic mice, one directed to a dominant peptide and a second to a poorly displayed peptide, both presented by MHC class II molecules I-A(k). Presentation by DC led to negative selection and induction of regulatory T cells, independent of epithelial cells. Presentation took place at very low levels, less than 100 peptide-MHC complexes per DC. Such low levels could induce negative selection, but even lower levels could induce regulatory T cells. The anatomy of the thymus-blood barrier, the highly efficient presentation by DC, together with the high sensitivity of thymic T cells to peptide-MHC complexes, results in blood protein Ags having a profound effect on thymic T cells.
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PMID:Thymus-blood protein interactions are highly effective in negative selection and regulatory T cell induction. 1993 68


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