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)

For more than a decade we have exposed rabbits to different metals, usually in soluble form, and investigated the effects on the lungs. The metal concentrations have been around 1 mg/m3,i.e., not more than a factor of 10 above occupational threshold limit values. The exposure periods have been 1-8 months (6 hr/day, 5 days/week). We have studied especially the morphology and function of alveolar macrophages (AM), the morphology of alveolar type I and type II epithelial cells, and analyzed lung phospholipids. Several metals produce specific, complex effects. For example, metallic and soluble nickel (NiCl2) increase both number and size of the type II cells, increase the production of surfactant, and affect morphology and function of AM. Cobalt (CoCl2) induces a different effect on type II cells from nickel, causing the formation of nodules in these cells. Trivalent chromium [Cr(NO3)3] does not affect either type II cells or the amount of surfactant significantly, but markedly affects AM. The administered metals affect AM both directly and indirectly. For example, nickel induces an increased production of surfactant, resulting in overfed AM with an increased metabolic activity. However, nickel also induces a direct decrease in the release of lysozyme activity by AM. Our results emphasize the complexity of the effects on the lungs of inhaled agents, which can act both directly and indirectly on AM.
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PMID:Reaction of alveolar macrophages to inhaled metal aerosols. 139 56

Rabbits were exposed to 2 or 0.4 mg/m3 of cobalt as CoCl2 for 14-16 weeks (5 days/week and 6 hr/day). More macrophages were lavaged from the lungs of rabbits exposed to the higher Co2+ concentration, and the diameter and variation of the diameter of the macrophages were significantly larger than in controls. The activity of lysozyme in the lavage fluid and in the macrophages was increased in the two exposed groups. Some macrophages in the exposed animals were large and engorged with intracellular lamellar inclusions and lipid droplets. Most of these cells had a smooth surface. The oxidative metabolic activity measured by reduction of nitroblue tetrazolium was increased in the exposed groups. The number of yeast cell particles attached to the surface of the macrophages was increased in the group exposed to the high concentration, but the number of ingested particles was not affected by cobalt exposure. Apart from the fact cobalt increased lysozyme activity whereas nickel decreased it, cobalt produced the same type of effects on macrophages as nickel did in earlier studies. Cobalt affected only a minor proportion whereas nickel affected most macrophages. This can be explained by the fact nickel produced a general increase in the volume density of the type II cells while cobalt affected the type II cells only in some areas of the lungs.
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PMID:Rabbit alveolar macrophages after long-term inhalation of soluble cobalt. 378 Jun 47

Metal binding to lysozyme has received wide interest. In particular, it is interesting that Ni2+, Mn2+, Co2+, and Yb3+ chloride salts induce an increase in the solubility of the tetragonal form in crystals of hen egg white lysozyme at high salt concentration, but that Mg2+ and Ca2+ chloride salts do not. To investigate the interactions of the di- and trivalent metal ions with the active site of lysozyme and compare the effects of the di- and trivalent metal ions on molecular conformation of lysozyme based on the structural analysis, the crystal structures of hen egg white lysozyme grown at pH 4.6, in the presence of 0.5 M MgCl2, CaCl2, NiCl2, MnCl2, CoCl2, and YbCl3, have been determined by X-ray crystallography at 1.58 A resolution. The crystals grown in these salts have an identical space group, P4(3)2(1)2. The molecules show no conformational changes, irrespective of the salts used. Ni2+ and Co2+ binding to the Odelta atom of Asp52 in the active site at 1.98 and 2.02 A, respectively, and Yb3+ binding to both the Odelta atom of Asp52 and the Odelta1 atom of Asn46 at 2.25 A have been identified. The binding sites of Mn2+, Mg2+, and Ca2+ have not been found from different Fourier electron density maps. The Ni2+ and Co2+ ions bind to the Odelta atom of Asp52 at almost the same position, while the Yb3+ ion takes a different position from the Ni2+ and Co2+ ions. On the other hand, the anion Cl-, interacting with the Oeta atom of Tyr23 at a site of about 2.90 A, has also been determined for each crystal.
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PMID:Structural details at active site of hen egg white lysozyme with di- and trivalent metal ions. 1613 73