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Manganese enzyme activation

Manganese ions enzyme activators, 6,578 probes, 6,563 RNA polymerases activation, 6, 585 transport microbes, 6, 569 plants, 6, 572 Manganese oxide colloidal... [Pg.161]

The mitochondrial dysfunctionality seen in manganese neurotoxicity might be related to the accumulation of reactive oxygen species (Verity, 1999). Mitochondrial Mn superoxide dismutase (MnSOD) is found to be low or absent in tumour cells and may act as a tumour suppressor. It is induced by inflammatory cytokines like TNF, presumably to protect host cells. In a rat model, iron-rich diets were found to decrease MnSOD activity, although a recent study reported that in rat epithelial cell cultures iron supplementation increased MnSOD protein levels and activity, but did not compromise the ability of inflammatory mediators like TNF to further increase the enzyme activity (Kuratko, 1999). [Pg.335]

F. Yamakura, K. Kobayashi, H. Ue, and M. Konno, The pH-dependent changes of the enzymic activity and spectroscopic properties of iron-substituted manganese superoxide dismutase. A study on the metal-specific activity of Mn-containing superoxide dismutase. Eur. J. Biochem. 227, 700—706 (1995). [Pg.207]

Many proteins, including many enzymes, contain hghtly bound metal ions. These may be inhmately involved in enzyme catalysis or may serve a purely structural role. The most common tightly bound metal ions found in metalloproteins include copper (Cu+ and Cu +), zinc (Zn +), iron (Fe + and Fe +), and manganese (Mn +). Other proteins may contain weakly bound metal ions that generally serve as modulators of enzyme activity. These include sodium (Na+), potassium (K+), calcium (Ca +), and magnesium (Mg +). There are also exotic cases for which enzymes may depend on nickel, selenium, molybdenum, or silicon for activity. These account for the very small requirements for these metals in the human diet. [Pg.146]

Catalases catalyze the conversion of hydrogen peroxide to dioxygen and water. Two families of catalases are known, one having a heme cofactor and the second a structurally distinct family, found in thermophilic and lactic acid bacteria. The manganese enzymes contain a binuclear active site and the functional form of the enzyme cycles between the (Mn )2 and the (Mn )2 oxidation states. When isolated, the enzyme is in a mixture of oxidation states including the Mn /Mn superoxidized state and this form of the enzyme has been extensively studied using XAS, UV-visible, EPR, and ESEEM spectroscopies. Multifrequency EPR and microwave polarization studies of the (Mn )2 catalytically active enzyme from L. plantarum have also been reported. ... [Pg.100]

The enzyme that catalyzes reaction 7 has been solubilized, 4" 141 and purified141 2000-fold. The enzyme activity is dependent on manganese ions. The enzymes catalyzing reactions 5 and 6 have not yet heen solubilized, purified, or separated, and, therefore, the substrate specificities indicated remain speculative. [Pg.309]

Magnesium (manganese) and calcium ions as enzyme activators 565... [Pg.541]

Manganese is involved in numerous biochemical reactions both as an integral part of metalloenzymes and as an enzyme activator. [Pg.56]

CD spectroscopy has also been used to study the metal-binding and reactivity properties of iron- and manganese-containing SODs. These enzymes metabolize the superoxide ion radical O2 into molecular oxygen and hydrogen peroxide. The Fe- and Mn-SOD enzymes are strictly metal specific. Jackson and Brunold show that, despite the fact that Fe replacement of Mn in the Mn-SOD enzyme [(Mn Fe)-SOD] results in an inactive enzyme, the CD spectrum of wild-type Fe-SOD and (Mn - Fe)-SOD are remarkably similar. This suggests that the destroyed enzyme activity, upon replacement of the metal, does not occm via distortion of the enzyme active site. [Pg.6442]

Some nitrite reductases contain iron and copper other enzymes active in these reactions contain manganese. Reactions catalyzed by copper and iron enzymes with NO, N2O, and N2 as products have also been reported. [Pg.612]

Manganese is a constituent of many important metalloen-zymes and also acts as a nonspecific enzyme activator. Mn " ions can be replaced by Mg, Co % and other cations during the activation of some enzymes. Some important manganese-dependent enzymes are discussed below. [Pg.1130]


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