Bacteria manganese catalase

Manganese catalases, sometimes referred to as pseudocatalases, are found in lactic acid bacteria and in thermophihc bacteria. The molecular weight of these enzymes ranges from 170 to 210 kDa. They may form unusual ohgomeric structures like homopentamers and homohexamers. Unhke heme catalases, they are not inhibited by CN or Nj [ 197 ]. 

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. ... 

Mariganese-containing catalases have been isolated from three species of bacteria Lactobacillus plantarum [27], Thermus ihemtophUus [28], and Thermoleophilum album [18]. X-ray crystallographic structure analysis [29] has shown that these catalases contain a dinudear manganese core. During catalysis, the dinudear manganese active site cydes between the Mn"- and Mn2"oxidation states [30]. 

Superoxide dismutases of some microorganisms (such as Escherichia coli) and some animals contain Mn " /Mn + ions instead of copper and zinc ions as the cofactor (see Section 3.8.1.13.2). Catalases of some microorganisms (e.g. the bacteria Lactobacillus plantarum) contain manganese instead of haem iron. 

No lactic acid bacteria possess cytochrome. The catalase activity is generally assumed not to exist, but several species of bacteria (Lactobacillus, Pediococcus and Leuconostoc) can synthesize a manganese-dependent, non-hemic pseudocatalase. A hemic catalase activity has been identified in many strains. 

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