Pseudocatalases

P,2, S transition, ratio r, 35 368 Prussian Blue, 46 41 -like phases, 43 245-249 magnetic ordering, 43 246-247 magnetic properties, 43 248 relation to Berlin green, 8 120-121 structure studies on, 8 119-120 Prussiates, M6ssbauer spectrum of, 6 464-466 Pseudoazurins, 36 382 x-ray crystal structures, 36 389-390 Pseudocatalase, 40 379... 

The bacterium Lactobacillus plantarum and its closest allies are unusual in that they are aerobic organisms but do not produce a superoxide dismutase. This bacterium instead accumulates Mn(II) to an intramolecular level on the order of 25 mM (150-152). In vitro studies indicated that Mn(II) formed a complex with lactate which possessed significant superoxide activity (153). These bacteria are additionally unable to produce heme and, consequently, when grown in the absence of heme, produce a hemeless catalase, or pseudocatalase (154-158). Unlike heme-containing catalases, the enzyme is not inhibited by cyanide or azide, and the addition of either Mn or Fe into the growth medium increased the amount of the pseudocatalase present. However, neither of the metals could be detected in partially purified enzyme assays (157). 

In 1983, Kono and Fridovich reported the isolation of a pseudocatalase from L. plantarum which contained manganese (159). The enzyme was 172 kDa the original report gave a subunit of 28.3 kDa and 1.12 0.37 atoms of manganese per subunit. The visible spectrum of the enzyme displayed an absorption maximum at 470 nm (e = 1.35 x 103 M l cm-1) with shoulders at 398 and 500 nm. This spectrum is extremely similar to those of Mn superoxide dismutases (Section II,A) and, thus, indicative of the presence of Mn(III). Comparison of the amino acid compositions of the two enzymes suggested that they are not closely related. The pseudocatalase possessed no superoxide dismutase activity but had a turnover number of 3.9 x 10s mol of peroxide per mole of enzyme per second. 

An apparently similar catalase has also been isolated from the bacterium T. thermophilus (163). The enzyme is approximately 210 kDa each subunit is 34 kDa, indicating the existence of six subunits. The visible spectrum of the enzyme has a maximum near 440 nm (e = 7.7 x 102 M 1 cm-1) with shoulders at 460 and 500 nm. The similarity of the visible spectrum when compared to that of the pseudocatalase of L. plantarum led the authors to speculate that this might be a Mn pseudocatalase however, no metal analyses were reported. Additionally, the enzyme was inhibited by hydroxylamine, but it was also sensitive to azide. 

The nonheme catalases are sometimes referred to as pseudocatalases. However, this is inappropriate since there is nothing pseudo about their catalase activity. They are better described as Mn catalases. Bacteria that lack Mn catalase (either genetically or through inactivation of the enzyme) show decreased viability, suggesting that Mn catalase does, in fact, play a physiological role in the detoxification of H2O2. 

The catalase (or pseudocatalase) from Lactobacillus plantarum is also believed to contain a dimanganese(III) site in the oxidized form. It can be reduced to dimanganese(II) or superoxidized to a Mn Mn " state. The last complex shows a 16-line EPR spectrum (189). The visible spectrum of the dimanganese(III) form shows a strong absorption at... 

Beyer, W.F. and Fridovich, I. 1985. Pseudocatalase from Lactobacillus plantation Evidence for a homopentameric structure containing two atoms of manganese per subunit. Biochem. 24, 6460-6467. 

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 ]. 

Manganese complexes as models for manganese-containing pseudocatalase enzymes Synthesis, structural and catalytic activity studies... 

Kono Y, Eridovich I. 1983. Isolation and characterization of the pseudocatalase of Lactobacillus plantarum A new manganese-containing enzyme. J Biol Chem 258 6015-6019. 

Prototype fast reactors fuel reprocessing, 955 Prussian blue in cyclic water cleavage hydrogen and oxygen production, 525 electrode modification, 21 Pseudobactin, 678 animal infections, 679 Pseudocatalase... 

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. 

Characteristics Gram positive, non-spore forming, facultative anaerobic, catalase negative (mi blood agar same strains reveal pseudocatalase), rmmotile, alpha haemolytic or nonhaemolytic, anaerobic and aerobic metabolism ... 

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