Catalases from Micrococcus lysodeikticus

Catalase from Micrococcus lysodeikticus provides a rare example of water coordinated directly to heme-iron (Fe—O = 2.28 A). This ligand water is hydrogen-bonded to another water molecule resident in the heme pocket. ... 

Herbert and Pinsent (161) have isolated crystalline catalase from Micrococcus lysodeikticus. The washed organisms were first lysed with crystalline lysozyme. The activity (Kat. F.) of crystalline bacterial catalase is 90,000 units. Its molecular weight as estimated from its hemin content lies between 226,000 and 248,000. The enzyme composes about 2% of the dry weight of the cells. 

Application and Principle This procedure is used to determine the catalase activity, expressed as Baker Units, of preparations derived from Aspergillus niger var., bovine liver, or Micrococcus lysodeikticus. The assay is an exhaustion method based on the breakdown of hydrogen peroxide by catalase and the simultaneous breakdown of the catalase by the peroxide under controlled conditions. 

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