Monooxygenase imidazoleacetate

To clarify the reaction mechanism of monooxygenase, we have recently purified two monooxygenases from pseudomonads. Imidazoleacetate monooxygenase (5) and L-lysine monooxygenase (JO) were obtained in crystalline form, and both were shown to be flavoproteins. The former requires an exogenous hydrogen donor, but the latter utilizes the hydrogen atoms of L-lysine. 

Imidazoleacetate monooxygenase was purified about 250-fold from a cell-free extract of a pseudomonad and was obtained in crystalline form (Figure 1). The specific activity of the crystalline enzyme was 25.0 /xmoles/min./mg. protein, and on the basis of a molecular weight of 90,000 its molecular activity was estimated to be 2000 at 24°C. 

IMIDAZOLEACETATE HYDROXYLASE INDOLEAMINE 2,3-DIOXYGENASE myo-INOSITOL OXYGENASE JUGLONE MONOOXYGENASE KYNURENINE 3-HYDROXYLASE LACCASE... 

Imidazoleacetate and i.-lysine monooxygenases from pseudomonads were obtained in crystalline form. Both enzymes were established to contain FAD probably as a sole cofactor. Available evidence indicates that the reaction catalyzed by these enzymes involves the reduction of FAD, the monooxygenation of substrate, and the reoxidation of reduced FAD. The mechanism of activating molecular oxygen by these FAD-containing monooxygenases is discussed. 

Table I. Estimations of Iron and Copper of Imidazoleacetate and L-Lysine Monooxygenases, /miole...

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