Lysine monooxygenase

LYSINE MONOOXYGENASE MALATE DEHYDROGENASE MELILOTATE HYDROXYLASE... 

LYSINE MONOOXYGENASE LYSYL HYDROXYLASE MANDELATE 4-MONOOXYGENASE MELILOTATE HYDROXYLASE METHANE MONOOXYGENASE... 

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. 

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. 

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

L-Lysine monooxygenase from a pseudomonad was purified approximately 100-fold, and the enzyme was crystallized (JO) (Figure 4). Its specific activity was 10.5 /xmoles/min./mg. protein. The molecular weight was estimated to be 191,000 and the molecular activity was calculated to be 2082 at 34°C. 

Figure 5. Absorption spectrum of L-lysine monooxygenase. Protein, 0.62% for visible region and 0.048% for ultraviolet region...

Figure 6. Reduction of i.-lysine monooxygenase with sodium di-thionite at pH 7.0 (left) and with i -lysine at 0.1 mM. Numbers indicate the incubation time in hours (right)...

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