On the reaction of D-amino acid oxidase with -chloroalanine.

Abstract

The reactions of ᴅ-amino acid oxidase with β-chloro-ᴅ-alanine and β-chloro-ʟ-alanine have been described. Both the holoenzyme and the apoenzyme catalyse the deamination of β-chloro-ʟ-alanine to keto acid without any consumption of oxygen or oxidation-reduction of the enzyme-bound FAD. The anaerobic reaction of the holoenzyme with β-chloro-ᴅ-alanine involves three phases with respect to the reduction of the enzyme-bound FAD, the rapid formation of an intermediate spectral species followed by a steady state of this intermediate and the last decay of the intermediate to the fully reduced enzyme. The rate of keto acid formation decreases as the reaction proceeds and ceases at the beginning of the conversion of the intermediate to the fully reduced enzyme. The aerobic reaction of the holoenzyme with β-chloro-ᴅ-alanine is biphasic. The first rapid oxygen consumption is followed by the second slow oxygen consumption. The second slow phase disappears by treating the enzyme with glutathione before the addition of substrate.