Important products of amino-acid metabolism

An alternative metabolic route for amino acids involves removal of the a-amino 

Amino acids can also undergo oxidative de-amination. Amino-acid oxidases use FAD as coenzyme and the reduced FAD produced is oxidised by 02  

It is interesting that there is a D-amino-acid oxidase as well as the expected one for l substrates. The raison d etre for the D-amino-acid oxidase is not known. Granted that bacterial cell walls and antibiotics of bacterial origin contain some D-amino acids, the amount of these that might be recycled from time to time scarcely warrants the existence of a gene and the synthesis of a special enzyme for the purpose. 

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