d-Amino Acids

Publisher Summary This chapter describes a method for the enzymatic determination of D-amino acids. The chapter highlights that the oxidative deamination of α-amino acids has been known since 1909. It has been shown that this process consumed oxygen and resulted in the formation of ammonia and α-keto acids. Kidney tissue contains an enzyme, D-amino acid oxidase, which specifically deaminates D-amino acids and requires flavine adenine dinucleotide (FAD) as coenzyme. Greenstein used this enzyme to prepare the pure L-isomers from amino acid racemates. The chapter shows the activity of a D-amino acid oxidase preparation from sheep kidney with various D-amino acids. The manometric method is based on the principle that D-amino acid oxidase catalyzes the reaction. The imino acid decomposes spontaneously. A mole of D-amino acid yields a mole of α-keto acid and a mole of ammonia, and 0.5 mole of oxygen is consumed. This oxygen consumption is determined and, with the exception D-amino-adipic acid, is a measure of the total amount of D-amino acids contained in the sample.