Figure 1

A) Hydantoinase process for the synthesis of chiral D- or L-α-amino acids starting from racemic 5’-monosubstituted hydantoins via N -carbamoyl-α-amino acids applying a hydantoin racemase, a specific hydantoinase and a specific N -carbamoyl-α-amino acid hydrolase; B) proposed modified hydantoinase process for the synthesis of chiral D- or L-β-amino acids starting from racemic 6’-monosubstituted dihydropyrimidines via N -carbamoyl-β-amino acids applying a racemase, a dihydropyrimidinase and a N -carbamoyl-β-amino acid hydrolase; (1) 5’-monosubstituted hydantoin, (2) N -carbamoyl-α-amino acid, (3) α-amino acid, (4) 6’-monosubstituted dihydropyrimidine, (5) N -carbamoyl-β-amino acid, (6) β-amino acid; PheHyd: phenylhydantoin, N CPheGly: N -carbamoyl-α-phenylglycine, PheDU: phenyldihydrouracil, N CβPhe: N -carbamoyl-β-phenylalanine, IMH: indolymethyl hydantoin, N CTrp: N -carbamoyl-α-tryptophan, p ClPheDU: para -chloro-phenyldihydrouracil, p Cl N CβPhe: para -chloro- N -carbamoyl-β-phenylalanine.