Taking advantage of the catalytic promiscuity of pyrimidine-catabolism enzymes (dihydropyrimidinase (E.C. 3.5.2.2), N-carbamoyl-beta-alanine amidohydrolase (E.C. 3.5.1.6)), the production of different p-alanine derivatives starting from 5- and 6-monosubstituted dihydrouracils has been evaluated using a mimesis approach. In this work, the S-enantioselective character of dihydropyrimidinase from Sinorizhobium meliloti toward 6-monosubstituted dihydrouracil derivatives has been shown. An inverted R-/S-enantioselectivity of N-carbamoyl-beta-alanine amidohydrolase from Agrobacterium tumefaciens toward two different N-carbamoyl-beta-amino acids has been proved. Our results have shown for the first time that this mimetic tandem constitutes an interesting biotechnological tool for the preparation of different P-alanine derivatives in an environmentally friendly way, allowing the production of enantioenriched (R)-alpha-phenyl-beta-alanine (e.e. >95%) and (R)-alpha-methyl-beta-alanine (e.e. >90%). (C) 2012 Elsevier Ltd. All rights reserved.