Abstract D-Enantiomers of N-acylated 1-aminoethylphosphonic and 1- aminoethylphosphonous acids were able to be hydrolyzed with high concentrations of penicillin acylase in a reasonable time period. This finding was used to prepare both L-and D-enantiomers of these phosphorus analogues of alanine by stepwise enzymatic hydrolysis of their racemic N-phenylacetyl derivatives using the same enzyme-penicillin acylase-by ...