a plant peptide amidase from the flavedo of oranges is known ; this can be obtained only in small quantities and is seasonal . the proposed new enzymes are microbial peptide amidases which can be obtained from micro - organisms recovered from soil samples in a “ double screening ” and grown . these microbial peptide amidases are particularly useful for the production of peptides and n - terminal - protected amino acids , racemate splitting of n - protected amino acid amides , obtaining non - proteinogenous d - amino acids , and obtaining new n α - protected d - amino acid amides .