Comparison of these chromatograms with those of synthetic standards confirmed the presence of nearly equal amounts of both L-and D-2'/3'-fAla-ester adenosines. These results were consistent with racemisation of the formylalanyl residue during synthesis of the fAla mixed anhydride 5-mer, followed by the transfer of both L-and D-fAla residues. Repeating these experiments, but starting with D-fAla, afforded similar transfer yields (13% nicked loop and 50% nicked duplex, Fig. ) and resulted in nearly identical chromatograms (Fig. and).