short communications
The crystal structures of D-amino-acid amidase (DAA) from Ochrobactrum anthropi SV3 in complex with L-phenylalanine and with L-phenylalanine amide were determined at 2.3 and 2.2 Å resolution, respectively. Comparison of the L-phenylalanine amide complex with the D-phenylalanine complex reveals that the D-stereospecificity of DAA might be achieved as a consequence of three structural factors: (i) the hydrophobic cavity in the region in which the hydrophobic side chain of the substrate is held, (ii) the spatial arrangement of Gln310 O and Glu114 O2 that fixes the amino N atom of the substrate and (iii) the existence of two cavities that keep the carboxyl/amide group of the substrate near or apart from Ser60 Oγ.
Supporting information
PDB references: D-amino-acid amidase-L-phenylalanine complex, 2efu, r2efusf; D-amino-acid amidase-L-phenylalanine amide complex, 2efx, r2efxsf