The Active Site of an Enzyme Can Host Both Enantiomers of a Racemic Ligand Simultaneously

Two in one: Proteins usually bind only one enantiomer of a racemic ligand. Now a new binding mode for chiral drugs has been identified by protein crystallography. The homodimeric enzyme PhzA/B (in the picture the monomers are yellow and magenta) can host both enantiomers of a racemic ligand (light and dark gray) in its active site at the same time (dark red Br, blue N, light red O).