Siegel and Zanghellini et al, Science, 329, 309-313. (2010)

Structure of a designed Diels-Alderase. (A) Surface view of the design model (DA_20_00, green) bound to the substrates (diene and dienophile, purple). The catalytic residues making the designed hydrogen bonds are depicted as sticks. (B) Overlay of the design model (DA_20_00,brown) and crystal structure of DA_20_00_A74I (green).  The crystal structure shows that the design was within atomic level accuracy (0.5A all-atom RMSD)