Fig. 4: Insights into the mechanism of stereoselectivity inversion.

Stereoview of the molecular docking results for substrate 1a in the active pocket of N559 (a) and N559-M6 (b). The active pocket is displayed in surface representation. The docked 1a, cofactor NADP⁺, and residue 170 (D170 in N559 and Y170 in N559-M6) are shown as sticks. The red dashed line denotes the formation of a hydrogen bond between substrate 1a and Y170. The black arrows indicate the transfer of hydride from C4 of the nicotinamide ring of NADP⁺ to the carbon atom of the imine bond in 1a.