Scheme 13. (A) Chemical basis of IRED-y-to-go screen.⁶⁸ The oxidative activity of an IRED, acting on a secondary amine substrate, generates NADPH, which is used by diaphorase to reduce tetrazolium salt 28 to red dye 29. (B) The IRED-y-to-go screen was used to identify IREDs that enabled aminations of acetophenones 30 and the production of tertiary amines.⁶⁸ (C) The IRED-y-to-go screen enabled also identified enzymes for the amination of esters.^68,69.