Reactions were set up in a Coy chamber using degassed buffers and solvents that had been allowed to equilibrate in the COY chamber for at least 24 h. EREDS (<200 µL aliquots) were thawed in the COY ante chamber during over several vacuum cycles and allowed to equilibrate for approx. 15 min. Stock solutions were prepared in the COY chamber. To 1.5 mL glass vial with a screw top and PTFE septum was added (in the following order) Tris-HBr (50 mM, pH 7.5, 182-325 µL), D-Glucose (50 µL, 550 mM stock in Tris-HBr), NADP + (50 µL, 5 mM stock in Tris-HBr), JM GDH-101 (25 µL, 10 mg/mL stock in Tris-HBr), styrene (25 µL, 200 mM stock in DMSO), α-bromoacetophenone (25 µL, 200 mM stock in DMSO), and ERED (0-143 µL, 490-1300 µM), to a final reaction volume of 500 µL. Biotransformations were incubated in an Eppendorf Thermomixer at 25 °C, 750 rpm for up to 24 h inside the COY chamber. Reactions were quenched aerobically by addition of acetonitrile (500 µL). HPLC samples were prepared by adding 200 µL of quenched reaction to 800 µL of acetonitrile, precipitated protein was removed by centrifugation (21,000 g, 2 min). GC-MS samples were prepared by extracting the remaining quenched reaction mixture with 600 µL EtOAc. Details on analytical methods, and characterization of 3aa and 3ha can be found in the electronic supporting information.