Table 1.

Screening an initial panel of EREDs for cyclization.

Entry	‘Ene’-Reductase	Yielda (%) of 2a	erb	Yield (%) of 3
1	OPR1	31	80:20	9
2	NCR	20	79:21	19
3	PETNr	66	66:34	19
4	ERED-30c	94	65:35	6
5	No enzyme	0	n.d.d	0
6	No NADPH regeneration	0	n.d.	0

Reaction conditions: α-bromoketone (1 mg, 0.004 mmol), GDH-105 (0.5 mg), NADP⁺ (0.5 mg), glucose (5 mg) and purified ‘ene’-reductases (2 mol%) in 50 mM Tris-HBr buffer pH 8.0, with 5% DMSO (v/v) as cosolvent, final total volume is 500 μL. Reaction mixtures were shaken under anaerobic conditions at room temperature for 24 h.

^aYield determined via LCMS relative to an internal standard (TBB).

^bEnantiomeric ratio (er) determined by HPLC on a chiral stationary phase.

^cERED-30 (1 mol%) was screened from a genetically diverse EREDs library from Prozomix.

^dn.d., not determined.