Fig. 1: Characterization of the stereoselectivity of ancestral IREDs.
a Enzymatic asymmetric reduction of 1a used to investigate stereoselectivity evolution of IREDs. b Gas chromatogram profiles displaying the stereoselectivity of the last common ancestor N1 toward 1a. c Simplified phylogenetic tree showing the target evolution trajectory from N1 to N560. NX (X = 1, 2, 3 to 5, and 557, 558 to 560) represents the number of ancestral enzymes at each node. Light purple and yellow solid circles represent the percentage of S- and R-enantiomers produced by IREDs, respectively. Outgroup denotes ornithine cyclodeaminase sequences. d Enantiomeric excess (ee) of (R)-2a or (S)-2a generated by the ancestors within the focused trajectory and two extant imine reductases SIR from Streptomyces sp. GF3546 and ScIR from Streptomyces clavuligerus. The ee of N1–N560 was calculated from the average of triplicate experiments (n = 3). The data are presented as mean values ± SEM. The ee of SIR and ScIR cited from our pervious study20. Light purple and yellow bars represent the percentage of S- and R-enantiomers produced by IREDs, respectively.
