Scheme 1: A -Generation of L G3P (1a) from L-glyceraldehyde (15) via glycerokinase from Cellumonas sp B-Generation of D-G3P ( ) from D-glyceraldehyde (1b) via dihydroxyacetonekinase from Citrobacter freundii For both cascades, enzyme loadings were optimized (supplementary 8.2.1) and the cascades were then screened towards a selection of the substrates from the initial panel (Figure ). In general a similar pattern of activity for the WT and the two variants was seen compared to the initial screen. However, for both cascades, when starting from enantiomerically pure glyceraldehyde only a single product peak was observed in the HPLC traces (compared to two peaks for DL-G3P) which suggest the formation of a single product diastereomer at the 2-position as desired (supplementary 11.15.1).