Fig. 2

Engineering cofactor or co-substrate balance. a NAD(P)H regeneration systems formed via coupling with a regeneration reaction [56]; b redox self-sufficient amination via coupling with an alcohol dehydrogenase, l-alanine-dependent transaminase and l-alanine dehydrogenase [62, 63]; c redox self-sufficiency via a two-enzyme cascade for the hydrogen-borrowing amination of alcohols [54]; d reconstitution of TCA cycle using a DAOCS-catalysed reaction for 2-OG supply and regeneration [66]; e cofactor self-sufficient system established via a bridging mechanism (enzymes) to enable the simultaneous regeneration of cofactors and redox equivalent