Activated α,β-Unsaturated Aldehydes as Substrate of Dihydroxyacetone Phosphate (DHAP)-Dependent Aldolases in the Context of a Multienzyme System

The utility for carbon-carbon bond formation of a multienzyme system composed of recombinant dihydroxyacetone kinase (DHAK) from Citrobacter freundii, the fructose bisphosphate aldolase from rabbit muscle (RAMA) and acetate kinase (AK) for adenosine triphosphate (ATP) regeneration has been studied. Several aldehydes with great structural diversity, including three alpha,beta-unsaturated aldehydes, have been analysed as acceptor substrates. It was found that alpha,beta-unsaturated aldehydes bearing an electron-withdrawing group in the beta position to the double bond with a trans configuration are good acceptors for RAMA in this multienzyme system. The aldol reaction proceeds with excellent D-threo enantioselectivity and the aldol adduct is obtained in good overall yield. The L-threo and D-erythro enantiomers are also accessible from rhamnulose 1-phosphate aldolase (Rha-1PA) and fuculose-1-phosphate aldolase (Fuc-1PA) catalysed reactions, respectively.