Phosphoenolpyruvate, enzymatic synthesis

Enzymatic synthesis relying on the use of aldolases offers several advantages. As opposed to chemical aldolization, aldolases usually catalyze a stereoselective aldol reaction under mild conditions there is no need for protection of functional groups and no cofactors are required. Moreover, whereas high specificity is reported for the donor substrate, broad flexibility toward the acceptor is generally observed. Finally, aldolases herein discussed do not use phosphorylated substrates, contrary to phosphoenolpyruvate-dependent aldolases involved in vivo in the biosynthetic pathway, such as KDO synthetase or DAHP synthetase [18,19]. 

Development of the chemical synthesis of ulosonic acids which mimics the enzymatic condensation is an interesting target [70]. As a model a reaction leading to KDO 8-phosphate (22) has been evaluated. In this reaction mediated by KDO 8-P synthetase D-arabinose 5-phosphate (A5P, 21) is reacted with phosphoenolpyruvate (PEP) (Scheme 7) [71]. 

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