Fructose-6-Phosphate Aldolase An Alternative to DHAP-Dependent Aldolases

Fructose-6-Phosphate Aldolase An Alternative to DHAP-Dependent Aldolases  

Although fructose-6-phosphate aldolase (FSA) does not belong to the DHAP-dependent aldolases group, it deserves to be mentioned in this chapter as it can be considered as an alternative to those enzymes, or at least, an alternative to FBPA. FSA was described for the first time by Schiirmann and Sprenger in E. coli K-12 strain MG1655 [50]. The enzyme is a class I aldolase with a homodecameric 

N-Alkylated derivatives could be obtained by catalytic reductive amination from a mixture of D-fagomine, or its linear precursor, and the corresponding aldehyde. 

Using a similar strategy, Wong et al. have also reported the synthesis of several iminocyclitols [52]. These authors use 2-azido aldehydes as acceptor to prepare five-membered iminocyclitols and N-Cbz-3-amino aldehydes to prepare six-membered iminocyclitols. Taking advantage of the donor tolerance of FSA, they also employ hydroxyacetone and l-hydroxy-2-butanone to obtain several known and novel iminocyclitols. 

FSA is an interesting novel tool in chemoenzymatic synthesis. It use greatly simplifies the enzymatic procedures based on the use of DffAP-dependent aldolases since it is employs non-phosphorylated donors and, as a consequence, the reaction products do not require a subsequent dephosphorylation step. Unfortu-natly, only one stereoconfiguration of the aldol adduct is accessible. 

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