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Aldol addition of dihydroxyacetone to N-Cbz-3- aminopropanal catalyzed by two different D- fructose-6-phosphate aldolases

Aldolases belong to a group of enzymes called lyases and they catalyze carbon-carbon bond formation [1]. In this work aldol addition of dihydroxyacetone (DHA) to N-Cbz-3-aminopropanal (aldehyde) was studied. The aldol product of the reaction is used as precursor in the production of D-fagomine, a naturally occurring iminosugar with remarkable biological properties [2]. The reaction was catalyzed by D-fructose-6-phosphate aldolase overexpressed in E. coli. Two different aldolases were investigated, FSA A129S and FSA A129S/A165G. The dependence of enzyme activity on pH was measured for these two enzymes. Furthermore, since aldehyde is not soluble in water, two different co-solvents (acetonitrile and dimethylformamide) were selected and the influence of these co- solvents and their volume percentage in the reaction mixture on the enzyme activity was studied using the initial reaction rate method. Enzyme kinetics was determined in the batch reactor and kinetic parameters of enzymes were compared. Aldol addition catalyzed by the two enzymes was carried out in the microreactor. Enzyme activity was followed during the experiments. References: [1] Lopez-Santin et al, Illanes ed., Springer, 2008, 333 – 352 [2] Castillo et al, Org. Lett. 2006, 8, 6067-6070.

aldolase; aldol addition; enzyme kinetics; microreactor

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