engleski

Enzyme catalyzed aldol addition of propanal and formaldehyde

In this work aldol addition of formaldehyde and propanal catalyzed by D-fructose-6-phosphate aldolase D6Q variant (FSA D6Q) was investigated. This reaction has not been studied up to now. The main focus was put on the kinetic model development, finding the best reactor mode and process conditions to obtain the maximum concentration of aldol product. Kinetic analysis of the reaction system was done and the reaction rate was described by the two substrate Michaelis-Menten kinetic model with included inhibitions by both substrates. It was found that propanal is very reactive at reaction conditions and causes formation of side-products with and without the presence of enzyme. Therefore, the kinetics of side-reactions were also investigated to ensure better applicability of the developed mathematical model, and to try minimizing the formation of side-products. The influence of pH value on the reaction is taken into account since a better product stability is achieved at pH 7 than at pH 8. The mathematical model was validated in the batch and fed-batch reaction mode. It is shown that the model describes the experimental data well. By using the simulation the conditions are calculated for performing a reaction in fed-batch mode that gives the highest product yield. Up to now the highest volume productivity of 287.3 g/L/d was obtained by this enzymatic synthesis.

biocatalysis, aldol addition

nije evidentirano