"The development of multienzymatic transformations offers great advantages over classical stepwise syntheses, avoiding the isolation and purification of reaction intermediates that can be unstable under determined conditions or even difficult to isolate from the reaction medium. This chapter discloses practical bioprocesses described in the literature over recent years, involving the action of two or more enzymes in a linear or cyclic mode. The combination of enzymes for the (stereoselective) production of several families of organic compounds has been discussed, paying special attention to those protocols that describe product isolation. Therefore, the addition order of reagents and enzymes, substrate concentrations, or pH values will be key parameters that extraordinarily affect the enzymatic catalysis, so their influence in the enzymatic catalysis will be exhaustively analyzed to select between cascade and sequential approaches."
Highlights:
- "The reaction setup was based in the use of eight tea bags of PfBAL for 32 ml reactions, which was successfully achieved in a sequential mode under a microaqueous system (triethanolamine buffer pH 9.0 and 97.5% v/v MTBE). Therefore, the carboligation was developed in a high benzaldehyde concentration (500 mM), followed by feeding of acetaldehyde in portions and eight tea bags containing RasADH using cyclohexanol for cofactor recycling purposes, isolating 1.8 g of (1R,2R)-1-phenylpropane-1,2-diol (75.7% yield) after extraction and column chromatography. Interestingly, the enzyme catalytic system was used over four cycles without apparent activity loss. Two years later, the scale-up to 140 ml scale reaction was described using a SpinChem reactor [79]."
- citation [79]: Wachtmeister, J., Mennicken, P., Hunold, A., and Rother, D. (2016). Modularized biocatalysis: immobilization of whole cells for preparative applications in microaqueous organic solvents. ChemCatChem, 2016, 8(3), pp. 607–614.