초록
Biphasic reactions offer an attractive alternative for the utilisation of enzymes for conversion of hardly water soluble substrates. Especially, the alcohol dehydrogenase from Lactobacillus brevis was successfully used for the reductive synthesis of enantiopure secondary aliphatic alcohols. With the enzymatic catalyst and the cofactor effectively retained in the reactive aqueous phase, the continuous operation was demonstrated by continuous addition and withdrawal of the non-reactive phase. The four tested substrates 2-heptanone, 2-octanone, 2-nonanone, and 2-decanone showed that the space time yield and turnover numbers (TON) of the enzyme decrease as the availability of the substrate decreases with increasing partition coefficients. Nevertheless, a TON<SUB>LbADH</SUB> of up to 478x10<SUP>3</SUP> could be achieved. Remarkably, the cofactor utilisation turned out to be very high and a TON<SUB>NADP^+</SUB> of more than 20x10<SUP>3</SUP> was easily achievable for both 2-heptanone and 2-octanone by substrate coupled cofactor regeneration with excess of 2-propanol.