Multiphase Bioreactor Design

strategy requires the use of a cofactor regenerating enzyme and an inexpensive sacrificial
substrate (Figure 6.16a).
This enzyme uses the extra substrate to catalyse the regeneration of the cofactor that
was spent in the main reaction. The criteria used for the choice of the cofactor
regenerating

Figure 6.16 Cofactor regeneration by:

a) coupling of enzymes and b) coupled

substrate approach (S 1 —main

substrate, S2—auxiliary substrate, P 1 —

main product, P 2 —secondary product,

CoF—cofactor, CoF*—spent cofactor,

E 1 , E 2 and E—enzymes).

Table 6.6 Reactions with cofactors

Enzyme-reaction description Reference

Synthesis of L-methionine and L-phenylalanine from the N-acetyl-DL-
derivatives by acylase

Leuchtenberger et al.,

1984

Synthesis of L-malic acid by the fumarase stereoselective addition of
water to fumaric acid

Leuchtenberger et al.,

1984

Synthesis of L-leucine with NADH (PEG bound) regeneration by
leucine and formate dehydrogenases Leuchtenberger et al., 1984;
Ohshima et al., 1985;

Kragl et al., 1996a;

Wichmann et al., 2000

Transformation of LD-lactate via pyruvate to L-alanine with NADH
(PEG bound) regeneration

Wandrey et al., 1984

Synthesis of L-and D-2-hydroxyisocaproic acid by dehydrogenases
with NADH (PEG bound) regeneration

Wichmann et al., 1984

Synthesis of glucose 6-phosphate by hexokinase with ATP regeneration
by acetate kinase

Berke et al., 1984, 1988

Synthesis of L-lactate with NAD (PEG bound) regeneration by lactate
and malate dehydrogenases

Hayakawa et al., 1985

Enzymatic membrane reactors 169