Industrial Biotransformations

Fumarase
Corynebacterium glutamicum
1 = fumaric acid
2 = malic acid
Fig. 4.2.1.2 – 1
1) Reaction conditions
[1]: 0.97 M, 150 g · L –1 [154.14 g · mol –1 ] (slurry of calcium salt)
[2]: 0.87 M, 150 g · L –1 [172.16 g · mol –1 ] (slurry of calcium salt)
pH: 8.0
T: 25 °C
medium: aqueous
reaction type: C-O bond formation
catalyst: suspended whole cells
enzyme: (S)-malate hydrolyase (fumarase, fumarate hydratase)
strain: Corynebacterium glutamicum
CAS (enzyme): [9032–88–6]
2) Remarks
HOOC
COOH
● Only l-malate is produced, d-malate is not detectable.
● Microbial fumarases lead to a mixture of 85 % malate and 15 % fumarate.
E
+H2O
HOOC
1 L-2
COOH
EC 4.2.1.2
Amino GmbH
● According to German drug regulations (DAB 10) the fumaric acid content of malic acid has to
be less than 0.15 %.
● Fumaric acid separation is circumvented by forcing a quantitative transformation in a slurry
reaction (solubility of calcium malate and calcium fumarate is approx. 1 %).
● The reaction is carried out in a slurry of crystalline calcium fumarate and crystalline calcium
malate.
● The precipitation of the product shifts the equilibrium towards calcium malate (figure 4.2.1.2 – 2):
OH
463