Industrial Biotransformations

Dehalogenase
Pseudomonas putida
1) Reaction conditions
[1]: > 0.1 M, 10.9 g · L –1 [108.52 g · mol –1 ]
pH: 7.4
T: 30 °C
medium: aqueous
reaction type: C-halide hydrolysis
catalyst: suspended whole cells
enzyme: 2-haloacid halidohydrolase (2-haloacid dehalogenase)
strain: Pseudomonas putida
CAS (enzyme): [37289–39–7]
2) Remarks
2
Cl
COOH
● Pseudomonas putida is a robust organism that grows rapidly on cheap carbon sources even in
presence of high substrate concentrations.
● Since, at alkaline pH, 2-chloropropionic acid racemizes rapidly it is important that the dehalogenase
retains its high specific activity at neutral pH.
● The K M-value is very low so that the reaction rate remains high with typical end concentrations
of the substrate of 1 g · L –1 .
● Since the stability of the cells is poor, the steps of fermentation and biotransformation are carried
out separately.
● Usually an immobilization method would be used but in this case a special cell drying method
is applied, where only 10 % enzyme activity is lost and the solid biocatalyst can be stored for
over 12 months without deactivation.
● The main steps for the production of (S)-2-chloropropionic acid are:
1. Continuous fermentation
2. Biocatalyst preparation and drying
3. Biocatalyst storage
4. Fed-batch biotransformation
5. Biocatalyst separation
6. Solvent extraction of product
E
+ H 2O
- HCl
Cl
COOH
(R,S)-1 (S)-1 (S)-2
+
OH
COOH
EC 3.8.1.2
1 = 2-chloropropionic acid
2 = lactic acid Astra Zeneca
Fig. 3.8.1.2 – 1
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