Industrial Biotransformations

Subtilisin
Bacillus licheniformis
H 2N H
COO
(R,S)-1
1 = phenylalanine-isopropylester
Fig. 3.4.21.62 – 2
● The uniqueness of this process is the continuous extraction with a second aqueous phase of
pH 3.5. The hydrolysis product, the amino acid, is charged at pH 7.5 and is not extracted into
the acidic aqueous phase.
● The non-converted (R)-amino ester can be racemized by refluxing in anhydrous toluene in the
presence of an immobilized salicylaldehyde catalyst.
3) Flow scheme
+ OH -
water, pH 7,5
water, pH 3,5
O
NH 2
Fig. 3.4.21.62 – 3
358
O
Subtillsin
pH
NaOH
E
H 2N H
+
H3N H
COO -
(S)-1
NH 2
COO
+
H +
H2N H
H2N H
COO
(R)-1
pH 7.5 pH 3.5
COOH
COO
HCl
EC 3.4.21.62
O
NH 2
shell phase
membrane
tube phase
pH
O