Industrial Biotransformations

Aminoacylase
Aspergillus oryzae
S COOH
1) Reaction conditions
[1]: 0.6 M, 97.96 g · L –1 [163.27 g · mol –1 ]
[Co2+ ]: 0.5 · 10 –3 M, 0.029 g · L –1 [58.93 g · mol –1 ] (activator)
pH: 7.0
T: 37 °C
medium: aqueous
reaction type: hydrolysis
catalyst: solubilized enzyme
enzyme: N-acyl-l-amino-acid amidohydrolase (aminoacylase, acylase 1)
strain: Aspergillus oryzae
CAS (enzyme): [9012–37–7]
2) Remarks
HN
O
D,L-1 D-2
1 = N-acetyl-methionine
2 = N-acetyl-methionine
3 = methionine
4 = acetic acid
Fig. 3.5.1.14 – 1
E
Co 2+
S COOH
● The N-acetyl-d,l-amino acid precursors are conveniently accessible through acetylation of d,lamino
acids with acetyl chloride or acetic anhydride under alkaline conditions in a Schotten-
Baumann reaction.
● As effector Co 2+ is added to increase the operational stability of the acylase.
● The unconverted acetyl-d-methionine is racemized by acetic anhydride under alkaline conditions
and the racemic acetyl-d,l-methionine is recycled.
● The racemization can also be carried out in a molten bath or by racemase.
● Product recovery of l-methionine is achieved by crystallization, because l-methionine is much
less soluble than the substrate.
● A polyamide ultrafiltration membrane with a cutoff of 10,000 dalton is used.
HN
EC 3.5.1.14
● Several proteinogenic and non-proteinogenic amino acids are produced in the same way by
Degussa-Hüls:
O
S COOH
HO
+
NH2
+
O
L-3
4
Degussa AG
407