Industrial Biotransformations

d-Amino acid transaminase
Bacillus sp.
1 = aspartate
2 = glutamate
3 = 2-oxo-aspartate
4 = 2-oxo-glutamate
Fig. 2.6.1.21 – 1
1) Reaction conditions
pH: 8.0
T: 42 °C
medium: aqueous
reaction type: amino group transfer
catalyst: whole cell
enzyme: d-alanine; 2-oxoglutarate aminotransferase (d-aspartase transaminase)
strain: Bacillus sp.
CAS (enzyme): [37277–85–3]
2) Remarks
O
R CO 2 -
+ H3N CO 2 -
D-1
CO 2 -
alternative amine donor:
+ H3N CO 2 -
D-2
CO2 -
E
O CO 2 -
O CO 2 -
EC 2.6.1.21
NSC Technologies,
Monsanto
● The main drawback of transaminases is the equilibrium conversion of about 50 %.
● Therefore in commercial application l-aspartate is often used as the amino donor for l-amino
acid transaminase. The product decarboxylates to pyruvic acid and carbon dioxide. Pyruvic acid
itself is also an α-keto acid and is converted by dimerisation using acetolactate synthase to acetolactate.
The latter undergoes spontaneous decarboxylation to acetoin that can be easily
removed and does not participate in other reactions.
3
4
CO 2 -
CO2 -
NH3 +
R CO 2 -
267