Industrial Biotransformations

Amidase
Klebsiella terrigena
● After completition of conversion the cells are removed by centrifugation and the supernatant
is concentrated 10-fold at 60 °C under reduced pressure. The product precipitates by acidifying
with conc. HCl (pH 1).
● Using the strain Burkholderia DSM 9925 instead of Klebsiella DSM 9174 leads to (R)-piperazine-2-carboxylic
acid (99 % ee, 22 % yield).
● (S)-Piperazine-2-carboxylic acid has also been prepared by kinetic resolution of racemic 4-(tertbutoxycarbonyl)piperazine-2-carboxamide
with leucine aminopeptidase and of (R,S)-n-octylpipecolate
with Aspergillus lipase. Both processes show practical disadvantages in starting
material preparation and biocatalyst availability.
3) Flow scheme
Not published.
4) Process parameters
yield: 41.0 %
ee: 99.4 %
reactor type: batch
capacity: multi kg
residence time: 32 h – 76 h
down stream processing: precipitation
company: Lonza AG, Switzerland
5) Product application
● The product is used as an intermediate for pharmaceuticals, e.g. the orally active HIV protease
inhibitor crixivan from Merck:
Fig. 3.5.1.4 – 3
N
● It is also a precursor of numerous bioactive compounds.
380
N
N
t-BuNH O
OH
O
H
N
OH
EC 3.5.1.4