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Appl. Environ. Microbiol., Oct 1996, 3794-3799, Vol 62, No. 10
K Bartsch, R Schneider and A Schulz
We have isolated and characterized an aspartate transaminase
(glutamate:oxalacetate transaminase, EC 2.6.1.1) from the thermophilic
microorganism Bacillus stearothermophilus. The purified enzyme has a
molecular mass of 40.5 kDa by sodium dodecyl sulfate gel analysis, a
temperature optimum of 95 degrees C, and a pH optimum of 8.0. The
corresponding gene, aspC, was cloned and overexpressed in Escherichia coli.
The recombinant glutamate:oxalacetate transaminase protein was used in
immobilized form together with 4-aminobutyrate:2-ketoglutarate transaminase
(EC 2.6.1.19) from E. coli for the production of L- phosphinothricin
[L-homoalanin-4-yl-(methyl)phosphinic acid], the active ingredient of the
herbicide Basta (AgrEvo GmbH), from its nonchiral 2-keto acid precursor
2-oxo-4- [(hydroxy)(methyl)phosphinoyl]butyric acid (PPO). In this new
coupled process conversion rates of ca. 85% were obtained with substrate
solutions containing 10% PPO by using only slight excesses of the amino
donors glutamate and aspartate. The contamination of the reaction broth
with amino acid by-products was < 3%.
Copyright © 1996, American Society for Microbiology
Stereospecific production of the herbicide phosphinothricin (glufosinate): purification of aspartate transaminase from Bacillus stearothermophilus, cloning of the corresponding gene, aspC, and application in a coupled transaminase process
Hoechst Schering AgrEvo GmbH, Frankfurt, Germany.
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