PMID:2178550
| Citation |
Schulz, A, Taggeselle, P, Tripier, D and Bartsch, K (1990) Stereospecific production of the herbicide phosphinothricin (glufosinate) by transamination: isolation and characterization of a phosphinothricin-specific transaminase from Escherichia coli. Appl. Environ. Microbiol. 56:1-6 |
|---|---|
| Abstract |
An aminotransferase capable of transaminating 2-oxo-4-[(hydroxy)(methyl)phosphinoyl]butyric acid to L-phosphinothricin [L-homoalanine-4-yl-(methyl)phosphinic acid], the active ingredient of the herbicide Basta (Hoechst AG), was purified to apparent homogeneity from Escherichia coli K-12. The enzyme catalyzes the transamination of L-phosphinothricin and various analogs with 2-ketoglutarate as the amino group acceptor. The transaminase has a molecular mass of 43 kilodaltons by sodium dodecyl sulfate-gel analysis and an isoelectric point of 4.35. The enzyme was most active in the high-pH region, with a maximum at pH 8.0 to 9.5, and had a temperature optimum of 55 degrees C. Heat stability was observed up to 70 degrees C. Substrate specificity studies suggested that the enzyme is identical with the 4-aminobutyrate:2-ketoglutarate transaminase (EC 2.6.1.19). The first 30 amino acids of the N terminus of the protein were determined by gas phase sequencing. The transaminase was immobilized by coupling to the epoxy-activated carrier VA-Biosynth (Riedel de Haen) and used in a column reactor for the continuous production of L-phosphinothricin. The enzyme reactor was operated for 7 weeks with only a slight loss of catalytic capacity. Production rates of more than 50 g of L-phosphinothricin per liter of column per h were obtained. |
| Links | |
| Keywords |
Aminobutyrates/isolation & purification; Aminobutyrates/metabolism; Chromatography, Ion Exchange; Electrophoresis, Polyacrylamide Gel; Escherichia coli/enzymology; Hydrogen-Ion Concentration; Isoelectric Focusing; Ketoglutaric Acids/metabolism; Molecular Structure; Substrate Specificity; Temperature; Transaminases/analysis; Transaminases/isolation & purification; Transaminases/metabolism; gamma-Aminobutyric Acid/metabolism |
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