|
type |
Journal Article |
authors |
Dumora, C.; Lacoste, A. M.; Cassaigne, A. |
title |
Purification and properties of 2-aminoethylphosphonate:pyruvate aminotransferase from Pseudomonas aeruginosa |
journal |
Eur J Biochem |
Activity |
2.6.1.37 |
ui |
83209625 |
year |
(1983) |
volume |
133 |
number |
1 |
pages |
119-25. |
| |
keywords |
Hydrogen-Ion Concentration |
abstract |
2-Aminoethylphosphonate aminotransferase has been purified to homogeneity with a yield of 15% from cell extracts of Pseudomonas aeruginosa. The molecular weight of the enzyme was estimated by gel filtration to be 65000 +/- 2000. Sodium dodecyl sulfate/polyacrylamide gel electrophoresis yielded a molecular weight of 16500 +/- 1000, suggesting a tetrameric model for this protein. The absorption spectrum exhibits maxima at 280 nm, 335 nm and 415 nm which are characteristic of a pyridoxal-phosphate-dependent enzyme: 4 mol of pyridoxal 5'- phosphate/mol of enzyme have been found. This aminotransferase catalyzes the transfer of the amino group of 2-aminoethylphosphonate (ciliatine) to pyruvate to give 2-phosphonoacetaldehyde and alanine. A pH optimum between 8.5-9 and an activity increasing from 30 degrees C to 50 degrees C have been observed. The reaction follows Michaelis- Menten kinetics with Km values of 3.85 mM and 3.5 mM for ciliatine and pyruvate respectively. This enzyme shows a very high specificity since ciliatine and pyruvate are the only amino donor and acceptor respectively. Methyl, ethyl and propylphosphonic acids are better competitors towards ciliatine than their alpha-amino derivatives. 3- Aminopropylphosphonate, the higher homologue of ciliatine, is recognized neither as a substrate nor as an inhibitor. The enzyme activity is significantly affected by carbonyl reagents and by HgCl2. Transamination of 2-aminoethylphosphonate is the first step of a double- step pathway which leads to the cleavage of its C-P bond. |
last changed |
2002/11/12 16:17 |
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