|
type |
Journal Article |
authors |
Laue, H; Cook, A.M. |
title |
Biochemical and molecular characterization of taurine:pyruvate aminotransferase from the anaerobe Bilophila wadsworthia |
journal |
Eur J Biochem |
Activity |
2.6.1.77 |
Family |
2.6.1.77 |
sel |
selected |
ui |
11082195 |
year |
(2000) |
volume |
267 |
number |
23 |
pages |
6841-8 |
| |
abstract |
Bilophila wadsworthia RZATAU is a Gram-negative bacterium which converts the sulfonate taurine (2-aminoethanesulfonate) to ammonia, acetate and sulfide in an anaerobic respiration. Taurine:pyruvate aminotransferase (Tpa) catalyses the initial metabolic reaction yielding alanine and sulfoacetaldehyde. We purified Tpa 72-fold to apparent homogeneity with an overall yield of 89%. The purified enzyme did not require addition of pyridoxal 5'-phosphate, but highly active enzyme was only obtained by addition of pyridoxal 5'-phosphate to all buffers during purification. SDS/PAGE revealed a single protein band with a molecular mass of 51 kDa. The apparent molecular mass of the native enzyme was 197 kDa as determined by gel filtration, which indicates a homotetrameric structure. The kinetic constants for taurine were: Km = 7.1 mM, Vmax = 1.20 nmol.s-1, and for pyruvate: Km = 0.82 mM, Vmax = 0.17 nmol.s-1. The purified enzyme was able to transaminate hypotaurine (2-aminosulfinate), taurine, beta-alanine and with low activity cysteine and 3-aminopropanesulfonate. In addition to pyruvate, 2-ketobutyrate and oxaloacetate were utilized as amino group acceptors. We have sequenced the encoding gene (tpa). It encoded a 50-kDa peptide, which revealed 33% identity to diaminopelargonate aminotransferase from Bacillus subtilis. |
last changed |
2009/05/19 17:46 |
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