|
type |
Journal Article |
authors |
Orzechowski, S.; Socha-Hanc, J.; Paszkowski, A. |
title |
Alanine aminotransferase and glycine aminotransferase from maize (Zea mays L.) leaves |
journal |
Acta Biochim Pol |
Activity |
2.6.1.4 |
ui |
20012535 |
year |
(1999) |
volume |
46 |
number |
2 |
pages |
447-57 |
| |
keywords |
Alanine Transaminase/chemistry/isolation & purification/*metabolism |
abstract |
Alanine aminotransferase (AlaAT, EC 2.6.1.2) and glycine aminotransferase (GlyAT, EC 2.6.1.4), two different enzymes catalyzing transamination reactions with L-alanine as the amino-acid substrate, were examined in maize in which alanine participates substantially in nitrogen transport. Preparative PAGE of a partially purified preparation of aminotransferases from maize leaves gave 6 fractions differing in electrophoretic mobility. The fastest migrating fraction I represents AlaAT specific for L-alanine as amino donor and 2- oxoglutarate as amino acceptor. The remaining fractions showed three aminotransferase activities: L-alanine-2-oxoglutarate, L-alanine- glyoxylate and L-glutamate-glyoxylate. By means of molecular sieving on Zorbax SE-250 two groups of enzymes were distinguished in the PAGE fractions: of about 100 kDa and 50 kDa. Molecular mass of 104 kDa was ascribed to AlaAT in fraction I, while the molecular mass of the three enzymatic activities in 3 fractions of the low electrophoretic mobility was about 50 kDa. The response of these fractions to: aminooxyacetate, 3-chloro-L-alanine and competing amino acids prompted us to suggest that five out of the six preparative PAGE fractions represented GlyAT isoforms, differing from each other by the L-glutamate-glyoxylate:L- alanine-glyoxylate:L-alanine-2-oxoglutarate activity ratio. |
last changed |
2002/11/12 16:17 |
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