[Stability of aspartate aminotransferases in Lupinus albus L. cv Estoril leaves in unpurified extracts]
1997
Martins, L.L. | Mourato, M.P. | Girio, F.M. | Varennes, A. de
Aspartate aminotransferase (AAT: L-aspartate; 2-oxoglutarate aminotransferase, EC 2.6.1.1) catalyses the reversible reaction: aspartate + 2-oxoglutarate - glutamate + oxaloacetate. Four AAT isoenzymes are usually present in white lupin leaves (Lupinus albus L. cv Estoril) and can be detected by polyacrylamide gel electrophoresis (PAGE). In this work we studied the AAT extraction conditions and the variation of enzymatic activity with temperature and with seedlings age (up to 30 days). THe optimal pH for enzymatic activity was determined. Studies were also performed on the stability of the extract at - 20°C and with 20% glycerol, 5 mM DTT, 5 mM 2-mercaptoethanol and 5 mM EDTA, at 4°C
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