Subcellular distribution of alanine aminotransferase activity in maize (Zea mays L.) leaves |
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Authors: | Sławomir Orzechowski Joanna Socha-Hanc Andrzej Paszkowski |
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Institution: | (1) Department of Biochemistry, Faculty of Agriculture Warsaw Agricultural University, Rakowiecka 26/30, 02-528 Warszawa, Poland |
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Abstract: | The intracellular distribution of alanine aminotransferase (AlaAT, EC 2.6.1.2) activity with L-alanine and 2-oxoglutarate
as a substrates in maize whole leaf extract and bundle sheath cells was studied. After isolation of the mitochondrial-peroxisomal
fraction, mitochondria and peroxisomes were separated by centrifugation on a linear 40–52 % (w/w) sucrose gradient. L-Alanine-2-oxoglutarate
transaminating activity of whole leaf extract showed two peaks: first distinctly higher associated with mitochondria and second
lower with peroxisomes. In bundle sheath cells only one peak of this activity was found. It corresponded to the mitochondrial
region of the gradient. It is proposed that mitochondrial L-alanine — 2-oxoglutarate activity was brought about by AlaAT.
Glycine aminotransferase (EC 2.6.1.4) could be responsible for the same activity in peroxisomes.
This work was supported by the State Committee for Scientific Research, a grant No. 5PO6A00510 |
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Keywords: | alanine aminotransferase L-alanine — 2-oxoglutarate activity glycine aminotransferase subcellular distribution |
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