New Zealand Journal of Crop and Horticultural Science abstracts
Short communication
Improved procedures for extraction of lysine 2-oxoglutarate reductase/saccharopine
dehydrogenase (LOR/SDH) enzyme from Phaseolus vulgaris cultivars
S. T. Cunha Lima1*
R. A. Azevedo2
L. G. Santoro1
1Departamento de Fisiologia Vegetal
Instituto de Biologia
Universidade Estadual de Campinas
Campinas, SP CEP 13083-970
Brasil
2Departamento de Genética
Escola Superior de Agricultura
Luiz de Queiroz Universidade de São Paulo
Piracicaba, SP CEP 13400-970
Brasil
*Present address: Diabetes Center, University of California San Francisco
(UCSF),
513 Parnassus Avenue, Health Science Building, Room 1119,
San Francisco, CA 94146-0504, United States.
email: slima@diabetes.ucsf.edu
Abstract Lysine is one of the most limiting essential
amino acid in food crops consumed by humans. Excess lysine is catabolised
via saccharopine by two consecutive enzymes, lysine 2-oxoglutarate reductase
(LOR) and saccharopine dehydrogenase (SDH), linked on a single bifunctional
polypeptide. The activities of LOR and SDH were shown to be similar in three
distinct Phaseolus vulgaris cultivars. The addition of bovine serum
albumin (BSA) to buffers resulted in different responses among the crude,
0-7.5%, and 7.5-15% polyethylene glycol (PEG) 8000 extracts. Different responses
were also observed when the activities of LOR and SDH were tested after extraction
in the presence of phosphatase inhibitors. The addition of lysine to the growth
medium increased the activity of LOR, but not SDH. The results observed add
new information on the regulation of LOR/SDH in a legume plant species.
Keywords Phaseolus vulgaris; lysine; lysine 2-oxoglutarate
reductase; saccharopine dehydrogenase
H02074 Received 18 September 2002; accepted 22 April 2003; published 8
August 2003
New Zealand Journal of Crop and Horticultural Science, 2003, Vol. 31:
261-268
0014-0671/03/3103-0261 $7.00 © The Royal Society of New Zealand
2003
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