TY - JOUR
T1 - The isozymic nature and kinetic properties of glutamate dehydrogenase from safflower seedlings
AU - Errel, A.
AU - Mor, Henia
AU - Barash, I.
PY - 1973/2
Y1 - 1973/2
N2 - Levels of glutamate dehydrogenase (GDH) [L-glutamate: NAD oxidoreductase (deaminating), EC 1.4.1.2] from safflower roots and cotyledons increased (×2.7) and decreased ( ×5.7), respectively, as a function of seedling age. No significant changes in enzyme levels were detected during hypocotyl development. GDH preparations of the different organs were resolved by polyacrylamide gel electrophoresis into 2 to 4 isozymes. The isozymic pattern was influenced by seedling age and organ tested. The slowest moving isozyme (No. 1) appears to be responsible for the changes in GDH levels observed in cotyledons and roots. We isolated isozyme 1 and GDH fraction chiefly containingisozyme 2, by DEAE-cellulose chromatography.GDH was purified approximately 53-fold from the particulate fraction of cotyledons. The pH optima for NADH and NAD activities were 8.2 and 8.9, respectively. Michaelis constants were found to be: α-ketoglutarate, 8mM; glutamate, 4 mM; ammonium, 35.4 mM; NAD, 0.26 mM; NADH, 0.065 mM. Km values of isozymes 1 and 2 were similar. The binding order of substrates in die reductive amination reaction was NADH, α-ketoglutarate and NH4+.
AB - Levels of glutamate dehydrogenase (GDH) [L-glutamate: NAD oxidoreductase (deaminating), EC 1.4.1.2] from safflower roots and cotyledons increased (×2.7) and decreased ( ×5.7), respectively, as a function of seedling age. No significant changes in enzyme levels were detected during hypocotyl development. GDH preparations of the different organs were resolved by polyacrylamide gel electrophoresis into 2 to 4 isozymes. The isozymic pattern was influenced by seedling age and organ tested. The slowest moving isozyme (No. 1) appears to be responsible for the changes in GDH levels observed in cotyledons and roots. We isolated isozyme 1 and GDH fraction chiefly containingisozyme 2, by DEAE-cellulose chromatography.GDH was purified approximately 53-fold from the particulate fraction of cotyledons. The pH optima for NADH and NAD activities were 8.2 and 8.9, respectively. Michaelis constants were found to be: α-ketoglutarate, 8mM; glutamate, 4 mM; ammonium, 35.4 mM; NAD, 0.26 mM; NADH, 0.065 mM. Km values of isozymes 1 and 2 were similar. The binding order of substrates in die reductive amination reaction was NADH, α-ketoglutarate and NH4+.
UR - http://www.scopus.com/inward/record.url?scp=0344730417&partnerID=8YFLogxK
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AN - SCOPUS:0344730417
SN - 0032-0781
VL - 14
SP - 39
EP - 50
JO - Plant and Cell Physiology
JF - Plant and Cell Physiology
IS - 1
ER -