TY - JOUR
T1 - Characteristics of glutamate dehydrogenase in mitochondria prepared from corn shoots
AU - Yamaya, Tomoyuki
AU - Oaks, Ann
AU - Matsumoto, Hideaki
N1 - Publisher Copyright:
© 1984 American Society of Plant Biologists. All rights reserved.
PY - 1984
Y1 - 1984
N2 - The amination of a-ketoglutarate (α-KG) by NADH-glutamate dehydrogenase (GDH) obtained from Sephadex G-75 treated crude extracts from shoots of 5-day-old seedlings was stimulated by the addition of Ca2+. The NADH-GDH purified 161-fold with ammonium sulfate, DEAE-Toyopearl, and Sephadex G-200 was also activated by Ca2+ in the presence of 160 micromolar NADH. However, with 10 micromolar NADH, Ca2+ had no effect on the NADH-GDH activity. The deamination reaction (NAD-GDH) was not influenced by the addition of Ca2+. About 25% of the NADH-GDH activity was solubilized from purified mitochondria after a simple osmotic shock treatment, whereas the remaining 75% of the activity was associated with the mitochondrial membrane fraction. When the lysed mitochondria, mitochondrial matrix, or mitochondrial membrane fraction was used as the source of NADHGDH, Ca2+ had little effect on its activity. The mitochondrial fraction contained about 155 nanomoles Ca per milligram of mitochondrial protein, suggesting that the NADH-GDH in the mitochondria is already in an activated form with regard Ca2+. In a simulated in vitro system using concentrations of 6A millimolar NAD, 0.21 millimolar NADH, 5 millimolar α-KG, and 5 millimolar glutamate thought to occur in the mitochondria, together with 1 millimolar Ca2+, 10 and 50 millimolar NH4+, and purified enzyme, the equilibrium of GDH was in the direction of glutamate formation.
AB - The amination of a-ketoglutarate (α-KG) by NADH-glutamate dehydrogenase (GDH) obtained from Sephadex G-75 treated crude extracts from shoots of 5-day-old seedlings was stimulated by the addition of Ca2+. The NADH-GDH purified 161-fold with ammonium sulfate, DEAE-Toyopearl, and Sephadex G-200 was also activated by Ca2+ in the presence of 160 micromolar NADH. However, with 10 micromolar NADH, Ca2+ had no effect on the NADH-GDH activity. The deamination reaction (NAD-GDH) was not influenced by the addition of Ca2+. About 25% of the NADH-GDH activity was solubilized from purified mitochondria after a simple osmotic shock treatment, whereas the remaining 75% of the activity was associated with the mitochondrial membrane fraction. When the lysed mitochondria, mitochondrial matrix, or mitochondrial membrane fraction was used as the source of NADHGDH, Ca2+ had little effect on its activity. The mitochondrial fraction contained about 155 nanomoles Ca per milligram of mitochondrial protein, suggesting that the NADH-GDH in the mitochondria is already in an activated form with regard Ca2+. In a simulated in vitro system using concentrations of 6A millimolar NAD, 0.21 millimolar NADH, 5 millimolar α-KG, and 5 millimolar glutamate thought to occur in the mitochondria, together with 1 millimolar Ca2+, 10 and 50 millimolar NH4+, and purified enzyme, the equilibrium of GDH was in the direction of glutamate formation.
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U2 - 10.1104/pp.76.4.1009
DO - 10.1104/pp.76.4.1009
M3 - Article
AN - SCOPUS:84950014120
VL - 76
SP - 1009
EP - 1013
JO - Plant Physiology
JF - Plant Physiology
SN - 0032-0889
IS - 4
ER -