REGULATION OF GLUTAMATE-DEHYDROGENASE BY PALMITOYL-COENZYME A
REGULATION OF GLUTAMATE-DEHYDROGENASE BY PALMITOYL-COENZYME A
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DOI：
10.1016/0003-9861(81)90364-7
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发表时间：
1981-01-01
影响因子：
3.9
通讯作者：
KMIOTEK, E
中科院分区：
文献类型：
--
作者：
FAHIEN, LA;KMIOTEK, E
当TPNH而不是DPNH作为辅酶时，谷氨酸脱氢酶[牛肝线粒体素]被棕榈酰辅酶A抑制得更多。抑制作用进一步被α-酮戊二酸和苹果酸。因此，例如，在TPNH加苹果酸存在下，50%抑制所需的棕榈酰-CoA的量比先前报道的用DPNH作为辅酶获得的值低10倍（0.03 μ M）。变构调节剂如ATP、GTP和亮氨酸减少棕榈酰辅酶A对谷氨酸脱氢酶的抑制。棕榈酰辅酶A和ADP具有竞争性。因此，棕榈酰辅酶A结合位点显然在这些变构修饰剂的位点附近，并且可能在ADP位点。ADP（其仅具有1个位点/多肽链）可以完全防止棕榈酰-CoA的抑制的事实表明，每个多肽链仅存在1个动力学显著的棕榈酰-CoA结合位点。这与每个多肽链添加1当量棕榈酰辅酶A抑制约80%的事实一致。谷氨酸脱氢酶对棕榈酰辅酶A的高亲和力使其能够成功地与其他线粒体蛋白竞争棕榈酰辅酶A。
Glutamate dehydrogenase [bovine liver mitochondrin] is inhibited more by palmitoyl-CoA when TPNH instead of DPNH is the coenzyme. Inhibition is further enhanced by .alpha.-ketoglutarate and malate. Thus, for example, in the presence of TPNH plus malate, the amount of palmitoyl-CoA required for 50% inhibition is 10-fold lower (0.03 .mu.M) than previously reported values obtained with DPNH as a coenzyme. Allosteric modifiers such as ATP, GTP and leucine decrease inhibition of glutamate dehydrogenase by palmitoyl-CoA. Palmitoyl-CoA and ADP are competitive. Thus, the palmitoyl-CoA binding site is apparently in the vicinity of the site of these allosteric modifiers and is probably at the ADP site. The fact that ADP (which has only 1 site/polypeptide chain) can completely prevent inhibition by palmitoyl-CoA suggests that there is only 1 kinetically significant palmitoyl-CoA binding site per polypeptide chain. This is consistent with the fact that adding 1 equivalent of palmitoyl-CoA per polypeptide chain inhibits about 80%. The high affinity of glutamate dehydrogenase for palmitoyl-CoA enables it to successfully compete with other mitochondrial proteins for palmitoyl-CoA.