Zn2+ inhibits α-ketoglutarate-stimulated mitochondrial respiration and the isolated α-ketoglutarate dehydrogenase complex
Zn2+ inhibits α-ketoglutarate-stimulated mitochondrial respiration and the isolated α-ketoglutarate dehydrogenase complex
复制标题
DOI：
10.1074/jbc.275.18.13441
复制
发表时间：
2000-05-05
影响因子：
4.8
通讯作者：
Cooper, AJL
中科院分区：
文献类型：
--
作者：
Brown, AM;Kristal, BS;Cooper, AJL
细胞内游离Zn2+在多种病理条件下升高，包括缺血再灌注损伤和阿尔茨海默病。线粒体呼吸损伤也与这些病理状况有关。为了验证Zn2+升高与呼吸损伤之间是否存在联系，我们在加入Zn2+后，测量了离体大鼠肝脏线粒体的呼吸作用。在培养的肝细胞中，当α -酮戊二酸盐的浓度在细胞内Zn2+的范围内时，观察到Zn2+对呼吸的抑制作用（K-i(app) = 1 μ M）， Zn2+可以抑制be复合物(Link， T， A, and von Jagow， G, (1995) J. Biol。然而，琥珀酸盐（K-i(app) =类似于6 μ M）刺激的呼吸对Zn2+不太敏感，这表明在bc(1)复合体上游存在Zn2+的线粒体靶点。纯化的猪心脏铜酮戊二酸脱氢酶复合物被Zn2+强烈抑制（K-i(app) = 0.37 +/- 0.05 μ M）。谷氨酸脱氢酶抗性较强（K-i(app) = 6 μ M），苹果酸脱氢酶不受影响，琥珀酸脱氢酶受Zn2+刺激，Zn2+抑制α -酮戊二酸脱氢酶复合体需要酶循环，EDTA可以逆转。可逆性与暴露时间和Zn2+浓度呈负相关。生理性游离Zn2+可能通过可逆抑制α -酮戊二酸脱氢酶复合体来调节肝脏线粒体呼吸。相反，细胞内Zn2+的极端或慢性升高可能导致线粒体呼吸的持续减少，这在富含Zn2+的病变组织中已经观察到。
Intracellular free Zn2+ is elevated in a variety of pathological conditions, including ischemia-reperfusion injury and Alzheimer's disease. Impairment of mitochondrial respiration is also associated with these pathological conditions. To test whether elevated Zn2+ and impaired respiration might be linked, respiration of isolated rat liver mitochondria was measured after addition of Zn2+. Zn2+ inhibition (K-i(app) = similar to 1 mu M) was observed for respiration stimulated by alpha-ketoglutarate at concentrations well within the range of intracellular Zn2+ reported for cultured hepatocytes, The be, complex is inhibited by Zn2+ (Link, T, A, and von Jagow, G, (1995) J. Biol. Chem, 270, 25001-25006), However, respiration stimulated by succinate (K-i(app) = similar to 6 mu M) was less sensitive to Zn2+, indicating the existence of a mitochondrial target for Zn2+ upstream from bc(1) complex. Purified pig heart cu-ketoglutarate dehydrogenase complex was strongly inhibited by Zn2+ (K-i(app) = 0 37 +/- 0.05 mu M). Glutamate dehydrogenase was more resistant (K-i(app) = 6 mu M), malate dehydrogenase was unaffected, and succinate dehydrogenase was stimulated by Zn2+, Zn2+ inhibition of alpha-ketoglutarate dehydrogenase complex required enzyme cycling and was reversed by EDTA. Reversibility was inversely related to the duration of exposure and the concentration of Zn2+. Physiological free Zn2+ may modulate hepatic mitochondrial respiration by reversible inhibition of the alpha-ketoglutarate dehydrogenase complex. In contrast, extreme or chronic elevation of intracellular Zn2+ could contribute to persistent reductions in mitochondrial respiration that have been observed in Zn2+-rich diseased tissues.