Allosteric inhibition of human liver aldehyde dehydrogenase by the isoflavone prunetin.
Allosteric inhibition of human liver aldehyde dehydrogenase by the isoflavone prunetin.
复制标题
异黄酮普鲁丁对人肝醛脱氢酶的变构抑制。
DOI：
10.1016/s0006-2952(96)00837-4
复制
发表时间：
1997
影响因子：
5.8
通讯作者：
Weiner,H
中科院分区：
文献类型：
--
作者：
Sheikh,S;Weiner,H
包括普鲁丁（4',5-二羟基-7-甲氧基异黄酮）在内的异黄酮衍生物被证明是人醛脱氢酶的有效抑制剂（Keung W-M 和 Vallee BL, Proc Nad Acad Sci USA 90: 1247–1251, 1993）。使用重组表达的人醛脱氢酶重新研究抑制反应。动力学分析表明，Prunetin 与线粒体和细胞质酶竞争性抑制 NAD 和丙醛。线粒体酶的 Ki 值远低于细胞质酶的 Ki 值。在 Mg2+ 存在的情况下，线粒体酶获得了混合的抑制模式。每摩尔四聚体线粒体酶仅结合一摩尔普鲁丁，在 Mg2+ 存在下保持不变。普鲁内丁没有从酶-NADH 复合物中取代 NADH。丙醛不能逆转由于酶普鲁汀复合物形成而获得的荧光损失，这表明普鲁汀可能不会在底物位点相互作用。线粒体酶的酯酶活性也被普鲁丁以竞争性方式抑制。与天然酶相比，用谷氨酰胺替换赖氨酸 192 产生了具有 20% Kcar 和 Kmfor NAD 增加 100 倍的突变体。然而，普鲁丁素针对 NAD 的 Ki 值与用天然酶观察到的相似。即使浓度非常高，普鲁内丁也不是酒精和苹果酸脱氢酶的抑制剂。结论是普鲁丁可能作为乙醛脱氢酶的变构抑制剂。
Isoflavonoid derivatives including prunetin (4′,5-dihydroxy-7-methoxyisoflavone) were shown to be potent inhibitors of human aldehyde dehydrogenases (Keung W-M and Vallee BL, Proc Nad Acad Sci USA 90: 1247–1251, 1993). The inhibition reaction was reinvestigated using recombinantly expressed human aldehyde dehydrogenases. The kinetic analyses showed that prunetin inhibits competitively against both NAD and propionaldehyde with the mitochondrial and cytoplasmic enzymes. The Kivalue for the mitochondrial enzyme was much lower than for the cytoplasmic enzyme. A mixed pattern of inhibition was obtained with the mitochondrial enzyme in the presence of Mg2+. Only one mole of prunetin binds per mole of tetrameric mitochondrial enzyme, which remains unaltered in the presence of Mg2+. Prunetin did not displace NADH from the enzyme-NADH complex. Propionaldehyde did not reverse the loss of fluorescence obtained due to enzymeprunetin complex formation, indicating that prunetin may not be interacting at the substrate site. The esterase activity of the mitochondrial enzyme was also inhibited by prunetin in a competitive manner. The replacement of lysine 192 by glutamine resulted in a mutant with a 20% Kcarand a 100-fold increase in the Kmfor NAD compared with the native enzyme. However, the Kivalue of prunetin against NAD was similar to that observed with the native enzyme. Prunetin, even at a very high concentration, was not an inhibitor of alcohol and malate dehydrogenase. It was concluded that prunetin may act as an allosteric inhibitor of aldehyde dehydrogenase.