Synthesis and inhibition mechanism of Δlac-acetogenins, a novel type of inhibitor of bovine heart mitochondrial complex I
Synthesis and inhibition mechanism of Δlac-acetogenins, a novel type of inhibitor of bovine heart mitochondrial complex I
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DOI：
10.1021/bi0479003
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发表时间：
2005-01-18
期刊：
影响因子：
2.9
通讯作者：
Miyoshi, H
中科院分区：
文献类型：
--
作者：
Ichimaru, N;Murai, M;Miyoshi, H
我们已经合成了Delta 1ac-乙酸配基，其是新的乙酸配基模拟物，具有两个N-烷基尾而没有α，β-不饱和γ-内酯环，并表明它们的抑制机制可能不同于普通的乙酸配基[Hamada等人（2004）Biochemistry 43，3651-3658]。为了更详细地阐明Delta 1ac-乙酸配基的抑制机制，我们对原始Delta 1ac-乙酸配基进行了广泛的结构修饰，并表征了牛心脏线粒体复合物I的抑制作用。与常见的乙酸配基相反，相邻的双-THF环的存在和羟基化的双-THF环周围的立体化学是有效抑制所需的重要结构因素。具有正丁基苯基醚结构的衍生物（化合物7）的抑制效力似乎上级于原始Delta 1 ac-乙酸配基的抑制效力，并且与最有效的天然乙酸配基之一的布拉他辛（bullatacin）的抑制效力相当。稳态复合物I活性的双抑制剂滴定显示化合物7和布拉他辛的抑制程度不是相加的，这表明两种抑制剂的结合位点是不相同的。使用荧光配体的竞争测试表明，化合物7的结合位点不与其他复合物I抑制剂的结合位点重叠。化合物7对复合物I产生超氧化物的影响也不同于其他复合物I抑制剂。我们的研究结果清楚地表明，Delta 1ac-acetogenins是一种新型的抑制剂，作用于牛复合物I的末端电子转移步骤。
We have synthesized Delta1ac-acetogenins that are new acetogenin mimics possessing two n-alkyl tails without an alpha,beta-unsaturated gamma-lactone ring and suggested that their inhibition mechanism may be different from that of common acetogenins [Hamada et al. (2004) Biochemistry 43, 3651-3658]. To elucidate the inhibition mechanism of Delta1ac-acetogenins in more detail, we carried out wide structural modifications of original Delta1ac-acetogenins and characterized the inhibitory action with bovine heart mitochondrial complex I. In contrast to common acetogenins, both the presence of adjacent bis-THF rings and the stereochemistry around the hydroxylated bis-THF rings are important structural factors required for potent inhibition. The inhibitory potency of a derivative possessing an n-butylphenyl ether structure (compound 7) appeared to be superior to that of the original Delta1ac-acetogenins and equivalent to that of bullatacin, one of the most potent natural acetogenins. Double-inhibitor titration of steady-state complex I activity showed that the extent of inhibition of compound 7 and bullatacin is not additive, suggesting that the binding sites of the two inhibitors are not identical. Competition tests using a fluorescent ligand indicated that the binding site of compound 7 does not overlap with that of other complex I inhibitors. The effects of compound 7 on superoxide production from complex I are also different from those of other complex I inhibitors. Our results clearly demonstrate that Delta1ac-acetogenins are a novel type of inhibitor acting at the terminal electron-transfer step of bovine complex I.