Zeng Jia, Deng Senwen, Wang Yiping
School of Life Science, Hunan University of Science and Technology, Xiangtan, Hunan, 411201, People's Republic of China.
Key Laboratory of Ecological Remediation and Safe Utilization of Heavy Metal-Polluted Soils, College of Hunan Province, Xiangtan, 411201, Hunan, People's Republic of China.
Appl Biochem Biotechnol. 2017 Jul;182(3):1198-1207. doi: 10.1007/s12010-016-2392-1. Epub 2017 Jan 13.
Acyl-CoA dehydrogenase 9 (ACAD 9) is the ninth member of ACADs involved in mitochondrial fatty acid oxidation and possibly complex I assembly. Sequence alignment suggested that Glu389 of rat ACAD 9 was highly conserved and located near the active center and might act as an important base for the dehydrogenation reaction. The role of Glu389 in the catalytic reaction was investigated by site-directed mutagenesis. Both wild-type and mutant ACAD 9 proteins were purified and their catalytic characterization was studied. When Glu389 was replaced by other residues, the enzyme activity could be lost to a large extent. Those results suggested that Glu389 could function as the catalytic base that abstracted the α-proton of the acyl-CoA substrate in a proposed catalytic mechanism.
酰基辅酶A脱氢酶9（ACAD 9）是参与线粒体脂肪酸氧化以及可能参与复合体I组装的酰基辅酶A脱氢酶家族中的第九个成员。序列比对表明，大鼠ACAD 9的Glu389高度保守，位于活性中心附近，可能作为脱氢反应的重要碱基。通过定点诱变研究了Glu389在催化反应中的作用。对野生型和突变型ACAD 9蛋白均进行了纯化，并研究了它们的催化特性。当Glu389被其他残基取代时，酶活性可能会在很大程度上丧失。这些结果表明，在提出的催化机制中，Glu389可作为催化碱基提取酰基辅酶A底物的α-质子。
