Li Shu Jie, Umena Yasufumi, Yorita Kazuko, Matsuoka Takeshi, Kita Akiko, Fukui Kiyoshi, Morimoto Yukio
Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan.
Biochem Biophys Res Commun. 2007 Jul 13;358(4):1002-7. doi: 10.1016/j.bbrc.2007.05.021. Epub 2007 May 11.
L-Lactate oxidase (LOX) from Aerococcus viridans catalyzes the oxidation of L-lactate to pyruvate by the molecular oxygen and belongs to a large family of 2-hydroxy acid-dependent flavoenzymes. To investigate the interaction of LOX with pyruvate in structural details and understand the chemical mechanism of flavin-dependent L-lactate dehydrogenation, the LOX-pyruvate complex was crystallized and the crystal structure of the complex has been solved at a resolution of 1.90 Angstrom. One pyruvate molecule bound to the active site and located near N5 position of FMN for subunits, A, B, and D in the asymmetric unit, were identified. The pyruvate molecule is stabilized by the interaction of its carboxylate group with the side-chain atoms of Tyr40, Arg181, His265, and Arg268, and of its keto-oxygen atom with the side-chain atoms of Tyr146, Tyr215, and His265. The alpha-carbon of pyruvate is found to be 3.13 Angstrom from the N5 atom of FMN at an angle of 105.4 degrees from the flavin N5-N10 axis.
来自绿色气球菌的L-乳酸氧化酶（LOX）催化L-乳酸被分子氧氧化为丙酮酸，属于一个依赖2-羟基酸的黄素酶大家族。为了从结构细节上研究LOX与丙酮酸的相互作用，并了解黄素依赖性L-乳酸脱氢的化学机制，使LOX-丙酮酸复合物结晶，并以1.90埃的分辨率解析了该复合物的晶体结构。在不对称单元中，鉴定出一个与活性位点结合且位于FMN的N5位置附近的丙酮酸分子，该分子存在于亚基A、B和D中。丙酮酸分子通过其羧基与Tyr40、Arg181、His265和Arg268的侧链原子相互作用，以及其酮氧原子与Tyr146、Tyr215和His265的侧链原子相互作用而得以稳定。发现丙酮酸的α-碳原子距离FMN的N5原子3.13埃，与黄素N5-N10轴呈105.4度角。
