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首页> 外文期刊>Acta crystallographica.Section D. Biological crystallography >The structures of Alcaligenes faecalis D-3-hydroxybutyrate dehydrogenase before and after NAD+ and acetate binding suggest a dynamical reaction mechanism as a member of the SDR family.
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The structures of Alcaligenes faecalis D-3-hydroxybutyrate dehydrogenase before and after NAD+ and acetate binding suggest a dynamical reaction mechanism as a member of the SDR family.

机译：粪产碱杆菌属的结构D-3-hydroxybutyrate脱氢酶,乙酸在NAD +和约束力的建议动力反应机理的一员特别提款权的家庭。

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摘要

D-3-Hydroxybutyrate dehydrogenase, which catalyzes the reversible reaction between D-3-hydroxybutyrate and acetoacetate, has been classified into the short-chain dehydrogenase/reductase family and is a useful marker in the assay of diabetes mellitus and/or ketoacidosis. The enzyme from Alcaligenes faecalis was crystallized in the apo form and in the holo form with acetate as a substrate analogue. The crystal structures of both forms were determined at 2.2 angstroms resolution. The enzyme is a tetramer composed of four subunits assembled with noncrystallographic 222 point symmetry. Each subunit has two domains. The principal domain adopts the Rossmann fold essential for nucleotide binding, which is a common feature of the SDR family. NAD+ is bound in a large cleft in the domain. The pyrophosphate group of NAD+ is covered by the small additional domain, which is supported by two extended arms allowing domain movement. In the catalytic site, a water molecule is trapped by the catalytic Tyr155 and Ser142 residues in the vicinity of the bound NAD+ and acetate. The substrate analogue acetate is bound above the nicotinamide plane. A substrate (D-3-hydroxybutylate) bound model can reasonably be constructed by adding two C atoms into the void space between the water O atom and the methyl group of the acetate, suggesting a substrate-bound state before enzymatic reaction occurs. Based on these structural features, a reaction mechanism has been proposed.
机译：D-3-Hydroxybutyrate脱氢酶,它催化之间的可逆反应D-3-hydroxybutyrate和乙酰乙酸盐分为短链脱氢酶/还原酶家族,是一个有用的标记在糖尿病和/或试验酮症酸中毒。粪在形式和人群的结晶以乙酸为底物的整体形式模拟。确定为2.2埃分辨率。酶是由四个亚基组成的四聚物组装noncrystallographic 222点对称。主域采用罗斯曼褶皱对于核苷酸结合,这是一个特别提款权家族的共同特征。在一个大裂口的域。群NAD +被小额外的覆盖域,这是由两个怀里允许域运动。一个水分子被催化Tyr155和Ser142残留物附近的绑定NAD +和醋酸。醋酸必然高于烟酰胺平面。衬底(D-3-hydroxybutylate)模型通过添加两个C原子合理构建到水O原子之间的孔隙空间的甲基乙酸,暗示之前substrate-bound状态酶反应发生。提出了反应机理。

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