Johansson K, El-Ahmad M, Ramaswamy S, Hjelmqvist L, Jörnvall H, Eklund H
Department of Molecular Biology, Swedish University of Agricultural Sciences, Uppsala.
Protein Sci. 1998 Oct;7(10):2106-17. doi: 10.1002/pro.5560071007.
The three-dimensional structure of betaine aldehyde dehydrogenase, the most abundant aldehyde dehydrogenase (ALDH) of cod liver, has been determined at 2.1 A resolution by the X-ray crystallographic method of molecular replacement. This enzyme represents a novel structure of the highly multiple ALDH, with at least 12 distinct classes in humans. This betaine ALDH of class 9 is different from the two recently determined ALDH structures (classes 2 and 3). Like these, the betaine ALDH structure has three domains, one coenzyme binding domain, one catalytic domain, and one oligomerization domain. Crystals grown in the presence or absence of NAD+ have very similar structures and no significant conformational change occurs upon coenzyme binding. This is probably due to the tight interactions between domains within the subunit and between subunits in the tetramer. The oligomerization domains link the catalytic domains together into two 20-stranded pleated sheet structures. The overall structure is similar to that of the tetrameric bovine class 2 and dimeric rat class 3 ALDH, but the coenzyme binding with the nicotinamide in anti conformation, resembles that of class 2 rather than of class 3.
通过分子置换的X射线晶体学方法，已在2.1埃分辨率下确定了鳕鱼肝中最丰富的醛脱氢酶（ALDH）——甜菜碱醛脱氢酶的三维结构。这种酶代表了高度多样的ALDH的一种新结构，在人类中至少有12个不同的类别。这种第9类甜菜碱ALDH不同于最近确定的两种ALDH结构（第2类和第3类）。与它们一样，甜菜碱ALDH结构有三个结构域，一个辅酶结合结构域、一个催化结构域和一个寡聚化结构域。在有或没有NAD+存在的情况下生长的晶体具有非常相似的结构，并且辅酶结合时不会发生明显的构象变化。这可能是由于亚基内结构域之间以及四聚体中亚基之间的紧密相互作用。寡聚化结构域将催化结构域连接在一起形成两个20链的褶皱片层结构。整体结构类似于四聚体牛第2类和二聚体大鼠第3类ALDH，但辅酶与烟酰胺以反式构象结合，类似于第2类而不是第3类。
