Structure of a Biosynthetic Enzyme for Unsaturated Fatty Acids

β-羟基癸酰酶的三维结构 来自E.大肠杆菌将通过X射线测定 结晶学 这种酶是生物合成 E.大肠杆菌， 脱水和双键异构化反应。 的 已知酶具有通过巯基抑制自杀的性质 3-癸炔酸的酯。 这种特定的，不可逆转的， 将利用酶的共价修饰， 为晶体结构提供重原子标记 保持战略定力 晶体结构将通过使用 反常色散由于重原子纳入 抑制剂化合物。 非常强烈的衍射晶体的 本发明的酶表明，结构测定可以 达到非常高的分辨率。 因此，晶体学 将进行超低温研究， 尽可能地定义结构细节。 的 结构测定的结果有望解释 该酶对底物酰基的高度特异性， 验证单个活性位点负责催化 两个酶反应，指出可能的 与其他结合疏水分子的蛋白质相似， 并提供蛋白质中原子迁移率的额外数据 分子。

The three-dimensional structure of the enzyme B-hydroxydecanoyl thioester dehydrase from E. coli will be determined by X-ray crystallography. This enzyme is essential for biosynthesis of unsaturated fatty acids in E. coli by catalyzing both dehydration and double-bond isomerization reactions. The enzyme is known for its property of suicide inhibition by thiol esters of 3-decynoic acid. This specific, irreversible, covalent modification of the enzyme will be exploited to provide heavy-atom labels for the crystallographic structure determination. The crystal structure will be solved by use of anomalous dispersion due to heavy-atoms incorporated in the inhibitor compounds. Very strongly diffracting crystals of the subject enzyme indicate that the structure determination can proceed to very high resolution. Accordingly, crystallographic studies at ultra-low temperature will be pursued in order to define structural details to the fullest extent possible. The results of the structure determination are expected to explain the enzyme's high degree of specificity for substrate acyl, to verify that a single active site is responsible for catalysis of the two enzymatic reactions, to point out possible similarities to other proteins that bind hydrophobic molecules, and to provide additional data on atomic mobility in protein molecules.