How enzymes break carbon-fluorine bonds

脱卤酶破坏碳-卤键。最引人注目的是酶能够打破有机化学中最稳定的键，碳氟键。由NSERC战略拨款支持，并与E。Edwards（U of T）和A.Yakunin（SGC），我们筛选了脱卤酶的微生物基因组。我们将确认的脱卤酶的数量从2个提高到20个，其中9个脱氟酶和4个代表L-2-卤酸脱卤酶蛋白家族的第一个脱氟酶成员。我们将确定形成其催化能力基础的分子相互作用，为大多数难降解环境污染物的生物降解解决方案做出贡献。我们已经使用ITC来确定天然和突变酶的动力学参数。氟乙酸脱卤酶RPA 1163来自R. palustris进行了详细的表征。其静态高分辨率晶体结构（~ 1.2 μ m;天然和突变体）与各种配体提供了一组催化中间体的“快照”。他们还指出，瞬时结合位点的基板接近催化机械和旋转运动后转化。我们的静态分析表明，晶体适应完整的催化循环，而不影响衍射能力。我们合成了底物的“笼状”1-（2-硝基苯基）乙基衍生物。短的紫外激光脉冲可以将这种“笼状化合物”转化为底物，引发其结合和催化转化。应用时间分辨（TR）-劳厄技术，我们将收集衍射数据作为时间的函数，因为启动和转换成一个“电影”的催化反应，允许观察几乎原子的细节。我们与世界上最重要的激光触发TR劳厄衍射专家合作，以加快我们的进展，并确保及时获得他们的一流资源。我们的系统也将作为开发TR晶体学单色方法的测试案例。此外，我们计划通过将光触发LUV结构域与脱氟酶融合来设计光敏脱卤酶，这将使我们能够预制底物复合物，从而将反应从双分子转移到单分子，从而更容易解释数据。

Dehalogenase enzymes break carbon-halogen bonds. Most remarkable are enzymes able to break the most stable bond in organic chemistry, the carbon-fluorine bond. Supported by an NSERC Strategic Grant and in collaboration with E. Edwards (U of T) and A.Yakunin (SGC), we screened microbial genomes for dehalogenases. We raised the number of confirmed dehalogenases from 2 to 20, 9 of them defluorinases and 4 representing the first defluorinase members of the L-2-haloacid dehalogenase protein family. We will determine the molecular interactions that form the basis of their catalytic power, contributing to biodegradation solutions for most recalcitrant environmental pollutants. We have used ITC to determine kinetic parameters of native and mutant enzymes. The fluoroacetate dehalogenase RPA1163 from R. palustris was characterized in detail. Its static high-resolution crystal structures (~ 1.2 Å; native and mutants) with various ligands provided a set of 'snapshots' of the catalytic intermediates. They also indicated transient binding sites as the substrate approaches the catalytic machinery and rotational movements upon transformation. Our static analyses showed that the crystals accommodate the complete catalytic cycle without compromising diffraction power. We have synthesized the "caged" 1-(2-nitrophenyl) ethyl-derivative of the substrate. Short UV-laser pulses can transform this "caged compound" into the substrate, initiating its binding and catalytic conversion. Applying time- resolved (TR)-Laue techniques, we will collect diffraction data as a function of time since initiation and convert them to a "movie" of the catalytic reaction, allowing observation in almost atomic detail. We collaborate with the world's foremost experts in laser-triggered TR-Laue-diffraction to accelerate our progress and secure timely access to their superb resources. Our system will also serve as a test case for developing monochromatic methods for TR crystallography. In addition, we plan to engineer a light-sensitive dehalogenase by fusing a light-trigger LUV domain to the defluorinase, which will allow us to preform the substrate complex, thereby shifting the reaction from a bimolecular to a unimolecular one, allowing for easier data interpretation.