Institute of Chemical Biology and Drug Discovery, Department of Chemistry, Stony Brook University , Stony Brook, New York 11794-3400, United States.
Rudolf Virchow Center for Experimental Biomedicine, Institute for Structural Biology, University of Würzburg , 97080 Würzburg, Germany.
J Am Chem Soc. 2017 Mar 8;139(9):3417-3429. doi: 10.1021/jacs.6b11148. Epub 2017 Feb 22.
A critical goal of lead compound selection and optimization is to maximize target engagement while minimizing off-target binding. Since target engagement is a function of both the thermodynamics and kinetics of drug-target interactions, it follows that the structures of both the ground states and transition states on the binding reaction coordinate are needed to rationally modulate the lifetime of the drug-target complex. Previously, we predicted the structure of the rate-limiting transition state that controlled the time-dependent inhibition of the enoyl-ACP reductase InhA. This led to the discovery of a triazole-containing diphenyl ether with an increased residence time on InhA due to transition-state destabilization rather than ground-state stabilization. In the present work, we evaluate the inhibition of InhA by 14 triazole-based diphenyl ethers and use a combination of enzyme kinetics and X-ray crystallography to generate a structure-kinetic relationship for time-dependent binding. We show that the triazole motif slows the rate of formation for the final drug-target complex by up to 3 orders of magnitude. In addition, we identify a novel inhibitor with a residence time on InhA of 220 min, which is 3.5-fold longer than that of the INH-NAD adduct formed by the tuberculosis drug, isoniazid. This study provides a clear example in which the lifetime of the drug-target complex is controlled by interactions in the transition state for inhibitor binding rather than the ground state of the enzyme-inhibitor complex, and demonstrates the important role that on-rates can play in drug-target residence time.
先导化合物的选择和优化的一个关键目标是在最大程度地提高靶标占有率的同时,最小化脱靶结合。由于靶标占有率是药物-靶标相互作用的热力学和动力学的函数,因此需要合理调节药物-靶标复合物的寿命,就需要知道结合反应坐标上的基态和过渡态的结构。此前,我们预测了控制烯酰基辅酶 A 还原酶 InhA 时变抑制的限速过渡态的结构。这导致发现了一种含有三唑的二苯醚,由于过渡态的去稳定化而不是基态的稳定化,它在 InhA 上的停留时间增加。在本工作中,我们评估了 14 种基于三唑的二苯醚对 InhA 的抑制作用,并结合酶动力学和 X 射线晶体学来生成时变结合的结构-动力学关系。我们表明,三唑基序使最终药物-靶标复合物的形成速率最多减慢了 3 个数量级。此外,我们确定了一种新型抑制剂,其在 InhA 上的停留时间为 220 min,比结核药物异烟肼形成的 INH-NAD 加合物长 3.5 倍。该研究提供了一个明确的例子,即药物-靶标复合物的寿命是由抑制剂结合的过渡态相互作用而不是酶-抑制剂复合物的基态控制的,并证明了结合速率在药物-靶标停留时间中的重要作用。