Boehr David D, McElheny Dan, Dyson H Jane, Wright Peter E
Department of Molecular Biology and Skaggs Institute for Chemical Biology, Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
Science. 2006 Sep 15;313(5793):1638-42. doi: 10.1126/science.1130258.
We used nuclear magnetic resonance relaxation dispersion to characterize higher energy conformational substates of Escherichia coli dihydrofolate reductase. Each intermediate in the catalytic cycle samples low-lying excited states whose conformations resemble the ground-state structures of preceding and following intermediates. Substrate and cofactor exchange occurs through these excited substates. The maximum hydride transfer and steady-state turnover rates are governed by the dynamics of transitions between ground and excited states of the intermediates. Thus, the modulation of the energy landscape by the bound ligands funnels the enzyme through its reaction cycle along a preferred kinetic path.
我们利用核磁共振弛豫色散来表征大肠杆菌二氢叶酸还原酶的高能构象亚态。催化循环中的每个中间体都采样低能激发态，其构象类似于前后中间体的基态结构。底物和辅因子通过这些激发亚态进行交换。最大氢化物转移和稳态周转速率由中间体基态和激发态之间的转变动力学控制。因此，结合配体对能量景观的调节使酶沿着优选的动力学路径通过其反应循环。
