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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Characterizing the dynamics of functionally relevant complexes of formate dehydrogenase
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Characterizing the dynamics of functionally relevant complexes of formate dehydrogenase

机译：表征甲酸脱氢酶功能相关复合物的动力学

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摘要

The potential for femtosecond to picosecond time-scale motions to influence the rate of the intrinsic chemical step in enzyme-catalyzed reactions is a source of significant controversy. Among the central challenges in resolving this controversy is the difficulty of experimentally characterizing thermally activated motions at this time scale in functionally relevant enzyme complexes. We re-port a series of measurements to address this problem using two-dimensional infrared spectroscopy to characterize the time scales of active-site motions in complexes of formate dehydrogenase with the transition-state-analog inhibitor azide (N_3~+). We observe that the frequency-frequency time correlation functions (FFCF) for the ternary complexes with NAD4 and NADH decay completely with slow time constants of 3.2 ps and 4.6 ps, respectively. This result suggests that in the vicinity of the transition state, the ac-tive-site enzyme structure samples a narrow and relatively rigid conformational distribution indicating that the transition-state structure is well organized for the reaction. In contrast, for the binary complex, we observe a significant static contribution to the FFCF similar to what is seen in other enzymes, indicating the presence of the slow motions that occur on time scales longer than our measurement window.
机译：飞秒级到皮秒级的时标运动可能影响酶催化反应中固有化学步骤的速率，这是引起广泛争议的根源。解决该争议的主要挑战之一是在功能相关的酶复合物中在此时间尺度上对热激活运动进行实验表征的困难。我们使用二维红外光谱法重新报告了一系列测量值，以解决该问题，以表征甲酸脱氢酶与过渡态类似物叠氮化物（N_3〜+）配合物中活性部位运动的时间尺度。我们观察到，具有NAD4和NADH的三元复合物的频率-频率时间相关函数（FFCF）分别以3.2 ps和4.6 ps的慢时间常数完全衰减。该结果表明，在过渡态附近，活性位点酶结构采样到狭窄且相对刚性的构象分布，表明过渡态结构对于反应而言是组织良好的。相反，对于二元复合物，我们观察到对FFCF的显着静态贡献，类似于在其他酶中观察到的，表明存在以比我们的测量窗口更长的时间标度出现的慢动作。

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  • 作者

    Jigar N. Bandaria; Samrat Dutta; Michael W. Nydegger; William Rock; Amnon Kohen; Christopher M. Cheatum;

  • 作者单位

    Department of Chemistry and Optical Science and Technology Center, University of Iowa, Iowa City, IA 52242;

    rnDepartment of Chemistry and Optical Science and Technology Center, University of Iowa, Iowa City, IA 52242;

    rnDepartment of Chemistry and Optical Science and Technology Center, University of Iowa, Iowa City, IA 52242;

    rnDepartment of Chemistry and Optical Science and Technology Center, University of Iowa, Iowa City, IA 52242;

    rnDepartment of Chemistry and Optical Science and Technology Center, University of Iowa, Iowa City, IA 52242;

    rnDepartment of Chemistry and Optical Science and Technology Center, University of Iowa, Iowa City, IA 52242;

  • 收录信息 美国《科学引文索引》(SCI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    2D IR spectroscopy; enzyme dynamics;

    机译：二维红外光谱酶动力学;

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