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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Differential quantum tunneling contributions in nitroalkane oxidase catalyzed and the uncatalyzed proton transfer reaction
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Differential quantum tunneling contributions in nitroalkane oxidase catalyzed and the uncatalyzed proton transfer reaction

机译：硝基烷氧化酶催化和未催化质子转移反应中的差异量子隧穿贡献

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摘要

The proton transfer reaction between the substrate nitroethane and Asp-402 catalyzed by nitroalkane oxidase and the uncatalyzed process in water have been investigated using a path-integral free-energy perturbation method. Although the dominating effect in rate acceleration by the enzyme is the lowering of the quasi-classical free energy barrier, nuclear quantum effects also contribute to catalysis in nitroalkane oxidase. In particular, the overall nuclear quantum effects have greater contributions to lowering the classical barrier in the enzyme, and there is a larger difference in quantum effects between proton and deuteron transfer for the enzymatic reaction than that in water. Both experiment and computation show that primary KIEs are enhanced in the enzyme, and the computed Swain-Schaad exponent for the enzymatic reaction is exacerbated relative to that in the absence of the enzyme. In addition, the computed tunneling transmission coefficient is approximately three times greater for the enzyme reaction than the uncatalyzed reaction, and the origin of the difference may be attributed to a narrowing effect in the effective potentials for tunneling in the enzyme than that in aqueous solution.
机译：利用路径积分自由能摄动法研究了硝基链烷氧化酶催化的底物硝基乙烷与Asp-402之间的质子转移反应和水中的未催化过程。尽管该酶在速率加速中的主要作用是降低准经典自由能垒，但核量子效应也有助于硝基烷氧化酶的催化作用。特别是，总体的核量子效应对降低酶中的经典屏障具有更大的贡献，并且与水相比，用于酶促反应的质子和氘核转移之间的量子效应差异更大。实验和计算均表明，初级KIEs在酶中得到增强，相对于不存在酶时，酶促反应的计算出的Swain-Schaad指数加剧。另外，对于酶反应，计算的隧穿传输系数是未催化反应的约三倍，并且差异的起因可以归因于酶中隧穿的有效电势比水溶液中的有效电势的缩小效应。

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  • 作者

    Dan T. Major; Annie Heroux; Allen M. Orville; Michael P. Valley; Paul F. Fitzpatrick; Jiali Gao;

  • 作者单位

    Department of Chemistry, Supercomputing Institute and Digital Technology Center, University of Minnesota, Minneapolis, MN 55455 Department of Chemistry and the Lise Meitner-Minerva Center of Computational Quantum Chemistry, Bar-Man University, Ramat-Gan 52900, Israel;

    Department of Biology, Brookhaven National Laboratory, Upton, NY 11973;

    Department of Biology, Brookhaven National Laboratory, Upton, NY 11973;

    Department of Biochemistry, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229;

    Department of Biochemistry, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229;

    Department of Chemistry, Supercomputing Institute and Digital Technology Center, University of Minnesota, Minneapolis, MN 55455;

  • 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

    PI-FEP/UM simulations; enzyme catalysis; kinetic isotope effects; x-ray structure;

    机译：PI-FEP / UM仿真;酶催化;动力学同位素效应X射线结构;

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