Protein Mass Effects on Formate Dehydrogenase.
Protein Mass Effects on Formate Dehydrogenase.
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DOI：
10.1021/jacs.7b08359
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发表时间：
2017-12-06
影响因子：
15
通讯作者：
Kohen A
中科院分区：
文献类型：
--
作者：
Ranasinghe C;Guo Q;Sapienza PJ;Lee AL;Quinn DM;Cheatum CM;Kohen A
同位素标记的酶(表示为“重的”或“天生的奥本海默”酶)已被用来测试蛋白质动力学在催化中的作用。最初的想法是，蛋白质的较高质量会降低其正常模式的频率，而不会改变其静电性。重酶被用来测试天然酶的振动是否与其催化的化学作用有关，不同的研究得出了模棱两可的结果。在这里，甲酸脱氢酶的本征动力学同位素效应的温度依赖性被用来研究H-供体到H-受体的距离作为蛋白质质量的函数的分布。根据天生的奥本海默式的键激活效应，重型酶中的蛋白质动力学被改变，以减少决定天然酶中过渡态采样的运动。这项工作的发现表明，与快频率有关的成分可以用Born-Oppenheimer酶假说(振动)解释，也可以用Born-Oppenheimer酶假说解释(静电)，这是基于对蛋白质质量依赖于供体-受体-距离和对催化的前向承诺的评估，以及稳态和单次周转测量。综上所述，这些发现表明，质量调制既影响了与催化化学相关的局部、快速的蛋白质振动，也影响了蛋白质在较慢时间尺度上的大分子静电学，即观察到了天生的奥本海默效应和非天生的奥本海默效应。通过与以往研究的比较得出结论，蛋白质的同位素标记可能对不同的系统有不同的影响，但使重酶研究成为一项非常令人兴奋的技术，以探索蛋白质中催化的动力学联系。
Isotopically labeled enzymes (denoted as “heavy” or “Born Oppenheimer” enzymes) have been used to test the role of protein dynamics in catalysis. The original idea was that the protein's higher mass would reduce the frequency of its normal-modes without altering its electrostatics. Heavy enzymes have been used to test if the vibrations in the native enzyme are coupled to the chemistry it catalyzes, and different studies have resulted in ambiguous findings. Here the temperature-dependence of intrinsic kinetic isotope effects of the enzyme formate dehydrogenase is used to examine the distribution of H-donor to H-acceptor distance as a function of the protein's mass. The protein dynamics are altered in the heavy enzyme to diminish motions that determine the transition state sampling in the native enzyme, in accordance with a Born Oppenheimer-like effect on bond activation. Findings of this work suggest components related to fast frequencies that can be explained by Born-Oppenheimer enzyme hypothesis (vibrational) and also slower timescale events that are non-Born-Oppenheimer in nature (electrostatic), based on evaluations of protein mass dependence of donor-acceptor-distance and forward commitment to catalysis along with steady state and single turnover measurements. Together, the findings suggest that the mass modulation affected both local, fast, protein vibrations associated with the catalyzed chemistry, and the protein's macromolecular electrostatics at slower timescales, i.e., both Born Oppenheimer and non-Born Oppenheimer effects are observed. Comparison to previous studies leads to the conclusion that isotopic labeling of the protein may have different effects on different systems, however making heavy enzyme studies a very exciting technique for exploring the dynamics link to catalysis in proteins.
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影响因子：
2.9
作者：
Francis K;Sapienza PJ;Lee AL;Kohen A
通讯作者：
Kohen A
影响因子：
15
作者：
Bandaria JN;Cheatum CM;Kohen A
通讯作者：
Kohen A
影响因子：
15
作者：
Ruiz-Pernia JJ;Luk LY;García-Meseguer R;Martí S;Loveridge EJ;Tuñón I;Moliner V;Allemann RK
通讯作者：
Allemann RK
影响因子：
3.3
作者：
Antoniou, Dimitri;Schwartz, Steven D.
通讯作者：
Schwartz, Steven D.
影响因子：
4.8
作者：
Horowitz, Scott;Yesselman, Joseph D.;Trievel, Raymond C.
通讯作者：
Trievel, Raymond C.