Rigidity Analysis of Hydride Tunneling-Ready States From Secondary Kinetic Isotope Effects and Hammett Correlations: Relating to the Temperature Dependence of Kinetic Isotope Effects

IF 1.9 4区 化学 Q2 CHEMISTRY, ORGANIC
Mingxuan Bai, Grishma Singh, Yun Lu
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引用次数: 0

Abstract

Recent study on the effects of enzyme mutations on the primary kinetic isotope effects (1° KIEs) of H-tunneling reactions revealed that a more rigid system results in a weaker temperature dependence of KIEs, indicated by a smaller isotopic activation energy difference (∆Ea = EaD − EaH). In literature, a more rigid system has been defined by the presence of shorter, more densely populated hydrogen donor-acceptor distances (DADs) in both the productive reactant complexes (PRCs) and the tunneling-ready states (TRSs). Studying the relationship between DADPRC/DADTRS and ∆Ea can help validate existing H-tunneling models or guide the development of new theories. In a previous publication, we employed Hammett correlations on hydride acceptors (NAD+ analogues) to propose TRS electronic structures for qualitative analysis of DADTRS order. In this paper, we selected a pair of such systems and used secondary (2°) KIEs on the hydride donor (NADH analogue) to obtain quantitative DADTRS information at the molecular level. TRS structures were computed, and the corresponding 2° KIEs were calculated and fitted to the observed values to extract DADTRS data. PRC structures were also computed. The DADPRC/DADTRS information aligns with the rigidity order derived from Hammett correlation analysis, and the correlation between DADPRC/DADTRS and ∆Ea is consistent with observations in enzyme systems.

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来源期刊
CiteScore
3.60
自引率
11.10%
发文量
161
审稿时长
2.3 months
期刊介绍: The Journal of Physical Organic Chemistry is the foremost international journal devoted to the relationship between molecular structure and chemical reactivity in organic systems. It publishes Research Articles, Reviews and Mini Reviews based on research striving to understand the principles governing chemical structures in relation to activity and transformation with physical and mathematical rigor, using results derived from experimental and computational methods. Physical Organic Chemistry is a central and fundamental field with multiple applications in fields such as molecular recognition, supramolecular chemistry, catalysis, photochemistry, biological and material sciences, nanotechnology and surface science.
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