Examination of enzymatic H-tunneling through kinetics and dynamics.
Examination of enzymatic H-tunneling through kinetics and dynamics.
复制标题
DOI：
10.1021/ja902120t
复制
发表时间：
2009-07-29
影响因子：
15
通讯作者：
Kohen A
中科院分区：
文献类型：
--
作者：
Bandaria JN;Cheatum CM;Kohen A
近年来，酶催化反应的同位素效应及其温度依赖性的动力学测量导致了理论模型的发展，用于合理化的结果。这些模型表明，在飞秒到皮秒（fs到ps）的时间尺度上的运动调节了催化反应的环境。由于直接影响共价键裂解的运动的快速性质，将与该步骤相关的酶动力学和动力学关联起来是具有挑战性的。我们报告了甲酸脱氢酶（FDH）的研究，该研究将内在动力学同位素效应（KIE）的温度依赖性与fs-ps时间尺度下的环境动力学测量进行了比较（Bandaria等人，J. Am. 2008，130，22-23）。实验动力学和动力学的比较结果与环境耦合H-隧道模型（也称为Marcus模型）的模型一致。显然，在隧穿准备构象，供体-受体距离，取向和波动，似乎是很好地调整H-转移，不受热波动慢于20 ps。这种现象在过去被认为在酶促反应中是相当普遍的。在这里，一个单一的化学步骤和fs-ps时间尺度上的动力学和动力学测量，分别提供了新的见解和支持相关的理论模型。此外，该方法可应用于其他系统，并可用于检测供体和受体的组织不理想的突变体，或具有不同刚性和不同最适温度的酶。
In recent years, kinetic measurements of isotope effects of enzyme catalyzed reactions and their temperature dependence led to the development of theoretical models that were used to rationalize the findings. These models suggested that motions at the femto- to pico-second (fs to ps) time scale modulate the environment of the catalyzed reaction. Due to the fast nature of motions that directly affect the cleavage of a covalent bond, it is challenging to correlate the enzyme kinetics and dynamics related to that step. We report a study of formate dehydrogenase (FDH) that compares the temperature dependence of intrinsic kinetic isotope effects (KIEs) to measurements of the environmental dynamics at the fs-ps time scale (Bandaria et al., J. Am. Chem. Soc. 2008, 130, 22–23). The findings from this comparison of experimental kinetics and dynamics are consistent with models of environmentally coupled H-tunneling models, also known as Marcus-like models. Apparently, at tunneling ready conformations, the donor-acceptor distance, orientation, and fluctuations, seems to be well tuned for H- transfer and are not affected by thermal fluctuations slower than 20 ps. This phenomenon has been suggested in the past to be quite general in enzymatic reactions. Here, the kinetics and the dynamics measurements on a single chemical step and on fs-ps time scale, respectively, provide new insight and support for the relevant theoretical models. Furthermore, this methodology could be applied to other systems and be used to examine mutants for which the organization of the donor and acceptor is not ideal, or enzymes with different rigidity and different temperature optimum.
登录
查看更多内容
影响因子：
3.3
作者：
Agarwal, R;Krueger, BP;Fleming, GR
通讯作者：
Fleming, GR
影响因子：
3.9
作者：
Johannissen, Linus O.;Scrutton, Nigel S.;Sutcliffe, Michael J.
通讯作者：
Sutcliffe, Michael J.
影响因子：
5.6
作者：
LAMZIN, VS;DAUTER, Z;WILSON, KS
通讯作者：
WILSON, KS
影响因子：
15
作者：
Hatcher, E;Soudackov, AV;Hammes-Schiffer, S
通讯作者：
Hammes-Schiffer, S
DOI：
10.1073/pnas.95.26.15315
发表时间：
1998-12-22
影响因子：
11.1
作者：
Lim, MH;Hamm, P;Hochstrasser, RM
通讯作者：
Hochstrasser, RM