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Oscillatory Active-site Motions Correlate with Kinetic Isotope Effects in Formate Dehydrogenase
Journal article   Peer reviewed

Oscillatory Active-site Motions Correlate with Kinetic Isotope Effects in Formate Dehydrogenase

Philip Pagano, Qi Guo, Chethya Ranasinghe, Evan Schroeder, Kevin Robben, Florian Häse, Hepeng Ye, Kyle Wickersham, Alán Aspuru-Guzik, Dan T Major, …
ACS catalysis, Vol.9(12), pp.11199-11206
12/06/2019
DOI: 10.1021/acscatal.9b03345
PMCID: PMC8118594
PMID: 33996196
url
https://www.osti.gov/biblio/1801438View
Open Access

Abstract

Thermal motions of enzymes have been invoked to explain the temperature dependence of kinetic isotope effects (KIE) in enzyme-catalyzed hydride transfers. Formate dehydrogenase (FDH) from Candida boidinii exhibits a temperature independent KIE that becomes temperature dependent upon mutation of hydrophobic residues in the active site. Ternary complexes of FDH that mimic the transition state structure allow investigation of how these mutations influence active-site dynamics. A combination of X-ray crystallography, two-dimensional infrared (2D IR) spectroscopy, and molecular dynamic simulations characterize the structure and dynamics of the active site. FDH exhibits oscillatory frequency fluctuations on the picosecond timescale, and the amplitude of these fluctuations correlates with the temperature dependence of the KIE. Both the kinetic and dynamic phenomena can be reproduced computationally. These results provide experimental evidence for a connection between the temperature dependence of KIEs and motions of the active site in an enzyme-catalyzed reaction consistent with activated tunneling models of the hydride transfer reaction.
Enzyme Catalysis dynamics formate dehydrogenase KIE oscillation Protein dynamics two-dimensional infrared spectroscopy

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