42006-86-0Relevant academic research and scientific papers
A critical test of the tunneling and coupled motion concept in enzymatic alcohol oxidation
Roston, Daniel,Kohen, Amnon
, p. 13624 - 13627 (2013)
The physical mechanism of C-H bond activation by enzymes is the subject of intense study, and we have tested the predictions of two competing models for C-H activation in the context of alcohol dehydrogenase. The kinetic isotope effects (KIEs) in this enzyme have previously suggested a model of quantum mechanical tunneling and coupled motion of primary (1) and secondary (2) hydrogens. Here we measure the 2 H/T KIEs with both H and D at the 1 position and find that the 2 KIE is significantly deflated with D-transfer, consistent with the predictions of recent Marcus-like models of H-transfer. The results suggest that the fast dynamics of H-tunneling result in a 1 isotope effect on the structure of the tunneling ready state: the trajectory of D-transfer goes through a shorter donor-acceptor distance than that of H-transfer.
