Fast protein motions are coupled to enzyme H-transfer reactions

Christopher Pudney, Andrew Guerriero, Nicola Jane Baxter, Linus O Johannissen, Jonathan Peter Waltho, Sam Hay, Nigel S Scrutton

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Abstract

Coupling of fast protein dynamics to enzyme chemistry is controversial and has ignited considerable debate, especially over the last 15 years in relation to enzyme-catalysed H-transfer. H-transfer can occur by quantum tunneling and the tempera-ture-dependence of kinetic isotope effects (KIEs) has emerged as the ‘gold standard’ descriptor of these reactions. The anomalous temperature dependence of KIEs is often rationalised by invoking fast motions to facilitate H-transfer, yet crucially, direct evidence for coupled motions is lacking. Here, we have perturbed vibrational motions in pentaerythritol tetranitrate reductase (PETNR) by isotopic substitution where all non-exchangeable atoms were replaced with the corresponding heavy isotope (13C, 15N and 2H). The KIE temperature dependence is perturbed by heavy isotope labelling, demonstrating a direct link between (promoting) vibrations in the protein and the observed KIE. We show causality between fast motions and enzyme chemistry and demonstrate how this impacts on experimental KIEs for enzyme reactions
Original languageEnglish
Pages (from-to)2512-2517
Number of pages3
JournalJournal of the American Chemical Society
Volume135
Issue number7
Early online date1 Feb 2013
DOIs
Publication statusPublished - Feb 2013

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    Pudney, C., Guerriero, A., Baxter, N. J., Johannissen, L. O., Waltho, J. P., Hay, S., & Scrutton, N. S. (2013). Fast protein motions are coupled to enzyme H-transfer reactions. Journal of the American Chemical Society, 135(7), 2512-2517. https://doi.org/10.1021/ja311277k