Issue 29, 2017

Quantifying reaction kinetics of the non-enzymatic decarboxylation of pyruvate and production of peroxymonocarbonate with hyperpolarized 13C-NMR

Abstract

The transient nature of intermediate states in chemical reactions has made their detailed investigation difficult. In this study, we demonstrate the utility of hyperpolarized 13C-NMR to directly observe and quantify the kinetics of the intermediate compound in the non-enzymatic decarboxylation of pyruvate via H2O2 with time resolutions of <1 s. Reactants were sequentially added to a reaction vessel within a 9.4 T NMR magnet while continuously acquiring spectra with a low flip angle, producing the first direct observation at room temperature of the previously proposed reaction intermediate, 2-hydroperoxy-2-hydroxypropanoate. We also performed a series of NMR experiments to determine the identity of a previously unidentified peak, which was found to be peroxymonocarbonate, the product of the side reaction between HCO3/CO2 and H2O2/OOH. Using the information obtained from these experiments, we developed a kinetic model which fully describes the mechanism of reaction and can be fit to experimental data to simultaneously determine multiple kinetic rate constants over several orders of magnitude. We also discuss the application of this reaction to the production of hyperpolarized bicarbonate for pH imaging experiments. This study presents a template for the use of hyperpolarized 13C-NMR to study the kinetics and reaction mechanisms of innumerable organic reactions which involve polarizable substrates.

Graphical abstract: Quantifying reaction kinetics of the non-enzymatic decarboxylation of pyruvate and production of peroxymonocarbonate with hyperpolarized 13C-NMR

Supplementary files

Article information

Article type
Paper
Submitted
30 Mar 2017
Accepted
06 Jul 2017
First published
13 Jul 2017

Phys. Chem. Chem. Phys., 2017,19, 19316-19325

Quantifying reaction kinetics of the non-enzymatic decarboxylation of pyruvate and production of peroxymonocarbonate with hyperpolarized 13C-NMR

N. Drachman, S. Kadlecek, I. Duncan and R. Rizi, Phys. Chem. Chem. Phys., 2017, 19, 19316 DOI: 10.1039/C7CP02041D

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