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Dissolution Dynamic Nuclear Polarization Instrumentation for Real-time Enzymatic Reaction Rate Measurements by NMR
Published on: February 23, 2016
Liquid state DNP of water at 9.2 T: an experimental access to saturation
Petr Neugebauer1, Jan G Krummenacker, Vasyl P Denysenkov
1Institute of Physical and Theoretical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe-University, Max-von-Laue-Str. 7, 60438, Frankfurt am Main, Germany.
Abstract:
We have performed liquid state ("Overhauser") Dynamic Nuclear Polarization (DNP) experiments at high magnetic field (9.2 T, corresponding to 260 GHz EPR and 400 MHz (1)H-NMR resonance frequency) on aqueous solutions of (14)N-TEMPOL nitroxide radicals. Integrated signal enhancements exceeding -80 were observed for the water protons at microwave superheated temperatures (160 °C) and still -14 at ambient temperatures (45 °C) relevant to biological applications. Different contributions contributing to the DNP enhancement such as saturation factor, leakage factor and sample temperature under microwave irradiation could be determined independently for a high spin concentration of 1 M, allowing the calculation of the coupling factors as a function of temperature and a quantitative comparison of this parameter with values derived from field dependent relaxation measurements or predictions from MD simulation.
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