FmRα analysis: Rapid and direct estimation of relaxation and kinetic parameters from dynamic nuclear polarization time courses. Issue 6 (2nd July 2014)

• Record Type: Journal Article
• Authors: Pagès, Guilhem; Kuchel, Philip W.
• Is Part Of: Magnetic resonance in medicine. Volume 73:Issue 6(2015:Jun.)
• Page Start: 2075
• Page End: 2080
• Publication Date: 2014-07-02
• Subjects: Nuclear magnetic resonance -- Periodicals; Electron paramagnetic resonance -- Periodicals; 616.07548
• DOI: 10.1002/mrm.25345
• Languages: English
• ISSNs: 0740-3194

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="mrm25345-sec-0001" sec-type="section"> <title>Purpose</title> <p>To introduce a direct method for estimating relaxation and kinetic parameter values from rapid dissolution dynamic nuclear polarization (RD‐DNP) NMR time courses.</p> </sec> <sec id="mrm25345-sec-0002" sec-type="section"> <title>Theory and Methods</title> <p>The analysis relied on a kinetic model that is often used to analyze data in these studies—a unidirectional (bio)chemical reaction with rate constant <italic>k</italic><sub>1</sub>, coupled to longitudinal relaxation of the magnetization of substrate and product that is characterized by the time constant <italic>T</italic><sub>1</sub>. The latter value was estimated from the width of the product curve (peak) at the height <italic>α</italic> relative to the maximum height. We showed <italic>α</italic> ∼ 0.8 under most conditions, so we measured the interval between the falling and rising parts of the curve at the relative height 0.8. We called this the "fall‐minus‐rise time at height <italic>α</italic>, " or <italic>FmR<sub>α</sub></italic>, and found that <italic>FmR</italic><sub>0.8</sub> ∼ <italic>T</italic><sub>1</sub>. The ratio <italic>β </italic>= (product signal/substrate signal) when the product is maximal was shown to be equal to <italic>k</italic><sub>1</sub><italic>T</italic><sub>1</sub>. Therefore, <italic>k</italic><sub>1</sub> = <italic>β/FmR</italic><sub>0.8</sub>.</p> </sec> <sec id="mrm25345-sec-0003" sec-type="section"> <title>Results</title> <p> <italic>FmR<sub>α</sub></italic> analysis was demonstrated with <sup>13</sup>C NMR RD‐DNP data recorded from hemolysates and from previously published data.</p> </sec> <sec id="mrm25345-sec-0004" sec-type="section"> <title>Conclusion</title> <p> <italic>FmR<sub>α</sub></italic> analysis enables immediate estimates of kinetic and relaxation parameters from <sup>13</sup>C NMR RD‐DNP data. The values can be used as initial estimates in more extensive computer‐based data‐regression analysis. Magn Reson Med 73:2075–2080, 2015. © 2014 Wiley Periodicals, Inc.</p> </sec> </abstract>