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Author Spotlight: Exploring Intrinsically Disordered Protein Dynamics Through NMR Relaxation Experiments
Published on: November 1, 2024
Determination of partition coefficients using 1 H NMR spectroscopy and time domain complete reduction to
David Soulsby1, Jeryl A M Chica1
1Chemistry Department, University of Redlands, 1200 E. Colton Avenue, Redlands, CA, 92374-3755, USA.
Abstract:
We have developed a simple, direct and novel method for the determination of partition coefficients and partitioning behavior using 1 H NMR spectroscopy combined with time domain complete reduction to amplitude-frequency tables (CRAFT). After partitioning into water and 1-octanol using standard methods, aliquots from each layer are directly analyzed using either proton or selective excitation NMR experiments. Signal amplitudes for each compound from each layer are then extracted directly from the time domain data in an automated fashion and analyzed using the CRAFT software. From these amplitudes, log P and log D7.4 values can be calculated directly. Phase, baseline and internal standard issues, which can be problematic when Fourier transformed data are used, are unimportant when using time domain data. Furthermore, analytes can contain impurities because only a single resonance is examined and need not be UV active. Using this approach, we examined a variety of pharmaceutically relevant compounds and determined partition coefficients that are in excellent agreement with literature values. To demonstrate the utility of this approach, we also examined salicylic acid in more detail demonstrating an aggregation effect as a function of sample loading and partition coefficient behavior as a function of pH value. This method provides a valuable addition to the medicinal chemist toolbox for determining these important constants. Copyright © 2017 John Wiley & Sons, Ltd.
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