Imaging NMR for the quantitative study of protein-ligand interactions and enzymatic reactions in a single NMR tube Serena Monaco 1 Jesus Angulo 2 , Matthew Wallace 1 1 University of East Anglia, UK, 2 Instituto de Investigaciones Químicas (IIQ), Spain NMR is a powerful tool to study protein-ligand complexes as it unveils atomic details of the interactions (and enzymatic reactions) in solution, while also allowing fully quantitative approaches, such as determination of binding dissociations, K D ‘sby titration of a protein with increasing concentrations of ligand. 1 Imaging NMR is a new technique enabling us to condense any titrations in a single NMR tube containing a gradient of the analyte of interest, extracting accurate parameters in a small fraction of the experimental time and material required for the manual approach. 2 Imaging NMR has the huge potential of accelerating drug discovery and fundamental research. We aimed at the development of: 1) K D and binding specificity, through the newly implemented Imaging Saturation Transfer Difference (STD) NMR experiment; and 2) the determination of enzymatic parameters K M and V Max from fitting the Michalis Menten equation. Both implementations are performed in a single NMR tube, with a huge reduction of time and resources compared to conventional methodologies. We prepare samples containing a controlled gradient of ligand against homogeneous concentration of protein, and developed for the first time Imaging STD NMR to obtain the K D of the complexes in a single tube. For 2) we prepared substrate gradients against homogeneous enzymes to extract K M and V Max . We prove that 1) Imaging STD NMR is an effective methodology to extract dissociation constant, obtaining values in good agreement with literature in 10%-20% of the experimental time relative to the manual STD NMR titration. Using the same approach, we can also assess the specificity of binding, following the evolution of the binding epitope upon increasing ligand excess. 3 We also demonstrated that 2) by Imaging NMR we can condense enzymatic assays in a single NMR tube. Whereas UV spectroscopy is the established technique for this, its main limitation is the need of a chromogen, often precluding direct detection and/or excluding physiological substrates. By Imaging NMR we manage to obtain accurate K M and V Max in a single sample and with no limitation on the nature of substrate. 4 References 1. J. Angulo, et al. Chemistry–A European Journal 16.26 (2010): 7803-7812. 2. M. Wallace, et al. Analytical chemistry 90.6 (2018): 4160-4166.
3. S. Monaco et al. Submitted. 4. S. Monaco et al. Unpublished.
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