abstract
Dynamic Nuclear Polarization (DNP) can substantially enhance the sensitivity of NMR experiments. Among the implementations of DNP, ex-situ dissolution DNP (dDNP) achieves high signal enhancement levels owing to a combination of a large temperature factor between 1.4 and 300 K with the actual DNP effect in the solid state at 1.4 K. For sufficiently long T-1 relaxation times much of the polarization can be preserved during dissolution with hot solvent, thus enabling fast experiments during the life time of the polarization. Unfortunately, for many metabolites found in biological samples such as blood, relaxation times are too short to achieve a significant enhancement. We have therefore introduced C-13-carbonyl labeled acetyl groups as probes into amino acid metabolites using a simple reaction protocol. The advantage of such tags is a sufficiently long T-1 relaxation time, the possibility to enhance signal intensity by introducing C-13, and the possibility to identify tagged metabolites in NMR spectra. We demonstrate feasibility for mixtures of amino acids and for blood serum. In two-dimensional dDNP-enhanced HMQC experiments of these samples acquired in 8 s we can identify acetylated amino acids and other metabolites based on small differences in chemical shifts. (C) 2019 Published by Elsevier Inc.
keywords
NMR; POLARIZATION; METABOLISM; BINDING
subject category
Biochemistry & Molecular Biology; Physics; Spectroscopy
authors
Katsikis, S; Marin-Montesinos, I; Ludwig, C; Gunther, UL
our authors
Ildefonso Marin Montesinos
Junior Researcheracknowledgements
Research leading to these results received funding from the European Commission in the context of the METAFLUX FP7 ITN project (264780). The authors would like to thank Oxford Instruments for hosting SK as a researcher as part of this grant and HWB-NMR for providing the support needed for the completion of this work. We are also grateful to the Wellcome Trust for supporting access to NMR instruments at the Henry Wellcome Building for Biomolecular NMR in Birmingham (grant number 208400/Z/17/Z).