Proton NMR of (15)N-choline metabolites enhanced by dynamic nuclear polarization.
Chemical shifts of protons can report on metabolic transformations such as the conversion of choline to phosphocholine. To follow such processes in vivo, magnetization can be enhanced by dynamic nuclear polarization (DNP). We have hyperpolarized in this manner nitrogen-15 spins in (15)N-labeled choline up to 3.3% by irradiating the 94 GHz electron spin resonance of admixed TEMPO nitroxide radicals in a magnetic field of 3.35 T during ca. 3 h at 1.2 K. The sample was subsequently transferred to a high-resolution magnet, and the enhanced polarization was converted from (15)N to methyl- and methylene protons, using the small (2,3)J((1)H,(15)N) couplings in choline. The room-temperature lifetime of nitrogen polarization in choline, T(1)((15)N) approximately 200 s, could be considerably increased by partial deuteration of the molecule. This procedure enables studies of choline metabolites in vitro and in vivo using DNP-enhanced proton NMR.
Sarkar
Riddhiman
R
Laboratory for Biomolecular Magnetic Resonance, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne, Switzerland.
Comment
Arnaud
A
Vasos
Paul R
PR
Jannin
Sami
S
Gruetter
Rolf
R
Bodenhausen
Geoffrey
G
Hall
Hélène
H
Kirik
Deniz
D
Denisov
Vladimir P
VP
D002794:Choline / Q000378:metabolism*; D007553:Isotope Labeling; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008280:Magnetics; D009587:Nitrogen Isotopes; D011522:Protons; D013113:Spin Labels
D009587:Nitrogen Isotopes; D011522:Protons; D013113:Spin Labels; D002794:Choline