Dynamic Nuclear Polarization/Solid-State NMR Spectroscopy of Membrane Polypeptides: Free-Radical Optimization for Matrix-Free Lipid Bilayer Samples.

摘要: Dynamic nuclear polarization (DNP) boosts the sensitivity of NMR spectroscopy by orders magnitude and makes investigations previously out scope possible. For magic-angle-spinning (MAS) solid-state studies, samples are typically mixed with biradicals dissolved in a glass-forming solvent investigated at cryotemperatures. Herein, we present new biradical polarizing agents developed for matrix-free such as supported lipid bilayers, which systems widely used investigation membrane polypeptides high biomedical importance. A series 11 different structures, geometries, physicochemical properties were comprehensively tested DNP performance some them specifically membranes. The membrane-anchored PyPol-C16, AMUPOL-cholesterol, bTurea-C16 found to exhibit improved g-tensor alignment, inter-radical distance, dispersion. Consequently, these show highest signal enhancement factors so far obtained membranes or other may potentially shorten acquisition times three magnitude. Furthermore, optimal biradical-to-lipid ratio, sample deuteration, composition determined under static MAS conditions. To rationalize better, was measured using 13 C 15 N signals lipids peptide function concentration, build-up time, resonance line width, quenching effect, microwave power, frequency.