Abstract. Dynamic nuclear polarization (DNP)-enhanced magic angle spinning (MAS) nuclear magnetic resonance (NMR) of biological systems is a rapidly growing field. Large signal enhancements make the technique particularly attractive for
signal-limited cases, such as studies of complex biological assemblies or at
natural isotopic abundance. However, spectral resolution is considerably
reduced compared to ambient-temperature non-DNP spectra. Herein, we report a
systematic investigation into sensitivity and resolution of 1D and 2D
13C-detected DNP MAS NMR experiments on HIV-1 CA capsid protein tubular assemblies. We show that the magnitude and sign of signal enhancement as well as the homogeneous line width are strongly dependent on the biradical
concentration, the dominant polarization transfer pathway, and the
enhancement buildup time. Our findings provide guidance for optimal choice
of sample preparation and experimental conditions in DNP experiments.