Dynamic nuclear polarization of nucleic acid with endogenously bound manganese
 

Dynamic nuclear polarization of nucleic acid with endogenously bound manganese

Abstract

We report the direct dynamic nuclear polarization (DNP) of 13C nuclei of a uniformly [13C,15N]-labeled, paramagnetic full-length hammerhead ribozyme (HHRz) complex with Mn2+ where the enhanced polarization is fully provided by the endogenously bound metal ion and no exogenous polarizing agent is added. A 13C enhancement factor of εÂ*=Â*8 was observed by intra-complex DNP at 9.4Â*T. In contrast, â??conventionalâ?? indirect and direct DNP experiments were performed using AMUPol as polarizing agent where we obtained a 1H enhancement factor of εÂ*â??Â*250. Comparison with the diamagnetic (Mg2+) HHRz complex shows that the presence of Mn2+ only marginally influences the (DNP-enhanced) NMR properties of the RNA. Furthermore two-dimensional correlation spectra (15Nâ??13C and 13Câ??13C) reveal structural inhomogeneity in the frozen, amorphous state indicating the coexistence of several conformational states. These demonstrations of intra-complex DNP using an endogenous metal ion as well as DNP-enhanced MAS NMR of RNA in general yield important information for the development of new methods in structural biology.



Source: Journal of Biomolecular NMR