Compaction of RNA Hairpins and Their Kissing Complexes in Native Electrospray Mass Spectrometry

When electrosprayed from typical native MS solution conditions, RNA hairpins and kissing complexes acquire charge states at which they get significantly more compact in the gas phase than their initial structure in solution. Here, we also show the limits of using force field molecular dynamics to interpret the structures of nucleic acid complexes in the gas phase, as the predicted CCS distributions do not fully match the experimental ones. We suggest that higher level calculation levels should be used in the future.