Bound Cations Significantly Stabilize the Structure of Multiprotein Complexes in the Gas Phase

Positively a gas: Protein structure determination using mass spectrometry can be assisted by the addition of stabilizing cations to the gas-phase molecule. Densely charged cations (see scheme, green) are found to stabilize protein tertiary structure for accurate mass determination of homo- or heterogeneous protein complexes. The cations remain tightly bound to the protein throughout the analysis, allowing the protein to remain in a folded state.