Multi-step evolution of protein conformation on electrospray into the gas phase

In the gas phase, some properties of native versus denatured protein conformations correspond to those in solution, such as affinity for protons and physical cross section. However, the capacity for hydrogen/deuterium exchange is the opposite, with ubiquitin 7+ and 13+ ions exchanging > 60 D and ~15 D atoms, respectively. A variety of experimental methods now delineate a series of conformational perturbations that can occur in the 10−12 s to 10+2 s following electrospray, including side-chain collapse, hydrophobic and electrostatic non-covalent bond unfolding and refolding into a variety of non-native structures.