Peptides and proteins in the vapor phase

This article provides a review of recent studies of the properties of unsol vated (and partially solvated) peptides and proteins. The methods used to p roduce vapor-phase peptide and protein ions are described along with some o f the techniques used to study them, such as H/D exchange, blackbody infrar ed radiative dissociation, and ion mobility measurements. Studies of unsolv ated peptides and proteins provide information about their intrinsic intram olecular interactions. The topics covered include the role of zwitterions a nd salt bridges in the vapor phase, Coulomb interactions in multiply charge d ions, the unfolding and refolding of vapor-phase proteins, and the stabil ity of unsolvated helices and sheets. Finally, dehydration and rehydration studies of proteins in the vapor phase are described. These can provide exq uisitely detailed information about hydration interactions, such as the ent halpy and entropy changes associated with adsorbing individual water molecu les.