... contains mainly13C8, whereas the squaresrepresent the distribution 1 Da higher. To determine the mass increase with increasing time of deamidation(pH 9.6), the best fit of calculated intensity ... sites, such as the protonated side chains of basic residues, in solution are solvated out into the aqueous phase, while in the gas phase they are insteadsolvated onto the protein backbone, with ... expression are compared accurately by iso-topically labeling the proteins from one and compar-ing in their mixture the corresponding peaks of theirrespective peptides, usually differing by three...