Electron transfer dissociation of native peptides facilitates enhanced identification of urinary peptides

Urine as a biofluid is commonly used in clinical diagnostics, including those performed during pregnancy. Urine is a rich source of polypeptides and polypeptidic protein degradation products, which have been filtered from blood plasma, thus urine has potential as a source for novel clinical diagnostics in disease. In this study, we examine the urinary peptidome from normal healthy women during pregnancy, and demonstrate ready observation of large polypeptide. We utilise the dissociation method, electron transfer dissociation (ETD) to increase the identification rate of the peptides present within these samples, as the polypeptide species observed in these samples are large and highly charged. An increase in the number of peptides whose identities could be ascribed using routine database searching methods was enabled via the use of ETD.