6533b82dfe1ef96bd1290faa

RESEARCH PRODUCT

iPRG 2012 Study: Detecting Modified Peptides in a Complex Mixture

subject

description

Nature uses a wide variety of protein post-translational modifications to regulate protein structure and activity and tandem mass spectrometry has emerged as the most powerful analytical approach to detect these moieties. However, modified peptides present special challenges for characterization. First, they are generally present at sub-stoichiometric levels, meaning that without enrichment strategies samples are dominated by unmodified peptides, so finding the modified peptides may be a challenge. Secondly, the modifications may have unique fragmentation behaviors in collision-induced dissociation (CID), which may need to be considered by database search engines. Finally, if there are multiple residues within a given peptide that could bear a particular modification type, then it is necessary to identify fragment ions that frame either side of the modification site in order to be able to localize the exact site of modification within the peptide.