Sven Van Bael, et. al, recently showcased the power of PEAKS for identification of modified peptides in the Journal of Proteome research.  Identification of modified peptides can be challenging because they are often found in low abundance relative to the unmodified version of the same peptide. Accurately localizing the modification to a specific site offers a further complication as there are often multiple positions where the modification can be found on the same peptide. Glutathionylation is a type of modification that has been difficult to identify. The study of glutathionylation is crucial as it has been linked to altered contractile functions of muscle filaments (myofilaments). Cardiomyocytes are a form of myofilament that is crucial for normal heart function. A new click chemistry workflow was used to enrich for glutathionylated peptides.

This was followed by an intelligent mass spectrometry approach where charge 2-3 peptides were fragmented with CID and charge 3-7 peptides were fragmented with ETD to ensure ideal fragmentation. With PEAKS Studio, 1763 glutathionylated peptides with specific Cys modification sites could be identified that were verified using Scaffold software. Clustering analyses showed that many of those glutathionylated proteins interact with genes relevant cardiomyopathy, a serious disease that can lead to heart failure.