Digestion of a variety of synthetic peptides by proteasomes

Proteasomes are large multi-subunit enzymes that act as the main producers of antigenic peptides presented at the cell surface to CD8+ T cells. They can simply cut proteins or recombine their fragments thereby generating novel sequences, i.e. spliced peptides via a process called proteasome-catalysed peptide splicing (PCPS). In order to gain more insight into these processes, we here perform in vitro digestions of 55 synthetic polypeptide substrates by proteasome isoforms followed by LC-MS/MS measurements using different Mass Spectrometers.