Updated project metadata. Oligopeptidases Prep and OOP are enzymes located in mitochondria and chloroplasts responsible for the cleavage of long peptides (8 to 65 aas) down to short peptides (3 to 7 aas), which in turn are degraded to free amino acids by aminopeptidases such as M1 and M17. In this study, Arabidopsis thaliana knockout mutants of the genes for these enzymes were studied by proteomics using a TMT (tandem mass tags) isobaric tags quantification strategy combined with HiRIEF LC-MS on a Q-Exactive Mass Spectrometer.