Comparative proteomics using iodoTMT to identify changes in protein expression and cysteine oxidation in Leishmania mexicana

Two cell-lines of Leishmania mexicana were investigated using a TMT-based approach; wild-type and an attenuated H-line. Half of each sample was fully reduced and all cysteine residues were labelled with the cysteine-reactive iodoTMT reagent, while the other half was reacted with N-ethylmaleimide to block all free cysteines before the remaining reversibly modified cysteines were reduced and labelled with iodoTMT. This allowed direct comparisons to be made between the level of modified cysteines and the total cysteine count.