HeLa cells were treated with Nan-Dyne, a nanchangmycin probe bearing both alkyne and diazirine, irradiated with UV. For competition experiments, cells were also treated with an excess of nanchangmycin. Cells were irradiated with UV, lysed, clicked with azido-biotin, and proteins enriched on neutravidin beads. Samples were eluted on a SDS-Page gel and in-gel digested with trypsin.