The proton-translocating NADH-ubiquinone oxidoreductase (complex I ) is central to mitochondrial energy metabolism. In this study, we synthesized photoreactive acetogenin mimics (DLAs) and carried out photoaffinity labeling studies using bovine heart complex I. This project contains MALDI-TOF MS data of the 49-kDa subunit, which was specifically labeled by DLAs.