MTSL (S-(1-oxyl-2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrol-3-yl)methyl methanesulfonothioate) is a chemical compound which can be used as a nitroxide (amine oxide) paramagnetic spin label in protein Electron paramagnetic resonance and nuclear magnetic resonance spectroscopy experiments. MTSL is attached via a disulfide bond to a cysteine residue, e...