MTSSL is widely used in site-directed spin labeling (SDSL) for studying protein structure and dynamics through electron paramagnetic resonance (EPR) spectroscopy. It is particularly effective for attaching a spin label to cysteine residues in proteins, enabling researchers to investigate conformational changes, protein-protein interactions, and membrane protein dynamics. Its application extends to understanding the folding mechanisms of proteins and the effects of mutations on protein behavior. Additionally, MTSSL is utilized in distance measurements using pulsed EPR techniques, such as DEER (Double Electron-Electron Resonance), to map spatial arrangements within complex biomolecular systems. This makes it a valuable tool in structural biology and biophysics research.