Site-directed spin labeling

Site-directed spin labeling (SDSL) is a biophysical technique used to study the structure and dynamics of proteins and other biomolecules at the atomic level. It involves the introduction of a spin label—a stable free radical—at a specific site in a protein or biomolecule. This label can be introduced to a desired location within the protein using genetic engineering techniques, often by substituting a specific amino acid residue with a cysteine that can then be labeled with a spin label.