(1-Oxyl-2,2,5,5-tetramethyl-∆3-pyrroline-3-methyl) Methanethiosulfonate

• CAT Number: R000352
• CAS Number: 81213-52-7
• Molecular Formula: C10H18NO3S2
• Molecular Weight: 264.378
• Purity: ≥95%
• Synonyms: 2,5-Dihydro-2,2,5,5-tetramethyl-3-[[(methylsulfonyl)thio]methyl]-1H-pyrrol-1-yloxy; MTSL; MTS; MTSSL; Otmpmms; Pmmts label; Otpm-mts.
• Storage: -20°C
• InChI: InChI=1S/C10H18NO3S2/c1-9(2)6-8(7-15-16(5,13)14)10(3,4)11(9)12/h6H,7H2,1-5H3
• InChIKey: BLSCGBLQCTWVPO-UHFFFAOYSA-N
• SMILES: CC1(C=C(C(N1[O])(C)C)CSS(=O)(=O)C)C

(1-Oxyl-2,2,5,5-tetramethyl-∆3-pyrroline-3-methyl) methanethiosulfonate (commonly abbreviated as MTSL) is a nitroxide spin label used in electron paramagnetic resonance (EPR) spectroscopy and structural biology. The compound is typically used to study protein dynamics, folding, and conformational changes. The methanethiosulfonate group in MTSL reacts specifically with sulfhydryl groups (–SH) on cysteine residues in proteins, forming a stable disulfide bond. The nitroxide moiety (N-O) acts as a paramagnetic probe, making it useful in EPR experiments to measure distances between labeled sites in proteins, providing insights into their structure and function in both solution and solid-state environments.