2-Mercaptoethanol (${\mathrm{HOCH}}_2{\mathrm{CH}}_2\mathrm{SH}$)

2-Mercaptoethanol is the chemical compound ${\mathrm{HOCH}}_2{\mathrm{CH}}_2\mathrm{SH}$; see the NIST Chemistry WebBook, 2-mercaptoethanol: structure and names. In the ribonuclease A refolding experiment, it breaks protein disulfide bonds, while the peptide bonds of the protein backbone remain intact. This separates a change in crosslinks from cutting the polypeptide chain.