page_title: Disulfide
section_title: Occurrence in biology
hierarchical_section_title: Disulfide / Occurrence in biology
context_page_description: In chemistry, a disulfide refers to a functional group with the structure R−S−S−R′. The linkage is also called an SS-bond or sometimes a disulfide bridge and is usually derived by the coupling of two thiol groups. In biology, disulfide bridges formed between thiol groups in two cysteine residues are an important component of the secondary and tertiary structure of proteins. The connection is a persulfide, in analogy to its congener, peroxide, but this terminology is rarely used, except in reference to hydrodisulfides.
  In inorganic chemistry disulfide usually refers to the corresponding anion S²⁻
  ₂.
caption: Schematic of disulfide bonds crosslinking regions of a protein