Cysteine is a non essential amino acid. It contains sulfur in form of thiol group. A disulfide bond or bridge is formed between two thiol groups. It is represented as S-S. It is formed by oxidation of two cysteine molecules. The resultant disulfide bond is called as cystine which connects two polypeptide chains.
Cysteine is the only amino acid capable of forming disulfide bridge. It stabilizes protein's globular structure and plays an important role in protein folding and stability. Cysteine is required for protein synthesis, metabolic processes and detoxification. It is the part of beta-keratin which is the main protein in nails, hair and skin. If cysteine is mutated, formation of disulfide bond will be affected.
