Which functional group participates in disulphide bond formation in proteins?

A disulfide bond is a covalent bond between two sulfur atoms (-S-S-) formed by the coupling of two thiol (-SH) groups. Related Theory In the mammalian endoplasmic reticulum (ER), disulfide bond formation is achieved by the combined action of two types of enzyme: one capable offorming disulfides de novo and another able to introduce these disulfides into substrates.