Dr. Shining Loo of the XJTLU team Many bioactive proteins and peptides have multiple disulfide bonds between cysteine amino acids, which are crucial for maintaining their precise 3D folded structure.

Most sulfenic acids enjoy only a fleeting existence, quickly undergoing disulfide bond formation or further oxidation to sulfinic (–SO 2 H) or sulfonic (–SO 3 H) acids.

A Better Disulfide Reducing Agent Protein Biochemistry: Dithiobutylamine is a fast reducing agent for breaking cysteine-cysteine sulfur linkages by Jeffrey M. Perkel February 29, 2012 2 min read ...

These new bonds were only discovered in 2016, and are formed when the end of a lysine side-chain is linked to the end of a cysteine side-chain with an oxygen atom linking them together.