Cysteine
An amino acid, one of the 20 building blocks of protein.
Cysteine can be synthesized by the body and is not essential to the diet.
Its key chemical feature is a thiol group that contains sulfur.
This thiol group can combine with the thiol group of another cysteine to form a disulfide bridge, which helps structural proteins and enzymes maintain their configuration.
Two cysteine molecules linked by a disulfide bridge make up the amino acid cystine.
The symbol for cysteine is Cys