Cysteine and Cystine will be grouped together due to their striking similarities, molecules of cystine are made up of two molecules of cysteine joined together. The amino acid Cysteine is very unstable and easily converts to L-cystine which is also capable of converting back into cysteine when required. Both are very important sulfur containing amino acids that aid in skin formation and detoxification. Alpha-keratin, the chief protein in the fingernails, skin, hair, and toenails; consists of some cysteine. Which aids in collagen production and maintains the proper elasticity/texture of the skin. Cysteine may also be found in the digestive enzymes.
One of the best free radical destroyers cysteine works best as a detoxifier when taken with selenium and vitamin E. Cysteine has been found to also be a precursor to gultathione (a substance that bonds to toxins in the liver, an effective detox agent). Damage to the brain/liver from alcohol, drugs, and cigarettes is also minimized by cysteine.