Molecular model of Cysteine (C3. H7. NO2. S), a non-essential sulphur-containing amino acid in humans import an of protein synthesis, detoxification and diverse metabolic functions. Cysteine is a genetically coded amino acid, forming part of antioxidant gluthanione, compound that can be found in all tissues of the human body. The antioxidant activity of this component is attributed particularly to the presence of Cysteine in the compound. Atoms are represented as spheres and are colour-coded: carbon (black), hydrogen (white), nitrogen (blue) and oxygen. Illustration.