Tags: Chemical Compound, Chemical Substance.
Cystine is the amino acid formed by the oxidation of two cysteine molecules that covalently link via a disulfide bond. This organosulfur compound has the formula (SCH2CH(NH2)CO2H)2. It is a white solid that is slightly soluble in water. Human hair and skin contain approximately 10-14% cystine by mass. It was discovered in 1810 by William Hyde Wollaston but was not recognized as being derived of proteins until it was isolated from the horn of a cow in 1899.
