L-Cystine It is a white solid that is slightly soluble in water.It is common in many foods such as eggs, meat, dairy products, and whole grains as well as skin, horns and hair.
Cystine is the oxidized dimer form of the amino acid cysteine and has the formula (SCH2CH(NH2)CO2H)2 It serves two biological functions: a site of redox reactions and a mechanical linkage that allows proteins to retain their three-dimensional structure.