Cystine is an essential amino acid that contains two cysteine molecules joined by a disulphide bond. This bonds many poisons of the body, acts as an antidote (in the process of detoxification). In combination with glycine and glutamine is involved in the synthesis of glutathione. Cystine is present in the vegetable protein products (corn, peanut), and in available concentrates and whey protein isolates, as well as other amino acids.