Cystine

Cystine is the basic unit of protein. It is one of the 21 amino acids that make up human proteins. Except for the amino acids, the amino acids are sub-amino acids, and all other amino acids are & alpha; amino acids. The amino acids that make up the protein molecule are all L-amino acids, but it has been confirmed in recent years that they can be isomerized into D-amino acids, and the specific mechanism has not been studied.