E920

E920 (L-cysteine) L-cysteine is an optically active L-form of cysteine. It is obtained industrially from animal products (keratin), but can also be obtained by hydrolysing human hair. Cysteine is the α-mercaptomethyl (α-thiomethyl)-substituted amino acid of proteins. It is an α-amino acid. Amino acids play a key metabolic function in the human...