Histidine (His, H)



  • basic, polar amino acid
  • usually coordinated at the imine nitrogen atom
  • Deprotonation of the second nitrogen atom is possible, allowing for a bridging coordination.
  • favored metal ions: Cu+, Zn2+, Cu2+, Fe2+
  • Histidine can only be synthesized by adult animal organisms.
  • For small children, it is considered an essential amino acid.