Space-filling model of the L -histidine molecule, C ₆ H ₉ N ₃ O ₂ , in the zwitterionic form found in the crystal structure determined by X-ray diffraction and reported in Cryst. Growth Des. (2020), 20 , 7788-7804 ( CSD entry KAGGEI ).

Colour code:

Carbon, C: grey

Hydrogen, H: white

Nitrogen, N: blue

Oxygen, O: red