histidine histidinium(1+) [NH3+]C(Cc1c[nH]c[nH+]1)C([O-])=O chebi_ontology HNDVDQJCIGZPNO-UHFFFAOYSA-O InChI=1S/C6H9N3O2/c7-5(6(10)11)1-4-2-8-3-9-4/h2-3,5H,1,7H2,(H,8,9)(H,10,11)/p+1 histidine monocation +1 histidinium(1+) 2-ammonio-3-(1H-imidazol-3-ium-4-yl)propanoate 156.07675 156.16262 CHEBI:32531 C6H10N3O2 histidinium histidinium(2+) alpha-amino-acid cation