polar amino acid Any amino acid whose side chain is capable of forming one or more hydrogen bonds. polar amino-acids PMID:12016058 CHEBI:8283 polar amino acids polar amino-acid 74.059 0 OC(C(*)N)=O CHEBI:26167 MetaCyc:Polar-amino-acids 74.02420 chebi_ontology C2H4NO2R polar amino acid amino acid polar amino acid zwitterion