has part has part has_part has role has role is conjugate base of is conjugate acid of polar amino acid threonine Threonin An α-amino acid in which one of the hydrogens attached to the α-carbon of glycine is substituted by a 1-hydroxyethyl group. chebi_ontology CHEBI:26986 threoninate threoninium 2-amino-3-hydroxybutanoic acid 1-hydroxyethyl group Daphnia magna metabolite