(2S,3S)-2-amino-3,4-dihydroxybutanoic acid (2S,3S)-2-amino-3,4-dihydroxy-butanoic acid (2S,3S)-2-amino-3,4-dihydroxy-butyric acid 21768-45-6 4-Hydroxy-L-threonine C06056 Hydroxythreonine L-Threonic acid, 2-amino-3,4-dihydroxy-, (S-(R*,R*))- alpha-Amino-beta,gamma-dihydroxybutyric acid