preferred_name: (2S,3R)-diaminobutanoate <=> (2S,3S)-diaminobutanoate
preferred_name_lc: (2s,3r)-diaminobutanoate <=> (2s,3s)-diaminobutanoate
label: (2S,3R)-diaminobutanoate <=> (2S,3S)-diaminobutanoate
label_lc: (2s,3r)-diaminobutanoate <=> (2s,3s)-diaminobutanoate