(2S,3R)-diaminobutanoate <=> (2S,3S)-diaminobutanoate
(2s,3r)-diaminobutanoate <=> (2s,3s)-diaminobutanoate
(2S,3R)-diaminobutanoate <=> (2S,3S)-diaminobutanoate
(2s,3r)-diaminobutanoate <=> (2s,3s)-diaminobutanoate