(2S)-2-[[(2S)-2-amino-4-hydroxy-4-oxobutanoyl]amino]-3-methylbutanoic acid;(2S)-2-[[(2S)-2-amino-4-hydroxy-4-oxo-butanoyl]amino]-3-methyl-butanoic acid;(2S)-2-[[(2S)-2-amino-4-hydroxy-1,4-dioxobutyl]amino]-3-methylbutanoic acid;(2S)-2-[[(2S)-2-amino-4-hydroxy-4-keto-butanoyl]amino]-3-methyl-butyric acid
(2S)-2-[[(2S)-2-amino-4-hydroxy-4-oxobutanoyl]amino]-3-methylbutanoic acid