(2S)-2-amino-3-oxopropanoic acid (2S)-2-amino-3-oxo-propanoic acid (2S)-2-amino-3-keto-propionic acid 2-Aminomalonate semialdehyde 2-Ammoniomalonate semialdehyde C11822 3-oxo-L-alanine CHEBI:37012 L-alpha-formylglycine