(2S)-2-azaniumyl-4-oxo-4-phosphonatooxybutanoate (2S)-2-azaniumyl-4-oxo-4-phosphonatooxy-butanoate (2S)-2-ammonio-4-oxo-4-phosphonatooxybutanoate (2S)-2-ammonio-4-keto-4-phosphato-butyrate L-Aspartate-4-phosphate nchembio842-comp2