(2S)-2-amino-3-(2,6-dioxo-3H-pyrimidin-1-yl)propanoic acid (2S)-2-amino-3-(2,6-diketo-3H-pyrimidin-1-yl)propionic acid 21381-33-9 C08289 Isowillardiine alpha-Amino-3,6-dihydro-2,6-dioxo-1(2H)pyrimidinepropanoic acid beta-(2,4-Dihydroxypyrimidin-3-yl)alanine