1 Z17 (3r)-3-(7-amino-1-methyl-4,5-dioxo-1,4,5,6-tetrahydropyrimido[4,5-C]pyridazin-3-yl)butanoic acid 1.000 2 0J2 (3r)-3-(7-amino-4,5-dioxo-1,4,5,6-tetrahydropyrimido[4,5-C]pyridazin-3-yl)butanoic acid 0.950 3 Z25 3-(7-amino-4,5-dioxo-1,4,5,6-tetrahydropyrimido[4,5-C]pyridazin-3-yl)propanoic acid 0.900 4 0HY Methyl (3r)-3-(7-amino-4,5-dioxo-1,4,5,6-tetrahydropyrimido[4,5-C]pyridazin-3-yl)butanoate 0.818 5 B52 (2r)-2-(7-amino-1-methyl-4,5-dioxo-1,4,5,6-tetrahydropyrimido[4,5-C]pyridazin-3-yl)propanoic acid 0.773 6 0J4 (2r)-2-(7-amino-4,5-dioxo-1,4,5,6-tetrahydropyrimido[4,5-C]pyridazin-3-yl)propanoic acid 0.727