Nitrogen-9 of purine ring is provided by ?
Glycine
Aspaate
Glutamine
CO2
In de novo synthesis, purine ring is formed from variety of precursors is assembled on ribose-5-phosphate. Precursors for de novo synthesis are - i) Glycine provides C4, C5 and N7 ii) Aspaate provides N1 iii) Glutamine provides N3 and N9 iv) Tetrahydrofolate derivatives furnish C2 and C8 v) Carbon dioxide provides C6