The purine ring system is shown below.What is the source of the nitrogen atoms 3 and 9 during the de novo biosynthesis of purines?

Question

Quizplus · Accepted Answer

Nitrogen atoms 3 and 9 of the purine ring system are derived from the amide nitrogen of glutamine. During de novo purine biosynthesis, nitrogen atoms are contributed by various nitrogen-containing compounds, including glycine, aspartate, and glutamine. However, in the purine ring system, the source of nitrogen atoms 3 and 9 is specifically glutamine.

The Purine Ring System Is Shown Below