Step 8. Elimination of fumarate is catalyzed by lyase. The carbon skeleton of aspartate is lost as fumarate (only the amino group is contributed by aspartate).

Enzyme: adenylsuccinate lyase

Step 9: The second formyl group is added from N¹⁰ -formyltetrahydrofolate:

Enzyme: AICAR transformylase

Step 10: Cyclization/dehydration produces inosinate:

Formation of AMP and GMP from IMP

IMP is a common precursor to both AMP and GMP.

1. Formation of adenylate (AMP): the C-6 carbonyl group of inosinate is replaced with the amino

group from Asp.