Question

Explain how the pathways involved in the formation of AMP and GMP and IMP are able to self-regulate and maintain an appropriate balance between two products.

Answer 1

The major synthesis pathway of purine nucleotides is de novo synthesis. The committed step in de novo synthesis is the 1st step catalyzed by amidotransferase.it is inhibited by AMP and GMP.They act as allosteric modifiers. Binding of AMP and GMP on the enzyme converts monomeric active form to a dimeric inactive form.Since both AMP and GMP can bind to the same enzyme molecule at different sites, they act synergistically.Both AMP and GMP inhibit their own formation by feedback inhibition of adenylosuccinate synthetase and IMP dehydrogenase.