GMP reductase
GMP reductase EC1.7.1.7 (Guanosine 5'-monophosphate oxidoreductase ) is an enzyme that catalyses the irreversible and NADPH-dependent reductive deamination of GMP into IMP.
NADPH + guanosine 5-phosphate = NADP + inosine 5-phosphate + NH3
It converts nucleobase, nucleoside and nucleotide derivatives of G to A nucleotides, and maintains intracellular balance of A and G nucleotides.