Purine nucleoside-processing enzymes

Purine nucleoside-processing enzymes are a group of enzymes essential for the synthesis and recycling of purine nucleotides, which serve as the building blocks for DNA and RNA synthesis (StatPearls, 2023). This group includes key therapeutic targets such as purine nucleoside phosphorylase (PNP), adenosine deaminase (ADA), and inosine monophosphate dehydrogenase (IMPDH) (Schramm, 2011). These enzymes are critical for maintaining the balance of intracellular nucleotide pools; for instance, PNP is vital for the salvage pathway, and its inhibition leads to the toxic accumulation of deoxyguanosine triphosphate (dGTP) in T-cells (Gandhi et al., 2005). Consequently, these enzymes are targeted in the treatment of T-cell malignancies, autoimmune diseases, and for immunosuppression in organ transplantation (PubChem, 2024). Drugs like forodesine (a PNP inhibitor) and mycophenolate mofetil (an IMPDH inhibitor) exploit the high dependency of rapidly dividing cells on these pathways to arrest cell growth and induce apoptosis (UniProt, 2024). The selective toxicity towards lymphocytes makes these enzymes particularly attractive for treating hematological cancers and preventing graft rejection.

Other names

Purine metabolic enzymesPurine salvage pathway enzymesPurine biosynthetic enzymesNucleoside processing enzymes

Inhibition of purine nucleotide synthesis and salvage pathways, leading to the depletion of intracellular nucleotide pools (such as ATP and GTP) or the toxic accumulation of metabolites (such as dGTP), which subsequently inhibits DNA and RNA polymerases, arrests the cell cycle, and induces apoptosis.