DNA polymerase and de novo purine synthesis enzymes

DNA polymerase and de novo purine synthesis enzymes represent a critical metabolic and replicative axis targeted by antimetabolite chemotherapy. DNA polymerases are the primary enzymes responsible for the high-fidelity replication of the genome, while the de novo purine synthesis pathway provides the necessary nucleotide building blocks, such as adenosine and guanosine, from simple precursors [1, 4]. This dual-target approach is exemplified by purine analogs like 6-mercaptopurine and fludarabine, which disrupt cellular homeostasis by both starving the cell of nucleotides and directly interfering with DNA strand elongation [3, 5]. By inhibiting these processes, these drugs effectively halt the proliferation of rapidly dividing cells, which is the basis for their use in treating various leukemias and autoimmune conditions [1]. However, the lack of absolute specificity for malignant cells leads to significant side effects, most notably bone marrow suppression and gastrointestinal distress [5]. Monitoring of metabolic enzymes like TPMT is often required to manage toxicity and optimize dosing for patients receiving these therapies [5].

Other names

Purine antimetabolite targetsNucleotide metabolism and DNA replication enzymesThiopurine targets

Drugs targeting this complex system act as antimetabolites. Purine analogs like 6-mercaptopurine are converted into thio-nucleotides that inhibit the rate-limiting enzyme of de novo purine synthesis, glutamine-phosphoribosylpyrophosphate amidotransferase [3, 5]. Additionally, these fraudulent nucleotides are incorporated into DNA, where they inhibit the activity of DNA polymerases, leading to chain termination or the induction of DNA damage responses and apoptosis [1, 2].