Antimetabolite pathway enzymes

Antimetabolite pathway enzymes are a collective group of proteins essential for the biosynthesis of nucleic acids, primarily within the folate, purine, and pyrimidine metabolic pathways [1, 2]. Key enzymes in this category include dihydrofolate reductase (DHFR), thymidylate synthase (TS), ribonucleotide reductase (RNR), and various DNA polymerases [1, 4]. These enzymes are critical therapeutic targets because they facilitate the production of nucleotides required for DNA replication and RNA transcription, processes that are highly active in rapidly proliferating cells [2, 6]. Antimetabolite drugs, such as methotrexate, 5-fluorouracil, and gemcitabine, act as structural analogs of natural metabolites, allowing them to competitively inhibit these enzymes or be incorporated into nascent DNA/RNA strands [3, 4]. This interference leads to the depletion of nucleotide pools, induction of DNA damage, and ultimately, cell cycle arrest and apoptosis [2, 6]. Beyond their primary role in cancer treatment, these enzymes are also targeted to manage autoimmune diseases like rheumatoid arthritis and certain viral or bacterial infections [3, 4]. However, because these pathways are also active in healthy, rapidly dividing tissues, their inhibition frequently results in systemic toxicities, including myelosuppression and gastrointestinal distress [1, 7].

Other names

Nucleotide biosynthesis enzymesFolate metabolism enzymesPurine and pyrimidine synthesis enzymesDNA synthesis enzymesAntimetabolite targets

Antimetabolites target these enzymes by acting as structural analogs of natural substrates, leading to competitive inhibition of biosynthetic pathways, depletion of intracellular nucleotide pools, and incorporation into DNA or RNA to cause strand termination and apoptosis [2, 4, 6].