Chemical inhibitors of nm23-H5 can disrupt its function by targeting various aspects of nucleotide metabolism and DNA synthesis in which the protein is involved. Allopurinol, for example, inhibits xanthine oxidase, diminishing the production of substrates that are crucial for nm23-H5's nucleoside diphosphate kinase activity. This limitation of substrate availability directly impacts nm23-H5's capacity to maintain nucleotide balances required for DNA synthesis and repair. Similarly, Thiopurinol acts to decrease purine catabolism, which is expected to reduce the substrate pool for nm23-H5, thereby inhibiting its enzymatic function. Both 6-Thioguanine and 5-Fluorouracil are metabolized into nucleotide analogs that inhibit enzymes involved in the synthesis of DNA and RNA, which are substrates and potential interaction targets for nm23-H5. The integration of these analogs can disrupt the nucleic acid processes that nm23-H5 is associated with, thereby inhibiting its function.
Methotrexate and Azathioprine work by reducing the availability of purine nucleotides, which are essential for nm23-H5's kinase activity, through the inhibition of enzymes critical for purine synthesis. Mycophenolic acid and Ribavirin specifically target inosine monophosphate dehydrogenase, leading to reduced guanine nucleotides, which can impair the roles nm23-H5 plays in nucleotide metabolism. Hydroxyurea's inhibition of ribonucleotide reductase diminishes the deoxyribonucleotide pool, crucial for DNA synthesis, thus impacting nm23-H5's involvement in DNA replication and repair mechanisms. Cladribine, Clofarabine, and Fludarabine are nucleoside analogs that hinder DNA polymerases and other DNA-synthesizing enzymes, thereby interfering with DNA repair and synthesis pathways in which nm23-H5 participates. The incorporation of these analogs into DNA can lead to strand breaks or faulty DNA replication, which ultimately inhibits the function of nm23-H5, as it is unable to carry out its role effectively in the presence of these modified nucleotides.