Final answer:
6-mercaptopurine is converted in the body to 6-MP ribonucleotide, which inhibits the conversion of inosinic acid to adenine necessary for DNA synthesis. It can also lead to the production of faulty DNA and RNA, interfering with protein synthesis and cell division.
Step-by-step explanation:
6-mercaptopurine (6-MP) does not directly inhibit enzymes; rather, it is a precursor to a molecule that inhibits enzyme activity. Once inside the body, 6-MP is metabolized into its ribonucleotide form, 6-MP ribonucleotide, which is a potent inhibitor of the conversion of inosinic acid to adenine nucleotides. This inhibition is critical as adenine is a necessary component for DNA synthesis. The pathway is essential for cell proliferation, and disrupting it has therapeutic implications, especially in the treatment of certain types of cancers.In addition to its role in inhibiting the conversion of inosinic acid, 6-MP can also be incorporated into nucleic acids as thioguanosine. This leads to the production of faulty DNA and RNA molecules, which ultimately hampers proper protein synthesis and cell division. Equivalent mechanisms are seen with other antimetabolites, such as methotrexate inhibiting tetrahydrofolic acid formation, and hydroxyurea blocking thymidine incorporation into DNA.