Folate, or vitamin B9, is another essential nutrient involved in DNA synthesis and repair. It is converted into its active form, tetrahydrofolate (THF), which acts as a coenzyme in various one-carbon transfer reactions. These reactions are critical for the synthesis of purines and pyrimidines, the building blocks of DNA. Enzymes such as thymidylate synthase, which catalyzes the conversion of dUMP to dTMP, rely on THF. A deficiency in folate disrupts these catalytic processes, resulting in defective DNA synthesis and megaloblastic anemia.
