Dihydrofolate reductase, or DHFR, is an enzyme that reduces dihydrofolic acid to tetrahydrofolic acid, using NADPH as electron donor, which can be converted to the kinds of tetrahydrofolate cofactors used in 1-carbon transfer chemistry. In humans, the DHFR enzyme is encoded by the DHFR gene. It is found in the q11→q22 region of chromosome 5.
Bacterial species possesses distinct DHFR enzymes (based on their pattern of binding diaminoheterocyclic molecules), but mammalian DHFRs are highly similar. The plasmid-encoded DHFR (R67 dihydrofolate reductase) shows a high level of resistance to the antibiotic trimethoprim. It is a homotetramer with an unusual pore, which contains the active site, passing through the middle of the molecule. Its structure is unrelated to that of chromosomal DHFRs.
Read more about Dihydrofolate Reductase: Structure, Function, Mechanism, Biological Function, Clinical Significance, Therapeutic Application and Disease Relevance, Application As A Research Tool, Interactions, Interactive Pathway Map