Dihydrofolate Reductase Tour
Dihydrofolate Reductase (DHFR) is a housekeeping enzyme found in all cells. DHFR catalyzes the NADPH dependent reduction of 7,8-Dihydrofolate to 5,6,7,8-dihydrofolate reductase. The DHFR shown here has been isoloated from Escherichia Coli. It is comprised of two identical chains each of which has 159 residues and a molecular weight of approximately 18KDa. More infomation about this structure can be found by going to the RCSB Protein Data Bank link below. The buttons below should be pressed in sequential order for proper viewing.
DHFR is a monomeric protein containing a mixed eight-stranded beta-sheet (yellow). The sheet is flanked by four alpha helices
All strands are parallel except for the C terminal strand which is antiparallel (shown in green)
The NADP is held in the DHF by two of the alpha helices in the protein.
Take a closer look at the interactions between the NADP and the residues of the helices
5,6-dihydrofolate is reduced to 5,6,7,8-tetrahydrofolate reductase by NADPH within the DHF enzyme. A hydride ion is directly transferred from the nicotinamide ring of NADPH to the pteridine ring of dihyrofolate folate. The hydride is transferred from the C4 position of the nicotinamide ring shown in yellow to a carbon and nitrogen on the pteridine ring shown in green and magenta respectively.
View these within the context of the protein.
Final view of the entire complex including NADPH and folate.
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