Dehydrofolate reductase

Methotrexate (MTX, chemical structure shown in Fig. 1.) competitively inhibits the dehyrofolate reductase, an enzyme that plays an essential role in purine synthesis. The dehydrofolate reductase regenerates reduced folates when thymidine monophosphate is formed from deoxyuridine monophosphate. Without reduced folates cells are unable to synthesize thymine. Administration of N-5 tetrahydrofolate or N-5 formyl-tetrahydrofolate (folinic acid) can bypass this block and rescue cells from methotrexate activity by serving as antidote. 

Fig. 6.13 Measurement of FAC data for a range of pyrimethamine concentrations applied to sol-gel-entrapped dehydrofolate reductase (A) overlay of breakthrough curves and (B) nonlinear regression analysis of the fit to the measured breakthrough volumes from A [28]. Adapted with permission from the American Chemical Society.

Aminomutases (vitamin B12) 872, 874 8-Amino-7-oxo-nonanoate 718, 742 Aminopeptidase(s) 117, 609, 627 p-Aminopropionitrile 438 Aminopterin, inhibition of dehydrofolate reductase 805... 

As a case example we will consider the approach of van Breemen and co-workers (67-69), who applied pulsed ultrafiltration ESI-MS (70) to the screening for inhibitors of adenosine deaminase (67, 68) and dehydrofolate reductase (69). A schematic representation of the whole process is repiorted in Fig. 7.12. The authors used an HPLC/MS apparatus where the column was substituted with an ultrafiltration chamber (around 100 pL volume) equipped with a 10,000-MW cutoff membrane. Aqueous buffer solutions of the library components and the receptor were incubated, then loaded... 

G14. Grignani, F., Martelli, M. F., Tonato, M., and Finzi, A. F., Folate dependent enzymes in human epidermis Tetrahydro-folate dependent enzymes and relationship between dehydrofolate reductase and anethopterin. Arch. Dermatol. 96, 577-585 (1967). 

MC Ricci, RF Cross. Capillary electrophoresis separation of sulphonamides and dehydrofolate reductase inhibitors. J Microcol Sep 5 207-215, 1993. 

Center for Biologies Evaluation and Research Chinese hamster ovary capillary isoelectric focusing cytomegalovims cell specific perfusion rate dry cell weights dehydrofolate reductase Dulbecco s modified eagle medium... 

D-HPLC, see denaturating high-performance liquid chromatography DHFR (Dehydrofolate reductase) 725, 1079... 

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