Related Experiment Video
Updated: Sep 23, 2026

Multi-Gene Single Nucleotide Polymorphism Detection in Gastric Cancer Based on Ion Semiconductor Sequencing Platform
Published on: May 10, 2024
Dihydrofolate reductase mutant with exceptional resistance to methotrexate but not to trimetrexate
Pamela Pineda1, Aaron Kanter, R Scott McIvor
1Departments of Medicinal Chemistry and of Genetics and Development, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Abstract:
Two double (F31A/F34A, I60A/L67G) and one quadruple (F31A/F34A/I60A/L67G) mutant murine dihydrofolate reductases were constructed and evaluated for their ability to impart antifolate resistance. Both I60A/L67G and F31A/F34A/I60A/L67G were found to be unstable and devoid of catalytic activity. The K(i) values for F31A/F34A, methotrexate (MTX), bis-MTX, and PT-523 were found to be 10100-, 4410-, and 617-fold higher than the wild-type enzyme, respectively, but only 13.5-fold higher for trimetrexate (TMTX). These findings suggest that F31A/F34A could be used for gene therapy to render normal cells resistant to MTX but sensitive to TMTX.
Related Concept Videos
Pharmacogenetics of Drug Targets: β₂-Adrenergic Receptors, Apo E, Thymidylate Synthase
Treatment Resistant Cancers
Other Unique Bacteria
Antiprotozoal Agents
Drugs for Treatment of Crohn's Disease in IBD Using Immunomodulatory Agents
Phase II Reactions: Methylation Reactions
The mechanism of methylation unfolds in two stages. The first stage sees a methyltransferase enzyme facilitating the transfer of a methyl group from S-adenosylmethionine (SAM) to the substrate, forming S-adenosylhomocysteine (SAH). The second stage involves further metabolism of SAH into homocysteine, which can be recycled...
