title: Competitive protein-binding assay for trimetrexate.
abstract: A competitive protein-binding assay has been developed for trimetrexate (TMTX) based on the tight binding of this drug to human dihydrofolate reductase (tetrahydrofolate dehydrogenase). In this assay, TMTX competes with 3H-methotrexate for binding to the enzyme. Free drug is separated from that bound to reductase by adsorption with dextran-albumin-coated charcoal. TMTX is measurable over a range from 2 X 10(-9) to 5 X 10(-8) M in plasma, with a coefficient of variation of less than 10%. Measurements of TMTX in plasma, cerebrospinal fluid, and urine agreed closely with parallel determinations in aqueous solutions.
authors.forename: J C
authors.initials: JC
authors.lastname: Drake
authors.forename: C J
authors.initials: CJ
authors.lastname: Allegra
authors.forename: G A
authors.initials: GA
authors.lastname: Curt
authors.forename: B A
authors.initials: BA
authors.lastname: Chabner
mesh_terms: D000818:Animals; D008297:Male; D051379:Mice; D011799:Quinazolines / Q000032:analysis*; D011869:Radioligand Assay; D013762:Tetrahydrofolate Dehydrogenase / Q000378:metabolism; D016597:Trimetrexate
chemical_list: D011799:Quinazolines; D013762:Tetrahydrofolate Dehydrogenase; D016597:Trimetrexate