RT Journal Article
SR Electronic
T1 A radioimmunoassay for 5-methyltetrahydrohomofolate.
JF Journal of Pharmacology and Experimental Therapeutics
JO J Pharmacol Exp Ther
FD American Society for Pharmacology and Experimental Therapeutics
SP 344
OP 347
VO 218
IS 2
A1 K L Fong
A1 D H Ho
A1 R S Benjamin
A1 F Yang
A1 J Sickler
A1 N S Brown
A1 G P Bodey
YR 1981
UL http://jpet.aspetjournals.org/content/218/2/344.abstract
AB A radioimmunoassay for 5-methyltetrahydrohomofolate has been developed by using antibody induced in rabbits by 5-methyltetrahydrohomofolate-bovine serum albumin conjugates. The labeled drug was prepared by condensing it with [3H]histamine or [125I]histamine. The assay employing either isotope was simple and reproducible and had identical sensitivities. The specificity of the antibody was characterized by comparing the effectiveness of various related compounds in displacing labeled 5-methyltetrahydrohomofolate from the binding site of the antisera. At concentrations up to 1000 microgram/ml, homofolate acid, tetrahydrohomofolic acid, folic acid and methotrexate showed no competition for the binding. 5-methyltetrahydrofolic acid and 5-formyltetrahydrofolic acid cross-reacted with the antisera; the concentrations producing 50% binding inhibition were 2.8 and 24 microgram, respectively, as compared to 0.01 microgram for 5-methyltetrahydrohomofolate. The assay can be used for measuring the drug in plasma and tissues. This study supports its usability for clinical pharmacologic studies.