Abstract
A precise, specific assay for the 4-amino analogues of folic acid in urine, serum and tissues has been described. The method is based on the stoichiometric inhibition of the enzyme folic acid reductase by these drugs. A titration of drug with enzyme is measured by a colorimetric determination (Bratton-Marshall reaction) of the diazotizable p-aminobenzoylglutamate
derived from the enzymic product, tetrahydrofolate. This method is specific for the unaltered form of these drugs and is free from interference by the presence of growth factors such as folic acid, folinic acid or thymine. The quantitative determination of folic acid by the measurement of diazotizable amine following complete reduction of the substrate by the enzyme has also been demonstrated.
Footnotes
- Received March 15, 1962.
JPET articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|