Radiochemical assay for determination of dihydropyrimidinase activity using reversed-phase high-performance liquid chromatography

A radiochemical assay was developed to measure the activity of dihydropyrim idinase (DHP) in human liver homogenates. The method is based on the separa tion of radiolabeled dihydrouracil from N-carbamyl-beta-alanine by HPLC wit h on-line detection of radioactivity combined with detection of (CO2)-C-14 by liquid scintillation counting. The assay was linear with time and protei n concentration. The minimum amount of radiolabeled products which could be determined proved to be 12 pmol using a purified stock solution of [2-C-14 ]-5,6-dihydrouracil. This highly sensitive assay is especially suitable to identify patients with a dihydropyrimidinase deficiency. (C) 1999 Elsevier Science B.V. All rights reserved.