Determination of thymidine phosphorylase activity by a non-radiochemical assay using reversed-phase high-performance liquid chromatography.

Thymidine phosphorylase (TP) catalyses the conversion of thymidine into thymine. A non-radiochemical assay procedure for TP was developed in which thymine was detected at 265 nm after separation with reversed-phase HPLC. A complete separation of thymidine and thymine was achieved in 6 min and the minimum amount of thymine that could be detected was 0.8 pmol. The assay was linear with reaction times, up to at least 4 h, and protein concentrations up to at least 65 microg/ml. Population analysis showed no differences in TP activity between man and women or with increasing age.