Quantification of telomerase activity by direct scintillation counting

An improved telomerase assay was developed that allows direct quantification of the enzyme activity by scintillation counting of the labeled telomerase product. The assay measures the incorporation of ³²P-dGTP into telomeric repeats synthesized at the 3′ end of a biotinylated primer. Telomerase reaction product is separated from the reaction mix by streptavidin-coated magnetic beads and counted. The assay can be used for quantitative studies of human telomerase and its inhibitors.