Improved microscale assay for purine phosphoribosyltransferase activities.

We describe an improved and rapid filter-type assay for purine phosphoribosyltransferase activities. 14C-labeled purine bases are used as substrates, and the equipment includes a sampling manifold and glass-fiber filters coated with polyethyleneimine-cellulose. The method is especially suited for assay of a large number of samples, and may be useful for other enzyme activity measurements.