Specificity of Mouse Uridine Phosphorylase

Chemicals-Uridineand deoxyuridine were obtained from the California Corporation for Biochemical Research; thymidine and ammonium sulfate (special enzyme grade) from the Mann Research Laboratories, and DEAE-cellulose from Eastman Organic Chemicals.Enzyme Assays-The final assay solution, incubated at 37", contained 10 mM nucleoside substrate in 0.1 M sodium phosphate buffer at pH 7.4, and an amount of enzyme which kept the cleavage as close to the linear range as possible.At 0 minute