Ribose-phosphate pyrophosphokinase, also known as Phosphoribosylpyrophosphate (PRPP) synthetase, is the key enzyme in the synthesis of purine and pyrimidine nucleotides. This protein is from E. coli.
The specific activity of PRPPS (19 umol/min /mg) was determined by the addition of 0.75 ug PPRS to a mixture of 1 mM ATP, 1 mM 5-phospho-D-ribose disodium, 10 mM KH
2PO
4 in 0.5 ml of 20 mM Tris-HCl (pH 8.0), 5 mM MgCl
2 at 36 C. Concentration changes of ATP and AMP were analysed by HPLC at 254 nm.