Simplex Optimization for the Simultaneous HPLC Assay of the Activities of Purine-Nucleoside Phosphorylase and Hypoxanthine-Guanine Phosphoribosyl Transferase

Abstract

The modified sequential simplex procedure is shown to be effective for maximizing a complex enzyme assay. The optlmum levels for two factors, pH and substrate concentration, for a coupled enzyme assay of hypoxanthine-quanlne phosphor Ibosy I-transferase (HGPRTase) and purine nucleoside phosphorylase (PNPase) were found by searching a factor space made up of these variables. The performance Index or response to be optimized was a function of the product of the two single activities. The maximum activity for this function was found at a pH of 7.9 and a concentration of Inosine in the reaction mix of 0.84 mM.