Abstract
An enzymatic method for determination of 5-phosphoribosylpyrophosphate (PRPP) was investigated. The method was based on a coupled reaction of orotidine-5'-monophosphate pyrophosphorylase and orotidine-5'-monophosphate decarboxylase obtained as cell-free extract from a mutant strain of Micrococcus glutamicus (Syn. Corynebacterium glutamicum). The enzymes catalyzed quantitative conversion of orotic acid to uridine-5'-monophosphate. In the method, the consumption of orotic acid was determined by measuring optical density at 295mμ and then PRPP was calculated from the amount of orotic acid consumed. The conditions of the enzyme reaction were examined in detail, and a modified method for determination of PRPP involving termination of the enzyme reaction by EDTA was est-ablished. According to the present method, 10-1 μmol. of PRPP is determined with ac-curacy of 100±3% within 30 minutes. As an application of the method, chemical stability of PRPP was examined and the results were described.
