Phosphoribosyl pyrophosphate synthetase, increased

In some cases of gout a twofold increased activity of the phosphoribosyl pyrophosphate synthetase has been demonstrated in fibroblasts with increased production of PRPP. The possibility of an inhibitor causing the increased activity was excluded. This is another example of an enzyme increase in hereditary disease [217]. 

Two enzyme abnormalities resulting in an overproduction of uric acid have been well described (Fig. 91-1). The first is an increase in the activity of phosphoribosyl pyrophosphate (PRPP) synthetase, which leads to an increased concentration of PRPP. PRPP is a key determinant of purine synthesis and thus uric acid production. The second is a deficiency of hypoxanthine guanine phosphoribosyl transferase (HGPRT). 

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