A gouty family with increased phosphoribosylpyrophosphate synthetase activity: case reports, familial studies, and kinetic studies of the abnormal enzyme

Two male patients with urate overexcretion and clinical gout in a family showed activity of phosphoribosylpyrophosphate (PRPP) synthetase in erythrocyte lysates (3.1-fold) greater than that found in normal subjects. Hemolysates from 5 female persons in this family contained (2.7-fold) increased enzyme activity suggesting X-linked dominant transmission of the abnormality. Increased maximal velocity of the enzyme, aberrant protein pattern in polyacrylamide electrophoresis, and increased thermolability in purified enzyme suggested that this enzyme is a mutant one. From these findings, it was assumed that the characteristics of this enzyme were different from 4 previously reported enzymes.