A mutant adenine phosphoribosyltransferase in 2,8-dihydroxyadenine urolithiasis

In one case of 2,8-dihydroxyadenine urolithiasis, reduced adenine phosphoribosyltransferase activity was found. The patient's enzyme had normal affinity for adenine but reduced affinity for substrate phosphoribosyl-pyrophosphate. It was much more stable at 60 degrees C than control. It seems that erythrocyte adenine phosphoribosyltransferase obtained from the patient may be a variant enzyme.