[Isoenzymes of purine phosphoribosyltransferases in erythrocytes of Lesch-Nyhan patients (author's transl)].

vIsoenzymes of purine phosphoribosyltransferases in erythrocytes of Lesch-Nyhan patients The activities of the purine phosphoribosyltransf erases were determined in the hemoly sates of two Lesch—Nyhan patients. In the hemolysates of both patients hypoxanthine-guanine phosphoribosyltransferase activities were decreased to 5% and 1% of the normal value respectively. Adenine phosphoribosyltransferase activities were increased by 29% and 74% respectively. The combination of disc-electrophoresis on polyacrylamide gel with the radiochemical test made it possible to separate and quantitate the purine phosphoribosyltransferase isoenzymes in hemolysates. 4 isoenzymes of hypoxanthinerguanine phosphoribosyltransferase and 3 isoenzymes of adenine phosphoribosyltransferase could be demonstrated. There were no differences between the migration of the isoenzymes of both enzymes in the hemolysates of the Lesch—Nyhan patients and the hemolysate of the normal patient. Both Lesch—Nyhan patients showed an incomplete hypoxanthine-guanine phosphoribosyltransferase isoenzyme profile (patient H. H.: no isoenzyme 1; patient . .: no isoenzyme 2). The absence of different isoenzyme activities in both patients provides evidence for a heterogeneity of the mutation responsible for the enzyme deficiency in the Lesch—Nyhan syndrome. The adenine phosphoribosyltransf erase isoenzymes showed alterations in their activities in both cases at Lesch—Nyhan syndrome: In both Lesch—Nyhan patients, the activity of isoenzyme I in patient H. H. increased approximately 6-fold and the activity of the isoenzyme II was about twice that in the hemolysate of the control person.