Effect of allopurinol and oxipurinol on pyrimidine synthesis in cultured human fibroblasts

Dietary-Induced Variation of Hypoxanthine-Guanine Phosphoribosyl Transferase Activity in Patients with the Lesch-Nyhan Syndrome

“…Background (150-250 cpm) was defined by the radioactivity migrating with carrier GMP after incubation of a dialysed preparation of hemolysate with a reaction mixture which was complete except for the absence of PPribose-P. Each increment in specific activity of 0.001 nmol/ mg per h represented 75 counts above background. Orotate phosphoribosyltransferase (OPRT), and orotidylic decarboxylase (ODC) were assayed as described previously (10,11).…”

Mechanism of allopurinol-mediated increase in enzyme activity in man

“…OPRT was assayed by a microradiochemical method described previously in which the conversion of orotic acid-6-"C to OMP-6-"C is determined in the presence of 6-azauridylic acid, PP-ribose-P, and magnesium (7). Using this assay the formation of OMP was linear with respect to time and protein concentration and under all conditions less than 6%o of the labeled OMP was converted to UMP.…”

Hereditary Orotic Aciduria: Evidence for a Structural Gene Mutation

“…Cell lysates from confluent monolayers were prepared as reported (14). After centrifugation at 600 X g to remove cellular debris, the lysates were passed through individual Sephadex G-25 columns with a bed volume of 1.5 ml and a void volume of 0.6 ml.…”

“…ODC was assayed according to Kelley and Beardmore (15). The assay for OPRT (14) was modified to measure 14CO2 instead of the formation of orotidine-5'-monophosphate (OMP). The reaction was initiated by addition of [7-14C]orotic acid, and the tubes were incubated at 370 for 60 min.…”