pyrophosphate and Purine-Pyrimidine-Metabolism--Inborn-Errors

Deficient hypoxanthine-guanine phosphoribosyl transferase (HGPRT; EC 2.4.2.8) enzymes from erythrocytes of patients with hyperuricemia and with the Lesch-Nyhan syndrome migrate 15% faster in polyacrylamide gel disc electrophoresis than the normal enzyme. A half-sister of two males with partial deficiency, who had 34% of normal HGPRT activity in her erythrocytes, yielded profiles containing two distinct zones of activity; one corresponded to the enzyme found in normal individuals and one to the variant of her half-brothers. However, in her profile her variant enzyme showed notably greater activity than that observed in her half-brothers. This increase was due to an activation of the variant by normal enzyme. Electrophoresis of mixtures of normal enzyme with partially deficient enzymes from patients with hyperuricemia and with the Lesch-Nyhan syndrome also led to activation of deficient HGPRT variants by normal enzymes. Deficient variants were also activated by normal enzyme on filtration through Sephadex G-25. Experiments in which deficient variant enzymes were activated with purified normal enzyme labeled with (125)I indicated that deficient enzymes incorporate components of the normal enzyme. No such activation of deficient enzymes was ever obtained when mixtures of deficient and normal enzymes were put together in a test tube.

Topics: Athetosis; Carbon Isotopes; Chromatography, Gel; Diphosphates; Electrophoresis, Disc; Enzyme Activation; Erythrocytes; Female; Genetic Code; Genetic Variation; Guanine; Heterozygote; Humans; Hypoxanthines; Intellectual Disability; Iodine Isotopes; Isoenzymes; Lesch-Nyhan Syndrome; Male; Pentosephosphates; Pentosyltransferases; Purine-Pyrimidine Metabolism, Inborn Errors; Ribose; Self Mutilation; Sex Chromosomes; Uric Acid

Topics: Allopurinol; Diphosphates; Guanine; Humans; Hypoxanthines; Nucleotides; Purine-Pyrimidine Metabolism, Inborn Errors; Purines; Pyrimidines; Transferases; Uric Acid; Xanthine Oxidase

Hypoxanthine-guanine phosphoribosyltransferase is virtually inactive in erythrocytes from patients with the classical Lesch-Nyhan syndrome. In one such patient, activity of this enzyme ranged from 8 to 34 percent of normal in erythrocytes when assayed with a very high concentration of magnesium 5-phosphoribosyl-1-pyrophosphate. In addition, the mutant enzyme exhibited sigmoidal kinetics with this substrate as well as an increased Michaelis constant for both guanine and hypoxanthine. These findings provide the first evidence for genetic heterogeneity within the group of patients with the Lesch-Nyhan syndrome.

Topics: Athetosis; Child; Chorea; Compulsive Behavior; Diphosphates; Erythrocytes; Guanine; Humans; Hypoxanthines; Intellectual Disability; Kinetics; Male; Molecular Biology; Mutation; Purine-Pyrimidine Metabolism, Inborn Errors; Self Mutilation; Transferases; Uric Acid

Topics: Adenine; Athetosis; Diphosphates; Erythrocytes; Humans; Hypoxanthines; Intellectual Disability; Lesch-Nyhan Syndrome; Purine-Pyrimidine Metabolism, Inborn Errors; Self Mutilation; Transferases

Topics: Allopurinol; Athetosis; Basal Ganglia; Diphosphates; Erythrocytes; Fibroblasts; Guanine; Humans; Hypoxanthines; Infant; Intellectual Disability; Lesch-Nyhan Syndrome; Liver; Pentosephosphates; Purine-Pyrimidine Metabolism, Inborn Errors; Purines; Ribose; Self Mutilation; Transferases; Xanthines

IMP:pyrophosphate phosphoribosyltransferase (IPPase) (EC 2.4.2.8) has been purified over 7000-fold from human erythrocytes. The purified enzyme moved as a single band on disc electrophoresis. Antisera prepared in rabbits and rats against the purified enzyme precipitated and neutralized the enzyme, but had no effect on AMP-pyrophosphate phosphoribosyltransferase (EC 2.4.2.7) activity. Evidence was found for isozymes (enzyme variants) of IPPase in normal erythrocytes. Erythrocyte lysates of five patients with Lesch-Nyhan disease reacted with antisera against normal IPPase. Lysates from LN erythrocytes blocked the inactivation of normal enzyme by the antibody. LN erythrocytes had about the same concentration of enzyme protein as normal erythrocytes. The genetic defect in LN results in the production of essentially normal amounts of an immunologically identifiable but catalytically incompetent enzyme. Thus LN is apparently the result of a mutation in a structural gene and is not due to deletion of a structural gene or defect in a regulatory gene.

Topics: Adenine Nucleotides; Animals; Athetosis; Carbon Isotopes; Chemical Precipitation; Chromatography, DEAE-Cellulose; Chromatography, Gel; Cross Reactions; Diphosphates; Drug Stability; Electrophoresis, Disc; Erythrocytes; Genes; Hot Temperature; Humans; Hypoxanthines; Immune Sera; Infant; Intellectual Disability; Isoenzymes; Lesch-Nyhan Syndrome; Mutation; Neutralization Tests; Nucleotides; Pentosephosphates; Purine-Pyrimidine Metabolism, Inborn Errors; Quaternary Ammonium Compounds; Rabbits; Rats; Self Mutilation; Sulfates; Transferases

Topics: Allopurinol; Diphosphates; Erythrocytes; Gout; Humans; Purine-Pyrimidine Metabolism, Inborn Errors; Purines; Ribose; Transferases; Uric Acid

Topics: Adult; Diphosphates; Erythrocytes; Glucosyltransferases; Gout; Guanine; Hot Temperature; Humans; Hypoxanthines; In Vitro Techniques; Leukocytes; Male; Middle Aged; Molecular Biology; Mutation; Purine-Pyrimidine Metabolism, Inborn Errors; Uric Acid