Biochemical studies of a human low-activity galactose-1-phosphate uridyl transferase variant.
A low activity galactose-1-phosphate uridyl transferase (transferase) variant in a newborn infant has been demonstrated by biochemical studies in erythrocytes and cultured skin fibroblasts. The newborn infant was a galactosaemic suspect identified in a neonatal metabolic screening programme. On breast feeding, he did well without clinical symptoms of galactosaemia during the first 15 days of life. However, substantial amounts of erythrocyte galactose-1-phosphate and urinary galactitol corresponding to the levels in untreated galactosaemic patients, along with mild amino aciduria, were found. The transferase activity, as measured by a sensitive micro kinetic radioisotopic method, was about 7--10% of the normal. On starch gel electrophoresis, the enzyme from the haemolysate had similar mobility as the normal in Tris--glycine buffer, pH 8.8 and phosphate buffer, pH 7.0, but had a slower mobility than that of the normal in the histidine buffer, pH 7.8. The mobility difference was much clearer in a semipurified enzyme preparation. The transferase enzyme in the haemolysate appeared to be more heat labile.
D002478:Cells, Cultured; D004592:Electrophoresis, Starch Gel; D004912:Erythrocytes / Q000201:enzymology*; D005347:Fibroblasts / Q000201:enzymology; D005693:Galactosemias / Q000175:diagnosis* / Q000201:enzymology; D014644:Genetic Variation; D006801:Humans; D007231:Infant, Newborn; D007700:Kinetics; D008297:Male; D009713:Nucleotidyltransferases / Q000235:genetics*; D012867:Skin / Q000201:enzymology*; D006599:UDPglucose-Hexose-1-Phosphate Uridylyltransferase / Q000097:blood / Q000235:genetics*
D009713:Nucleotidyltransferases; D006599:UDPglucose-Hexose-1-Phosphate Uridylyltransferase