Purification and characterization of human erythrocyte uridylyl transferase.
A new method for the purification of human erythrocyte uridylyl transferase (UDPglucose: alpha-D-galactose-1-phosphate uridylyltransferase EC 2.7.7.12) is described. It consists of a hydrophobic purification step associated with hydroxyapatite chromatography and provided for the first time a purification of more than 45 000-fold with a high activity (15 I.U/mg) and a yield of 32%. We show that the enzyme is a dimer and has a molecular weight of 88 000. It can be resolved into three bands by isoelectric focusing with an apparent pI between 5.0 and 5.4. It could be shown by steady-state initial rate measurements that the interconversion of the two substrates of human transferase (Gal-1-P and UDP-glucose) follows ping-pong bi-bi kinetics, with Km values of 0.2 and 0.065 mM, respectively.
D004912:Erythrocytes / Q000201:enzymology*; D006801:Humans; D007700:Kinetics; D046911:Macromolecular Substances; D008970:Molecular Weight; D009713:Nucleotidyltransferases / Q000097:blood*; D013696:Temperature; D006599:UDPglucose-Hexose-1-Phosphate Uridylyltransferase / Q000097:blood* / Q000302:isolation & purification
D046911:Macromolecular Substances; D009713:Nucleotidyltransferases; D006599:UDPglucose-Hexose-1-Phosphate Uridylyltransferase