title: Kinetics and equilibria of pyrimidine nucleoside monophosphate kinase from human erythrocytes.
abstract: The common type of pyrimidine nucleoside monophosphate kinase (ATP:CMP phosphotransferase, EC 2.7.4.14), purified 50 000-fold from human erythrotes, reacted with a wide variety of nucleotides, but only ATP, dATP, UMP and CMP were good substrates. The optimum Mg2+ concentration, 2-3 mM, was generally independent of substrate concentration, of the nature of the substrate, and of the direction of the reaction. Kinetic studies indicated that a ternary complex was formed, that the substrates were bound at two unlike sites, and that the order of addition of substrates was random. Equilibrium constants were ATP + UMP 0.98, ATP + CMP 1.59, dATP + UMP 1.13, and ATP + AMP 1.20.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D003568:Cytidine Monophosphate / Q000378:metabolism; D003838:Deoxyadenine Nucleotides / Q000378:metabolism; D004912:Erythrocytes / Q000201:enzymology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008274:Magnesium / Q000378:metabolism; D009703:Nucleoside-Phosphate Kinase / Q000037:antagonists & inhibitors / Q000097:blood*; D010770:Phosphotransferases / Q000097:blood*; D011741:Pyrimidine Nucleosides / Q000097:blood*; D013379:Substrate Specificity; D014542:Uridine Monophosphate / Q000378:metabolism
chemical_list: D003838:Deoxyadenine Nucleotides; D011741:Pyrimidine Nucleosides; D000255:Adenosine Triphosphate; D014542:Uridine Monophosphate; D010770:Phosphotransferases; D009703:Nucleoside-Phosphate Kinase; D003568:Cytidine Monophosphate; D008274:Magnesium