title: Enzyme I of the phosphoenolpyruvate: sugar phosphotransferase system has two sites of phosphorylation per dimer.
abstract: Enzyme I of the phosphoenolpyruvate: sugar phosphotransferase system of Escherichia coli has been reported to contain one phosphorylation site per dimer and thus operates by either a half of the sites or a flip-flop mechanism [Misset, O., & Robillard, G. T. (1982) Biochemistry 21, 3136-3142; Hoving, T., ten Hoeve-Duurkens, R., & Robillard, G. T. (1984) Biochemistry 23, 4335-4340]. In this paper, the determination of two phosphorylation sites per dimer of enzyme I was made by using a number of different methods. In some experiments, less than two sites per dimer were found, but a concomitant loss in enzyme I activity was also found. The phosphorylated residue in enzyme I was shown to have the properties expected for a N3-phosphohistidinyl residue.
mesh_terms: D002021:Buffers; D004926:Escherichia coli / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D046911:Macromolecular Substances; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000302:isolation & purification / Q000378:metabolism*; D010750:Phosphoproteins / Q000032:analysis; D010761:Phosphorus Radioisotopes; D010766:Phosphorylation
chemical_list: D002021:Buffers; D046911:Macromolecular Substances; D010750:Phosphoproteins; D010761:Phosphorus Radioisotopes; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System