Biochemical Journal · 1986 · 17 citations · 8 references
Life SciencesBiochemistryMolecular BiologyEnzyme MechanismEnzymologyMetabolic RegulationCatalytic MechanismsEnzyme BiophysicsEnzyme CharacterizationEnzyme KineticsEnzyme RegulationYeast BiologyExponential MechanismPh Dependence Of CatalysisPh Dependence Of Enzyme ActivityPh Effects On Enzyme ActivityPyruvate Kinase RegulationPyruvate MetabolismRegulation Of Enzyme Activity By PhosphorylationYeast Metabolism
The kinetics of pyruvate kinase from Saccharomyces cerevisiae were studied at 25 degrees C as a function of the concentrations of the substrates ADP, phosphoenolpyruvate and Mg2+ and the effector H+ in the pH range 5-6.6. The enzyme was activated by 100 mM-K+ and 32 mM-NH4+ throughout. It was found that the data could be described by the exponential model for a regulatory enzyme. On that basis, it was concluded that the binding of H+ is positively interactive and that the protonated enzyme is catalytically inactive. It was also found that H+ interacts positively with phosphoenolpyruvate but negatively with both ADP and Mg2+.
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Ravindra Kumar Gupta, Albert S. Mildvan · Journal of Biological Chemistry · 1977 · 67 citations · Full text