European Journal of Biochemistry · 1979 · 30 citations · 12 references
Life SciencesBiochemistryBiophysicsBiocatalysisEnzymologyMembrane BiochemistryBioinorganic ChemistryCatalytic MechanismsEnzyme CharacterizationEnzyme InhibitionEnzyme KineticsEnzyme StabilityEnzyme Kinetics AssaysEnzyme Kinetics ImagingHeat InactivationMagnesium BiochemistryMagnesium CatalysisMagnesium Coordination In BiomoleculesMagnesium Ion DependenceMagnesium-dependent Catalysis
The membrane-bound inorganic pyrophosphatase (EC 3.6.1.1) from Rhodospirillum rubrum has been investigated with the tools of enzyme kinetics, and with two amino acid reagents, N-ethyl-maleimide (MalNET) and 4-chloro-7-nitrobenzofurazan (Nbf-Cl). 1. The concentration of the true substrate, MgPPi, was varied with constant concentrations of free Mg2+ or PPi. It was observed that Mg2+ acted as an activator. 2. Heat inactivation of the enzyme at 62 degrees C was slowed down in the presence of Mg2+. 3. MalNET and Nbf-Cl bind to the enzyme, and inhibit its activity. The effect of both reagents is dependent on the temperature. 4. A model is proposed where the 1:1 complex of Mg2+:PPi acts as substrate and Mg2+ interacts directly with the enzyme as an activator. PPi can bind to the enzyme, but is not hydrolyzed in the uncomplexed form.
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The reactivity of SH groups with a fluorogenic reagent
Donald Birkett, Nicholas C. Price, G. K. Radda et al. · FEBS Letters · 1970 · 178 citations
Herrick Baltscheffsky, Lars‐Victor von Stedingk · Biochemical and Biophysical Research Communications · 1966 · 86 citations