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Mechanism of the Magnesium Ion Activation of the Catalytic Activity of Horse Liver Aldehyde Dehydrogenase

  • Kojiro Takahashi
  • Carolyn S. Brown
  • Henry Weiner

Abstract

The activity of the pI 5 isozyme of horse liver aldehyde dehydrogenase is markedly enhanced by some divalent metal ions (Ca, Mn, Mg), inhibited by others (Fe, Cu, Cd), totally inhibited by Hg, and not significantly affected by still others (Zn, Ni, Co). Steady-state kinetics show that with 0.5 mM Mg or Mn a 2-fold activation of the velocity measured at pH 7.5 occurs when propionaldehyde is the substrate. In the pre-steady state, the magnitude burst of NADH formulation is increased from 2 moles formed per mole of tetrameric enzyme to 4 moles formed in the presence of Mg. The stoichiometry of coenzyme (NADH, NAD, ε-NAD) binding is also increased from essentially 2 moles binding to 4 moles binding per mole enzyme in the presence of Mg. It appears that the enzyme exhibits half of the site reactivity in the absence of metal but has a full complement of catalytic sites in the presence.

Keywords

Aldehyde Dehydrogenase Scatchard Plot Tetrameric Enzyme Mole Enzyme Scientist Development Award 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

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Copyright information

© Springer Science+Business Media New York 1980

Authors and Affiliations

  • Kojiro Takahashi
    • 1
  • Carolyn S. Brown
    • 1
  • Henry Weiner
    • 1
  1. 1.Department of BiochemistryPurdue UniversityWest LafayetteUSA

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