Kinetics of the coupled reaction catalysed by a fusion protein of yeast mitochondrial malate dehydrogenase and citrate synthase: Kinetics of a fusion protein of MDH and CS

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The mechanistic implications of the kinetic behaviour of a fusion protein of mitochondrial malate dehydrogenase and citrate synthase have been reanalysed in view of predictions based on experimentally determined kinetic parameter values for the dehydrogenase and synthase activities of the protein. The results show that the time-course of citrate formation from malate in the coupled reaction catalysed by the fusion protein can be most satisfactorily accounted for in terms of a free-diffusion mechanism when consideration is taken to the inhibitory effects of NADH and oxaloacetate on the malate dehydrogenase activity. The effect of aspartate aminotransferase on the coupled reaction is likewise fully consistent with that expected for a free-diffusion mechanism. It is concluded that no tenable kinetic evidence is available to support the proposal that the fusion protein catalyses citrate formation from malate by a mechanism involving channelling of the intermediate oxaloacetate.


Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Theoretical Chemistry
  • Biochemistry and Molecular Biology


  • fusion protein, channelling, malate dehydrogenase, Citrate (si)-Synthase, Oxaloacetic Acid, Recombinant Fusion Proteins, Saccharomyces cerevisiae, NAD, Models, Chemical, Mitochondria, Kinetics
Original languageEnglish
Pages (from-to)5041-5046
Number of pages6
JournalEuropean Journal of Biochemistry
Issue number16
Publication statusPublished - 2000
Publication categoryResearch