RGD Reference Report - Rat liver mitochondrial malate dehydrogenase: purification, kinetic properties, and role in ethanol metabolism. - Rat Genome Database

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Rat liver mitochondrial malate dehydrogenase: purification, kinetic properties, and role in ethanol metabolism.

Authors: Wiseman, MS  McKay, D  Crow, KE  Hardman, MJ 
Citation: Wiseman MS, etal., Arch Biochem Biophys. 1991 Oct;290(1):191-6.
RGD ID: 1582472
Pubmed: PMID:1898089   (View Abstract at PubMed)

Malate dehydrogenase was purified from the mitochondrial fraction of rat liver by ion-exchange chromatography with affinity elution. The kinetic parameters for the enzyme were determined at pH 7.4 and 37 degrees C, yielding the following values (microM): Ka, 72; Kia, 11; Kb, 110; Kp, 1600; Kip, 7100; Kq, 170; Kiq, 1100, where a = NADH, b = oxalacetate, p = malate, and q = NAD+. Kib was estimated to be about 100 microM. The maximum velocities for mitochondrial malate dehydrogenase in rat liver homogenates, at pH 7.4 and 37 degrees C, were 380 +/- 40 mumol/min per gram of liver, wet weight, for oxalacetate reduction and 39 +/- 3 mumol/min per gram of liver, wet weight, for malate oxidation. Rates of the reaction catalyzed by mitochondrial malate dehydrogenase under conditions similar to those in vivo were calculated using these kinetic parameters and were much lower than the maximum velocity of the enzyme. Since mitochondrial malate dehydrogenase is not saturated with malate at physiological concentrations, its kinetic parameters are probably important in the regulation of mitochondrial malate concentration during ethanol metabolism. For the mitochondrial enzyme to operate at a rate comparable to the flux through cytosolic malate dehydrogenase during ethanol metabolism (about 4 mumol min-1 per gram liver), the mitochondrial [malate] would need to be about 2 mM and the mitochondrial [oxalacetate] would need to be less than 1 microM.



Gene Ontology Annotations    Click to see Annotation Detail View

Biological Process

  
Object SymbolSpeciesTermQualifierEvidenceWithNotesSourceOriginal Reference(s)
Mdh2Ratmalate metabolic process  IDA  RGD 

Molecular Function

  
Object SymbolSpeciesTermQualifierEvidenceWithNotesSourceOriginal Reference(s)
Mdh2Ratmalate dehydrogenase activity  IDA  RGD 

Objects Annotated

Genes (Rattus norvegicus)
Mdh2  (malate dehydrogenase 2)


Additional Information