Properties and function of mitochondrial malate enzyme from bass liver.
Malate enzyme (L-malate: NADP+ oxidoreductase oxaloacetate decarboxylating, EC 1.1.1.40) from bass liver mitochondria was purified to over 90% of homogeneity by gel filtration, affinity and ion exchange chromatographies. The apparent molecular weight estimated by gel filtration was 316,000. Analysis of the enzyme on sodium dodecylsulphate-polyacrylamide disc gel electrophoresis was shown to be a tetramere protein. The enzyme required bivalent cations for catalysis, (Mn2+ or Mg2+) and displayed a narrow pH optimum (8.4-8.6 for Tris-HCl buffer) and was inactivated by p-chloromercuribenzoate. The double reciprocal initial velocity plots of both of the substrates, NADP and malate, were linear and intercepting at a point that suggests a sequential mechanism. Product inhibition studies with NADP and malate as variable substrate are consistent with an ordered Bi-Ter mechanism.
E
E
Madero
M
M
Gallego-Iniesta
A
A
Garrido-Pertierra
D000818:Animals; D005399:Fishes; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008291:Malate Dehydrogenase / Q000378:metabolism*; D008930:Mitochondria, Liver / Q000201:enzymology*; D008970:Molecular Weight
D008291:Malate Dehydrogenase