Hydrophobic interaction between the monomer of mitochondrial malate dehydrogenase and phospholipid membranes.
Porcine mitochondrial malate dehydrogenase (EC 1.1.1.37) dissociates into subunits on dilution. The enzyme monomer caused large increases in the surface pressure of monolayers of 1:1 phosphatidylserine/phosphatidylcholine at air/water and oil/water interfaces. The monomer increased the permeability of phospholipid vesicles to 22Na+. Both effects were significantly greater than the corresponding effects of ribonuclease A, cytochrome c and the dimeric form of malate dehydrogenase. Changes in the circular-dichroism spectra of the enzyme indicated that conformational changes may be associated with dimer formation or when monomer interacts with lysophosphatidyl-choline. Similar interactions to those described may occur in situ when mitochondrial malate dehydrogenase is transported to the mitochondrial matrix from its site of synthesis on cytosolic ribosomes.
D000818:Animals; D002463:Cell Membrane Permeability; D002942:Circular Dichroism; D007425:Intracellular Membranes / Q000378:metabolism; D046911:Macromolecular Substances; D008291:Malate Dehydrogenase / Q000378:metabolism*; D008563:Membrane Lipids / Q000378:metabolism*; D008928:Mitochondria / Q000201:enzymology*; D010743:Phospholipids / Q000378:metabolism*; D011487:Protein Conformation; D013500:Surface Tension; D013552:Swine
D046911:Macromolecular Substances; D008563:Membrane Lipids; D010743:Phospholipids; D008291:Malate Dehydrogenase