title: Hydrophobic interaction between the monomer of mitochondrial malate dehydrogenase and phospholipid membranes.
abstract: 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.
mesh_terms: 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
chemical_list: D046911:Macromolecular Substances; D008563:Membrane Lipids; D010743:Phospholipids; D008291:Malate Dehydrogenase