Biomaterial Database

Surface potential and the interaction of weakly acidic uncouplers of oxidative phosphorylation with liposomes and mitochondria. 1975

E P Bakker, and J C Arents, and J P Hoebe, and H Terada

The pH dependence of the binding of weakly acidic uncouplers of oxidative phosphorylation to rat-liver mitochondria and liposomes is mainly determined by the pKa of the uncoupler molecule. The absorption and fluorescene excitation spectra of the anionic form of weakly acidic uncouplers of oxidative phosphorylation are red-shifted upon interaction with liposomal or mitochondrial membranes. The affinity for the liposomes, as deduced from the red shift, is independent of the degree of saturation of the fatty acid chains of different lecithins. The intensity of the spectra at one pH value is strongly dependent upon the surface charge of the liposomes. With positively charged liposomes the results obtained can be almost quantitatively explained with the Gouy-Chapman theory, but with negatively charged ones deviations are observed. At a particular pH, the divalent ion Ca-2+ stongly influences the intensity of the spectra in the presence of negatively charged liposomes, but has no effect with neutral liposomes. With mitochondrial membranes an effect of Ca-2+ similar to that with negatively charged liposomes is observed. Depletion of the phospholipids of the mitochondria and subsequent restoration of the mitochrondrial membrane with lecithin, strongly diminishes this effect, but restoration with negatively charged phospholipids does not influence it. From these observations it is concluded that the anionic form of the uncoupler molecule when bound to mitochondria is located within the partly negatively charged phospholiped moiety of the membrane, with its anionic group pointing to the aqueous solution.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008081	Liposomes	Artificial, single or multilaminar vesicles (made from lecithins or other lipids) that are used for the delivery of a variety of biological molecules or molecular complexes to cells, for example, drug delivery and gene transfer. They are also used to study membranes and membrane proteins.	Niosomes,Transferosomes,Ultradeformable Liposomes,Liposomes, Ultra-deformable,Liposome,Liposome, Ultra-deformable,Liposome, Ultradeformable,Liposomes, Ultra deformable,Liposomes, Ultradeformable,Niosome,Transferosome,Ultra-deformable Liposome,Ultra-deformable Liposomes,Ultradeformable Liposome
D008274	Magnesium	A metallic element that has the atomic symbol Mg, atomic number 12, and atomic weight 24.31. It is important for the activity of many enzymes, especially those involved in OXIDATIVE PHOSPHORYLATION.
D008564	Membrane Potentials	The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).	Resting Potentials,Transmembrane Potentials,Delta Psi,Resting Membrane Potential,Transmembrane Electrical Potential Difference,Transmembrane Potential Difference,Difference, Transmembrane Potential,Differences, Transmembrane Potential,Membrane Potential,Membrane Potential, Resting,Membrane Potentials, Resting,Potential Difference, Transmembrane,Potential Differences, Transmembrane,Potential, Membrane,Potential, Resting,Potential, Transmembrane,Potentials, Membrane,Potentials, Resting,Potentials, Transmembrane,Resting Membrane Potentials,Resting Potential,Transmembrane Potential,Transmembrane Potential Differences
D008566	Membranes	Thin layers of tissue which cover parts of the body, separate adjacent cavities, or connect adjacent structures.	Membrane Tissue,Membrane,Membrane Tissues,Tissue, Membrane,Tissues, Membrane
D008930	Mitochondria, Liver	Mitochondria in hepatocytes. As in all mitochondria, there are an outer membrane and an inner membrane, together creating two separate mitochondrial compartments: the internal matrix space and a much narrower intermembrane space. In the liver mitochondrion, an estimated 67% of the total mitochondrial proteins is located in the matrix. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p343-4)	Liver Mitochondria,Liver Mitochondrion,Mitochondrion, Liver
D008931	Mitochondria, Muscle	Mitochondria of skeletal and smooth muscle. It does not include myocardial mitochondria for which MITOCHONDRIA, HEART is available.	Sarcosomes,Mitochondrion, Muscle,Muscle Mitochondria,Muscle Mitochondrion,Sarcosome
D009206	Myocardium	The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow.	Muscle, Cardiac,Muscle, Heart,Cardiac Muscle,Myocardia,Cardiac Muscles,Heart Muscle,Heart Muscles,Muscles, Cardiac,Muscles, Heart
D010085	Oxidative Phosphorylation	Electron transfer through the cytochrome system liberating free energy which is transformed into high-energy phosphate bonds.	Phosphorylation, Oxidative,Oxidative Phosphorylations,Phosphorylations, Oxidative
D010743	Phospholipids	Lipids containing one or more phosphate groups, particularly those derived from either glycerol (phosphoglycerides see GLYCEROPHOSPHOLIPIDS) or sphingosine (SPHINGOLIPIDS). They are polar lipids that are of great importance for the structure and function of cell membranes and are the most abundant of membrane lipids, although not stored in large amounts in the system.	Phosphatides,Phospholipid