Monolayers cardiolipin

Cardiolipin Monolayers. Among various phospholipids studied by monolayer techniques, only cardiolipin (41) and phosphatidylserine (36) monolayers show significant condensation of their surface pressure-area curves in the presence of divalent as compared with monovalent cations in the subsolution. The condensation of cardiolipin is explained by the decrease in molecular area caused by the attraction between a divalent cation and the two phosphate groups in the molecule. This condensation is eliminated when the ratio of monovalent to divalent cations is greater than 5 to 1. At high surface pressures, the difference in the compressibility of cardiolipin monolayers correlates with the ionic radii of the metal ions (Mg2+ < Ca2+ < Sr2+ < Ba2+). 

Fig. 13a In-plane diffraction intensity for a cardiolipin monolayer on water without and with PDADMAC in the subphase...

Interactions of cytochrome c and [14C] carboxymethylated cytochrome c with monolayers of phophatidylcholine, phosphatidic acid and cardiolipin, Quinn, P.J. Dawson, R.M.C. Biochem J. 1969, 115,6 5. 

In the plasma membrane of animals (1), the amount of cholesterol is usually around 20-30 mol%. The rest of the lipids are mainly PC, PE, and sphingomyelin (SM) lipids, with smaller amounts of PS, PI, and glycolipids. These lipids are distributed asymmetrically across the membrane, because most cholesterol, PC, and glycolipids are located in the extracellular (outer) leaflet, whereas PS and PE lipids are located mainly in the intracellular (inner) monolayer. The lipid composition can be highly different in other organelles, however, as is the case in mitochondria (1), in which the mitochondrial membrane is composed of two (inner and outer) membranes. There, the amounts of cholesterol, SM, and PS are negligible most lipids are PC and PE. The major difference compared with plasma membrane is the concentration of cardiolipins. They are actually found only in bacterial and in mitochondrial membranes, where their numbers are significant even in mitochondria they are located mainly on the iimer membrane. 

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