The evolution of membranes

Abstract

. J. Chem. 66, 706 (1988).Consideration of the influence of cholesterol on the physical properties of biological membranes leads to the conclusion that cholesterol increases the thickness of fluid membrane bilayers without appreciably increasing the microviscosity component of membrane fluidity. At sufficiently high cholesterol concentrations, the gel-liquid crystalline phase transition is completely eliminated in phospholipid-cholesterol mixtures and the system has the properties of a two-dimensional liquid over a wide range of temperatures. It is proposed that with the evolution of cholesterol and related sterols in an oxygen-rich atmosphere, the resulting modification of physical constraints on membrane properties made it possible for new evolutionary driving forces to manifest themselves leading to the peculiar properties of plasma membranes of eucaryotic cells.MYER BLOOM et OLE G. MOURITSEN. Can. J. Chem. 66, 706 (1988).Si on examine l'influence du cholestCro1 sur les propriCtCs physiques des membranes biologiques, on est amen6 B conclure que le cholesterol augmente 1'Cpaisseur des doubles couches des membranes fluides sans alfgmenter d'une facon appriciable la composante de la microviscosit6 de la fluidit6 de la membrane. A des concentrations de cholestCro1 suffisamment ClevCes, la transition de la phase cristalline gel-liquide est complktement CliminCe des mClanges phospholipide-cholestCro1 et, pour un grand intervalle de tempiratures, le systkme posskde les propriCtCs d'une liquide bi-dimensionnel. On est amen6 B proposer que, avec 1'Cvolution du cholestCro1 et des stCrols apparentCs dans un atmosphkre riche en oxygkne, la modification qui rCsulte de contraintes physiques sur les propriCtCs de la membrane fait qu'il est possible pour de nouvelles forces Cvolutionnaires de se manifester; ceci provoque l'apparition de propriitis particulikres pour les membranes plasmatiques des cellules eucaryotices.[Traduit par la revue]

Physical properties of the fluid lipid-bilayer component of cell membranes: a perspective

“…Or, are there subtle differences between the structural roles of these similarly shaped molecules associated with different types of molecules having been ' selected' by the evolutionary processes of the different types of cells ? Bloom & Mouritsen (1988) have proposed that the fact that sterols are found predominantly in the plasma membrane of eucaryotic cells is no accident and that sterols impart some important mechanical properties to these membranes. Recent developments on the structural role of cholesterol in membranes will be reviewed in Section 6.…”

“…Thus, S(n) is determined, to first approximation, by a very small number of parameters. A first indication of this is the experimental and theoretical evidence that the average acyl chain orientational order parameter {|>5 CD |) for saturated acyl chains in fluid membranes is linearly related to the hydrophobic thickness, d, of the membrane (Seelig & Seelig, 1980;Bloom & Mouritsen, 1988;Ipsen et al 1990a) as follows:…”

Cholesterol‐rich membrane coatings for interaction studies in capillary electrophoresis: Application to red blood cell lipid extracts

“…The maximum solubility of chol in PC bilayers is 66%, after which a separation of excess crystalline chol occurs [14,15]. Cholesterol serves as a mediator of membrane fluidity by breaking up gel domains that would otherwise make the membrane too rigid and by increasing the orientation of fluid membranes [16]. These properties are believed to be important in maintaining the biological activity of membranes.…”

Influence of cholesterol on dynamics of dimyristoylphosphatidylcholine bilayers as studied by deuterium NMR relaxation

“…1,2 Comparison of the 2 H nuclear magnetic resonance ͑NMR͒ relaxation rates of bilayers containing cholesterol to pure lipid bilayers can help investigate its role in membrane function and dynamics. [3][4][5][6][7][8][9][10] Cholesterol is a common component of biological membranes 11 and is implicated in cardiovascular diseases. 12 In addition, its inclusion into reconstituted phosphatidylcholine vesicles has been observed to alter the activity of the visual protein rhodopsin.…”