Lipid polymorphism

CuUis, P.R., and de Kruiff, B., 1997, Lipid polymorphism and the functional roles oflipids in biological membranes, Biochim. Biophys. Acta 559 399-420. 

As stated, biological membranes are normally arranged as bilayers. It has, however, been observed that some lipid components of biological membranes spontaneously form non-lamellar phases, including the inverted hexagonal form (Figure 1.9) and cubic phases [101]. The tendency to form such non-lamellar phases is influenced by the type of phospholipid as well as by inserted proteins and peptides. An example of this is the formation of non-lamellar inverted phases by the polypeptide antibiotic Nisin in unsaturated phosphatidylethanolamines [102]. Non-lamellar inverted phase formation can affect the stability of membranes, pore formation, and fusion processes. So-called lipid polymorphism and protein-lipid interactions have been discussed in detail by Epand [103]. 

Luzzati, V., Gulik, A., Gulik-Krzywicki, T., Tardieu, A. Lipid polymorphism revisited Structural aspects and biological implications. Lipids and Membranes Past, Present, and Future. Elsevier, Amsterdam (1986), pp. 137-151. 

Erederik, R M., Burger, K. N., Stuart, M. C., and Verklej, A. J. (1991), Lipid polymorphism as observed by cryo-electron microscopy, Biochim.. Biophys. Acta, 1062,133-141. 

Epand RM. Lipid Polymorphism and Membrane Properties. 1997. Academic Press, San Diego, CA. 

Lewis RNAH, Mannock DA, McElhaney RN. Membrane Lipid 34. Molecular Structure and Polymorphism. In Lipid Polymorphism... 

Lipids constitute a diverse and important group of biomolecules. Most lipids can behave as lyotropic liquid crystals. In the presence of water, they self-assemble in a variety of phases with different stmcture and geometry. The lipid polymorphic and mesomorphic behavior, i.e., their ability to form various ordered, crystalline, gel, or liquid-crystalline phases as a function of water content, temperature, and composition, is one of the most intriguing features of lipid-water systems. The mutual transformations between these phases and their physiologic implications are the subject of this article. 

Lipid polymorphic and mesomorphic phases generally are characterized by their 1) symmetry in one, two, or three dimensions, 2) hydrocarbon chain ordering and specific chain arrangements in the ordered gel and crystalline phases, and 3) type (normal or inverted) for the curved mesomorphic phases. For four decades, the nomenclature introduced by Luzzati (40) has been used to designate lipid phases. Because of the rapid growth of the number of... 

Lewis RNAH, Mannock DA, McElhaney RN. Membrane lipid molecular structure and polymorphism. In Current Topics in Membranes, Volume 44. Lipid Polymorphism and Membrane Properties. Epand RM, ed. 1997. Academic Press, San Diego, pp. 25-102... 

Luzzati V. Biological significance of lipid polymorphism the cubic phases-commentary. Curr. Opin. Struct. Biol. 1997 7 661-668. 

Epand RM. Membrane lipid polymorphism relationship to bilayer... 

From a biological standpoint an essential property of lipid molecules is their ability to form aqueous phases, possessing long-range order combined with disorder at molecular distances. A variety of different phases exist for a particular lipid (polymorphism), and a small change in solution conditions is sufficient to cause a transformation from one form or structure to another. 

The same driving force behind lipid polymorphism in three dimensions -changes in the average molecular wedge-shape - can also operate in a membrane bilayer. It would be remarkable if polymorphism exhibited by lipid molecules is not utilised in membrane function. Further it must be expected that chemical changes of the lipid molecules that we know occur in membranes e.g. formation of diacylglycerol) are associated with bilayer conformational changes. 

Epand RM. Lipid polymorphism and protein-lipid interactions. Biochim Biophys Acta 1998 1376 353-368. Gawrisch K, Holte LL. NMR investigations of non-lamellar phase promoters in the lamellar phase state. 

Streicher-Scott J, Lapidus R, SokolovePM. Thereconstimtedmitochondrial adenine nucleotide translocator effects of lipid polymorphism. Arch Biochem Biophy 1994 315 548-554. 

De Kruijff B, Cullis P, Verkleij A, Hope MJ, Van Echteld CJA, Tataschi TF, Van Moogevast P, Killian JA, Rietveld A, Van Der Steen ATM Modulation of lipid polymorphism by lipid-... 

Control of texture and morphology of fat-based products by influencing neutral lipid polymorphism, i.e., the nature and size of triglyceride crystals... 

Figure 13.6 Schematic diagram of effect of temperature on nucleation rate of different lipid polymorphic forms. (From Hartel 1998b with permission.)...

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