Abstract
Unsaturated phospholipid is the membrane component that is essential to the dynamic environment needed for biomembrane function. The dependence of the chain-melting transition temperature, T(t), of phospholipid bilayer membranes on the position, n(u), of the cis double bond in the glycerophospholipid sn-2 chain can be described by an expression of the form T(t) = T(t)(c)(1 + h'(c)|n(u) - n(c)|)/(1 + s'(c)|n(u) - n(c)|), where n(c) is the chain position of the double bond corresponding to the minimum transition temperature, T(t)(c), for constant diacyl lipid chain lengths. This implies that the incremental transition enthalpy (and entropy) contributed by the sn-2 chain is greater for whichever of the chain segments, above or below the double-bond position, is the longer. The critical position, n(c), of the double bond is offset from the center of the sn-2 chain by an approximately constant amount, deltan(c) approximately 1. 5 C-atom units. The dependence of the parameters T(t)(c), h'(c), and s'(c) on sn-1 and sn-2 chain lengths can be interpreted consistently when allowance is made for the chain packing mismatch between the sn-1 and sn-2 chains. The length of the sn-2 chain is reduced by approximately 0.8 C-atom units by the cis double bond, in addition to a shortening by approximately 1.3 C-atom units by the bent configuration at the C-2 position. Based on this analysis, a general thermodynamic expression is proposed for the dependence of the chain-melting transition temperature on the position of the cis double bond and on the sn-1 and sn-2 chain lengths. The above treatment is restricted mostly to double-bond positions close to the center of the sn-2 chain. For double bonds positioned closer to the carboxyl or terminal methyl ends of the sn-2 chain, the effects on transition enthalpy can be considerably larger. They may be interpreted by the same formalism, but with different characteristic parameters, h'(c) and s'(c), such that the shorter of the chain segments makes a considerably smaller contribution to the calorimetric properties of the chain-melting transition.
Full Text
The Full Text of this article is available as a PDF (141.4 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Barton P. G., Gunstone F. D. Hydrocarbon chain packing and molecular motion in phospholipid bilayers formed from unsaturated lecithins. Synthesis and properties of sixteen positional isomers of 1,2-dioctadecenoyl-sn-glycero-3-phosphorylcholine. J Biol Chem. 1975 Jun 25;250(12):4470–4476. [PubMed] [Google Scholar]
- Cevc G. How membrane chain-melting phase-transition temperature is affected by the lipid chain asymmetry and degree of unsaturation: an effective chain-length model. Biochemistry. 1991 Jul 23;30(29):7186–7193. doi: 10.1021/bi00243a021. [DOI] [PubMed] [Google Scholar]
- Dekker C. J., Geurts van Kessel W. S., Klomp J. P., Pieters J., De Kruijff B. Synthesis and polymorphic phase behaviour of polyunsaturated phosphatidylcholines and phosphatidylethanolamines. Chem Phys Lipids. 1983 Jul;33(1):93–106. doi: 10.1016/0009-3084(83)90012-9. [DOI] [PubMed] [Google Scholar]
- Huang C. H., Li S., Lin H. N., Wang G. On the bilayer phase transition temperatures for monoenoic phosphatidylcholines and phosphatidylethanolamines and the interconversion between them. Arch Biochem Biophys. 1996 Oct 1;334(1):135–142. doi: 10.1006/abbi.1996.0438. [DOI] [PubMed] [Google Scholar]
- Huang C. Mixed-chain phospholipids and interdigitated bilayer systems. Klin Wochenschr. 1990 Feb 1;68(3):149–165. doi: 10.1007/BF01649079. [DOI] [PubMed] [Google Scholar]
- Lewis R. N., Sykes B. D., McElhaney R. N. Thermotropic phase behavior of model membranes composed of phosphatidylcholines containing cis-monounsaturated acyl chain homologues of oleic acid: differential scanning calorimetric and 31P NMR spectroscopic studies. Biochemistry. 1988 Feb 9;27(3):880–887. doi: 10.1021/bi00403a007. [DOI] [PubMed] [Google Scholar]
- Li S., Lin H. N., Wang Z. Q., Huang C. Identification and characterization of kink motifs in 1-palmitoyl-2-oleoyl- phosphatidylcholines: a molecular mechanics study. Biophys J. 1994 Jun;66(6):2005–2018. doi: 10.1016/S0006-3495(94)80993-2. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Li S., Wang G., Lin H., Huang C. H. Calorimetric studies of phosphatidylethanolamines with saturated sn-1 and dienoic sn-2 Acyl chains. J Biol Chem. 1998 Jul 24;273(30):19009–19018. doi: 10.1074/jbc.273.30.19009. [DOI] [PubMed] [Google Scholar]
- Marsh D. Analysis of the bilayer phase transition temperatures of phosphatidylcholines with mixed chains. Biophys J. 1992 Apr;61(4):1036–1040. doi: 10.1016/S0006-3495(92)81911-2. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Marsh D. Analysis of the chainlength dependence of lipid phase transition temperatures: main and pretransitions of phosphatidylcholines; main and non-lamellar transitions of phosphatidylethanolamines. Biochim Biophys Acta. 1991 Feb 11;1062(1):1–6. doi: 10.1016/0005-2736(91)90326-4. [DOI] [PubMed] [Google Scholar]
- Seddon J. M., Cevc G., Marsh D. Calorimetric studies of the gel-fluid (L beta-L alpha) and lamellar-inverted hexagonal (L alpha-HII) phase transitions in dialkyl- and diacylphosphatidylethanolamines. Biochemistry. 1983 Mar 1;22(5):1280–1289. doi: 10.1021/bi00274a045. [DOI] [PubMed] [Google Scholar]
- Wang G., Lin H. N., Li S., Huang C. H. Phosphatidylcholines with sn-1 saturated and sn-2 cis-monounsaturated acyl chains. Their melting behavior and structures. J Biol Chem. 1995 Sep 29;270(39):22738–22746. [PubMed] [Google Scholar]
- Wang Z. Q., Lin H. N., Li S., Huang C. H. Calorimetric studies and molecular mechanics simulations of monounsaturated phosphatidylethanolamine bilayers. J Biol Chem. 1994 Sep 23;269(38):23491–23499. [PubMed] [Google Scholar]
- Wang Z. Q., Lin H. N., Li S., Huang C. H. Phase transition behavior and molecular structures of monounsaturated phosphatidylcholines. Calorimetric studies and molecular mechanics simulations. J Biol Chem. 1995 Feb 3;270(5):2014–2023. doi: 10.1074/jbc.270.5.2014. [DOI] [PubMed] [Google Scholar]