Hydrocarbon chain trans-gauche isomerization in phospholipid bilayer gel assemblies

: The vibrational Raman spectra of dimyristoyl (DMPC)-, dipalmitoyl (DPPC)-, and distearoylphosphatidycholine (DSPC)-water bilayer system were used to probe lipid hydrocarbon chain trans-gauch isomerization dynamics below the gel-liquid crystalline phase transition temperature. In addition to the 1090-1085 cm-1 vibrational transitions, which appear with increasing temperatures and are characteristic of gauche conformers within the acyl chains, a new feature arises in all three bilayer systems at approximately 1122 cm-1. This carbon-carbon stretching mode is associated with the formation of the gauche bond rotation of the terminal methyl group oriented toward the center of the bilayer. Estimates of the enthalpy differences (deltaH) between hydrocarbon chains in an all-trans conformation and chain configurations containing gauche forms may be made from peak height intensities of vibrational features associated with the appropriate rotational isomers. For the DMPC-H2O, DPPC-H2O, and DSPC-H2O assemblies, the Raman data yield enthalpy differences of 2.9 +/- 0.6, 3.4 +/- 0.5, and 9.9 +/- 1.2 kcal/mol, respectively. These values are interpreted to reflect approximately two gauche bonds per lipid molecule for the DMPC-H2O and the DPPC-H2O gels and six gauche bonds per molecule for the DSPC-H2O gels.

[1]  M. B. Jackson.  A beta-coupled gauche kink description of the lipid bilayer phase transition. , 1976, Biochemistry.

[2]  J. Mccammon,et al.  "Semiempirical" models for biomembrane phase transitions and phase separations. , 1975, Journal of the American Chemical Society.

[3]  H. C. Andersen,et al.  A theory of the chain melting phase transition of aqueous phospholipid dispersions. , 1975, Proceedings of the National Academy of Sciences of the United States of America.

[4]  I W Levin,et al.  Raman spectra and vibrational assignments for dipalmitoyl phosphatidylcholine and structurally related molecules. , 1975, Biochimica et biophysica acta.

[5]  J. Seelig,et al.  Deuterium order parameters in relation to thermodynamic properties of a phospholiped bilayer. A statistical mechanical interpretation. , 1975, Biochemistry.

[6]  A G Lee,et al.  Functional properties of biological membranes: a physical-chemical approach. , 1975, Progress in biophysics and molecular biology.

[7]  William F. Murphy,et al.  Rotational isomerism. XI. Raman spectra of n-butane, 2-methylbutane, and 2, 3-dimethylbutane , 1974 .

[8]  J. Nagle.  Theory of biomembrane phase transitions , 1973 .

[9]  J. Rothman.  The molecular basis of mesomorphic phase transitions in phospholipid systems. , 1973, Journal of theoretical biology.

[10]  J. Sturtevant,et al.  Calorimetric studies of dilute aqueous suspensions of bilayers formed from synthetic L- -lecithins. , 1972, The Journal of biological chemistry.

[11]  J. L. Lippert,et al.  Raman active vibrations in long-chain fatty acids and phospholipid sonicates. , 1972, Biochimica et biophysica acta.

[12]  Y. K. Levine.  Physical studies of membrane structure. , 1972, Progress in biophysics and molecular biology.

[13]  H. Träuble.  Phase transitions in lipids. , 1972, Biomembranes.

[14]  J. Seelig.  On the flexibility of hydrocarbon chains in lipid bilayers. , 1971, Journal of the American Chemical Society.

[15]  J. L. Lippert,et al.  Laser Raman investigation of the effect of cholesterol on conformational changes in dipalmitoyl lecithin multilayers. , 1971, Proceedings of the National Academy of Sciences of the United States of America.

[16]  I. W. Levin.  A low temperature Raman cell: solid spectra of the v1 vibrations of the group IV tetrachlorides , 1969 .

[17]  R. F. Schaufele.  Chain Shortening in Polymethylene Liquids , 1968 .

[18]  R. G. Snyder.  Vibrational Study of the Chain Conformation of the Liquid n‐Paraffins and Molten Polyethylene , 1967 .

[19]  H. Bernstein.  Internal Rotation II The Energy Difference between the Rotational Isomers of 1,2‐Dichloroethane , 1949 .