s 5357 Biology 5357: s Assembly and Thermodynamics of Soft Matter Paul H. MD, PhD Department of Cell Biology and Physiology pschlesinger@.wustl.edu 362-2223
Characteristics s 5357 s are polymorphic
s 5357 Differential Scanning Calorimetry
s 5357 Analysis of a Temperature Transition The peak is a direct measure of the enthalpy of the transiton ( H cal ) At the midpoint, T m, the G = 0 so that S = H cal /T m (4)
s 5357 DPPC Thermal Transitions Equilibration of the sample Three transitons
s 5357 DPPC Thermal Transitions T m T 1/2 H cal S 18.4 3.0 3.23 11 35.1 1.8 1.09 3.5 41.1 0.18 6.9 11.0 Revisit the membrane structure for each phase.
s 5357 Pseudocrystalline L c Extended aliphatic chains with Φ angle and packing similar to that seen in available crystals of similar phsopholipids
s 5357 Gel L β Increased hydration of the headgroup (2 to 15), decreases packing in alkyl chains and some increase in cross sectional area
s 5357 Ripple P β At these temperatures long axis rotation dramatically increases but the tilt is retained producing the ripple
s 5357 Fluid L α This generates internal rotation in the alkane chains producing kinks that shorten the chains producing thinner and more spread membranes
Factors that influence phase behavior s 5357 Non-biological factors Degree of hydration Barotropic effects
s 5357 Vesicle size The curvature of vesicles affects the order of the chain packing and the interaction of the head groups.
s 5357 Alkane chain length Linear relationship with carbons in the alkane chains Indicates a co-operative threshold at 4 to 5 carbons Use of chain length to respond to environmental changes
s 5357 Alkane chain chemistry Linear, branched, cyclohexal substituted chains Mono-unsaturated Position of unsaturation (opt at 9-10) Position of unsaturated chain
Interdigitation s 5357 Structural, acyl asymmetry, sphingolipids Head group chain area asymmetry Interdigitation decreases void potential Consequence: Thickness, charge density, coupling loss of midplane
s 5357 Head group chemistry Size, polarity, charged groups Isolation of components for study Small, uncharged etc that let alkane chains dominate Charged groups ph, ionic strength Ion layers at the membrane surface
s 5357 Interfacial Chemistry Acyl to ether change reduce the Tm (phase destabilization) Amide groups, sphingolipids, increase T m (phase stabilization)
s 5357 Intrinsic. Add in the curvature and Helfrich
s 5357 curvature Add in the curvature and Helfrich
T Heimburg. Thermal Biophysics of s, chapter Introduction to Thermodynamics, pages 41 61. Wiley-VHC, Weinheim, 2007. K.E. van Holde, W.C. Johnson, and P.S. Ho. Principles of Physical Biochemistry, chapter Macromolecules in Solution: Thermodynamics and Equilibrium, pages 528 563. Prentice Hall, Upper Saddle River, New Jersey USA, 1998. s 5357 Add in the curvature and Helfrich S Blundell and K Blundell. Concepts in Thermal Physics, chapter 28. Phase. Oxford University Press, 2009.
Emiliano Brini, Christopher J. Fennell, Marivi Fernandez-Serra, Barbara Hribar-Lee, Miha Luksic, and Ken A. Dill. How water s properties are encoded in its molecular structure and energies. Chemical Reviews, 0(0):null, 0. PMID: 28949513. J. N. Israelachvili. Intermolecular and Surface, chapter Thermodynamic Principles of Self-Assembly, pages 503 534. Elsevier Inc., 2011. s 5357 Add in the curvature and Helfrich
D. G. Hall and B. A Pethica. Nonionic surfactants. Marcel Dekker, New York, 1967. New York: Dover Pubns. Hill, T. L. Benjamin. Thermodynamics of small systems. Dover Publications, 2002. Sarah L. Veatch, Olivier Soubias, Sarah L. Keller, and Klaus Gawrisch. Critical fluctuations in domain-forming lipid mixtures. Proceedings of the National Academy of Sciences, 104(45):17650 17655, November 2007. s 5357 Add in the curvature and Helfrich
T. Heimburg. Thermal Biophysics of s, chapter Phase Diagrams, pages 99 121. Wiley-VHC, Weinheim, 2007. Derek Marsh. Liquid-ordered phases induced by cholesterol: A compendium of binary phase diagrams. Biochimica et Biophysica Acta (BBA) - Biomembranes, January 2010. s 5357 Add in the curvature and Helfrich
Derek Marsh. Cholesterol-induced fluid membrane domains: a compendium of lipid-raft ternary phase diagrams. Biochimica et Biophysica Acta (BBA) - Biomembranes, 1788:2114 2123, August 2009. S. M. Gruner. The Structure of Biological s, chapter Nonlamellar s, pages 173 199. CRC Press, 2005. s 5357 Add in the curvature and Helfrich
R. N. A. H. Lewis and R. N. McElhaney. The Structure of Biological s, chapter The Mesomorphic Phase of Lipid Bilayers, pages 54 90. CRC Press, 2005. W. Helfrich. Elastic properties of lipid bilayers: theory and possible experiments. Z. Naturforsch., 28:693 703, 1973. s 5357 Add in the curvature and Helfrich
H. A. Pinnow and W. Helfrich. Effect of thermal undulations on the bending elasticity and spontaneous curvature of fluid membranes. The European Physical Journal E, 3(2):149 157, 2000. Michael F. Brown. Curvature forces in membrane Lipid-Protein interactions. Biochemistry, 51(49):9782 9795, December 2012. s 5357 Add in the curvature and Helfrich
S Blundell and K Blundell. Concepts in Thermal Physics, chapter 17. Rods Bubbles and Magnets, pages 191 202. Oxford University Press, 2009. P. H. and M. Saito. The bax pore in liposomes, biophysics. Cell Death and Differentiation, 13:1403 1408, 2006. s 5357 Add in the curvature and Helfrich