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Selected Works

Thermodynamics

Prof. Stephanie Tristram-Nagle Ph.D.

Articles 1 - 5 of 5

Full-Text Articles in Physics

Thermodynamic And Structural Characterization Of Amino Acid-Linked Dialkyl Lipids., Stephanie Tristram-Nagle, Ruthven Lewis, Joseph Blickenstaff, Michael Diprima, Bruno Marques, Ronald Mcelhaney, John Nagle, James Schneider Aug 2014

Thermodynamic And Structural Characterization Of Amino Acid-Linked Dialkyl Lipids., Stephanie Tristram-Nagle, Ruthven Lewis, Joseph Blickenstaff, Michael Diprima, Bruno Marques, Ronald Mcelhaney, John Nagle, James Schneider

Prof. Stephanie Tristram-Nagle Ph.D.

Using differential scanning calorimetry (DSC), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR), we determined some thermodynamic and structural parameters for a series of amino acid-linked dialkyl lipids containing a glutamic acid-succinate headgroup and di-alkyl chains: C12, C14, C16 and C18 in CHES buffer, pH 10. Upon heating, DSC shows that the C12, C14 and annealed C16 lipids undergo a single transition which XRD shows is from a lamellar, chain ordered subgel phase to a fluid phase. This single transition splits into two transitions for C18, and FTIR shows that the upper main transition is predominantly the melting of ...


Hiv Fusion Peptide Penetrates, Disorders, And Softens T-Cell Membrane Mimics., Stephanie Tristram-Nagle, Rob Chan, Edgar Kooijman, Pradeep Uppamoochikkal, Wei Qiang, David Weliky, Pradeep Uppamoochikkal Aug 2014

Hiv Fusion Peptide Penetrates, Disorders, And Softens T-Cell Membrane Mimics., Stephanie Tristram-Nagle, Rob Chan, Edgar Kooijman, Pradeep Uppamoochikkal, Wei Qiang, David Weliky, Pradeep Uppamoochikkal

Prof. Stephanie Tristram-Nagle Ph.D.

This work investigates the interaction of N-terminal gp41 fusion peptide (FP) of human immunodeficiency virus type 1 (HIV-1) with model membranes in order to elucidate how FP leads to fusion of HIV and T-cell membranes. FP constructs were (i) wild-type FP23 (23 N-terminal amino acids of gp41), (ii) water-soluble monomeric FP that adds six lysines on the C-terminus of FP23 (FPwsm), and (iii) the C-terminus covalently linked trimeric version (FPtri) of FPwsm. Model membranes were (i) LM3 (a T-cell mimic), (ii) 1,2-dioleoyl-sn-glycero-3-phosphocholine, (iii) 1,2-dioleoyl-sn-glycero-3-phosphocholine/30 mol% cholesterol, (iv) 1,2-dierucoyl-sn-glycero-3-phosphocholine, and (v) 1,2-dierucoyl-sn-glycero-3-phosphocholine/30 mol% cholesterol. Diffuse ...


Lipid Bilayers: Thermodynamics, Structure, Fluctuations, And Interactions., Stephanie Tristram-Nagle, John Nagle Aug 2014

Lipid Bilayers: Thermodynamics, Structure, Fluctuations, And Interactions., Stephanie Tristram-Nagle, John Nagle

Prof. Stephanie Tristram-Nagle Ph.D.

This article, adapted from our acceptance speech of the Avanti Award in Lipids at the 47th Biophysical Society meeting in San Antonio, 2003, summarizes over 30 years of research in the area of lipid bilayers. Beginning with a theoretical model of the phase transition (J.F.N.), we have proceeded experimentally using dilatometry and density centrifugation to study volume, differential scanning calorimetry to study heat capacity, and X-ray scattering techniques to study structure of lipid bilayers as a function of temperature. Electron density profiles of the gel and ripple phases have been obtained as well as profiles from several fluid ...


Polymorphism In Myristoylpalmitoylphosphatidylcholine., Stephanie Tristram-Nagle, Yisrael Isaacson, Yulia Lyatskaya, Yufeng Liu, Kay Brummond, John Katsaras, John Nagle Aug 2014

Polymorphism In Myristoylpalmitoylphosphatidylcholine., Stephanie Tristram-Nagle, Yisrael Isaacson, Yulia Lyatskaya, Yufeng Liu, Kay Brummond, John Katsaras, John Nagle

Prof. Stephanie Tristram-Nagle Ph.D.

This study focuses on the mixed-chain lipid myristoylpalmitoylphosphatidylcholine (MPPC) near full hydration. The lipid, synthesized according to the procedure of (Mason et al., 1981a, has a low degree of acyl chain migration. When MPPC is temperature-jumped (T-jumped) from the L alpha phase (T = 38 degrees C) to T = 20 degrees C or below, a subgel phase forms; this formation takes less than 1 h at a temperature below T = 12 degrees C. The subgel remains stable up to T = 29 degrees C. When MPPC is T-jumped from the L alpha phase to T = 24 degrees C or above, a ripple ...


Polyunsaturated Docosahexaenoic Vs Docosapentaenoic Acid-Differences In Lipid Matrix Properties From The Loss Of One Double Bond., Nadukkudy Eldho, Scott Feller, Stephanie Tristram-Nagle, Ivan Polozov, Klaus Gawrisch Aug 2014

Polyunsaturated Docosahexaenoic Vs Docosapentaenoic Acid-Differences In Lipid Matrix Properties From The Loss Of One Double Bond., Nadukkudy Eldho, Scott Feller, Stephanie Tristram-Nagle, Ivan Polozov, Klaus Gawrisch

Prof. Stephanie Tristram-Nagle Ph.D.

Insufficient supply to the developing brain of docosahexaenoic acid (22:6n3, DHA), or its omega-3 fatty acid precursors, results in replacement of DHA with docosapentaenoic acid (22:5n6, DPA), an omega-6 fatty acid that is lacking a double bond near the chain's methyl end. We investigated membranes of 1-stearoyl(d(35))-2-docosahexaenoyl-sn-glycero-3-phosphocholine and 1-stearoyl(d(35))-2-docosapentaenoyl-sn-glycero-3-phosphocholine by solid-state NMR, X-ray diffraction, and molecular dynamics simulations to determine if the loss of this double bond alters membrane physical properties. The low order parameters of polyunsaturated chains and the NMR relaxation data indicate that both DHA and DPA undergo rapid ...