Measurement of Kinetics and Mechanisms of Phase Transitions in Lipid–Water Systems

Quinn, Peter J.

doi:10.1107/s0021889897001155

Cited by 7 publications

(3 citation statements)

References 35 publications

(39 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The combination of a quadrant detector to measure small‐angle X‐ray scattering (SAXS) intensity and an INEL curved linear‐wire detector (Instrumentation Electronique, France) to measure wide‐angle X‐ray scattering (WAXS) was used. Details of the station set‐up have been published elsewhere [19]. Samples were mounted in a slot (1 × 5 mm) cut in a 1‐mm thick copper plate sandwiched between a pair of thin mica sheets.…”

Section: Methodsmentioning

confidence: 99%

The effect of α‐tocopherol on the thermotropic phase behaviour of dipalmitoylphosphatidylethanolamine

Wang

Quinn

1999

European Journal of Biochemistry

View full text Add to dashboard Cite

The effect of a-tocopherol on the thermotropic phase behaviour of aqueous dispersions of dipalmitoylphosphatidylethanolamine in mixtures containing 0, 2.5, 5, 10 and 20 mol% a-tocopherol was examined using synchrotron X-ray diffraction methods. Dispersions were equilibrated for at least 12 h at 4 8C before measurement. The phospholipid alone undergoes a lamellar gel to liquid-crystalline phase transition at 66 8C during the initial heating scan. When codispersed with a-tocopherol there was evidence of phase separation of a-tocopherol-rich domains from bilayers of pure phospholipid. The a-tocopherol-rich domains were identified from the relationship between scattering intensity of the phase and the proportion of a-tocopherol in the mixture. In initial heating scans a-tocopherol-rich domains were characterized by broad lamellar repeat spacings (5.0 nm at 55 8C) in the small-angle scattering region which first appears at <40 8C and increases in intensity with increasing temperature. In the presence of more than 5 mol% a-tocopherol the wide-angle scattering region showed two scattering profiles consisting of multiple peaks typical of lamellar crystal phases. The lowtemperature crystal phase, designated Lc 1 , was transformed into Lc 2 phase at <50 8C. On further heating the Lc 2 phase was transformed directly into inverted hexagonal phase at <56 8C and coexisted with the lamellar gel phase of the pure phospholipid. The inverted hexagonal phase coexists with the lamellar phase of the pure phospholipid, after transformation into lamellar liquid-crystal phase at 66 8C, at least up to 70 8C. In cooling scans the d-spacing of the inverted hexagonal phase decreases progressively and the scattering intensity weakens on cooling below the liquid-crystal to gel phase transition temperature of the pure phospholipid. There is no evidence of formation of lamellar crystal phases during cooling so that the a-tocopherol either mixes with the lamellar gel phase of the phospholipid without change in the structural parameters of the pure phospholipid or is completely phase separated from the phospholipid. The stoichiometry of phospholipid/a-tocopherol in the a-tocopherol-rich lamellar crystal and inverted hexagonal phases is estimated to be <4 : 1. The structural changes observed in the study are related to the calorimetric transitions reported in independent work on these dispersions.Keywords: phase transition; phospholipid; a-tocopherol; vitamin E; X-ray diffraction.a-Tocopherol is a ubiquitous lipid component of biological membranes. It is believed to have two primary functions in cells: a major role is thought to be as an antioxidant acting to prevent free radical damage to tissues [1±5] and a subsidiary function is to stabilize the structure of membranes [6]. In order to understand the biological functions of a-tocopherol at the molecular level, it is essential to understand the interaction between a-tocopherol and phospholipids that represent the major components of the membrane lipid bilayer matrix.The effect of a-tocopherol on...

show abstract

Section: Methodsmentioning

confidence: 99%

The effect of α‐tocopherol on the thermotropic phase behaviour of dipalmitoylphosphatidylethanolamine

Wang

Quinn

1999

European Journal of Biochemistry

View full text Add to dashboard Cite

show abstract

“…Caffrey and Cheng, 1995;Quinn, 1997;Cherezov et al, 2003 and references therein]. In most cases these papers applied temperature or pressure jumps to try to find the maximum transition speed, and used this to study the mechanisms of the transition.…”

Section: Figurementioning

confidence: 98%

Kinetics of the lamellar gel–fluid transition in phosphatidylcholine membranes in the presence of sugars

Lenné

Garvey

Koster

et al. 2010

Chemistry and Physics of Lipids

View full text Add to dashboard Cite

Phase diagrams are presented for dipalmitoylphosphatidylcholine (DPPC) in the presence of sugars (sucrose) over a wide range of relative humidities (RHs). The phase information presented here, determined by small angle X-ray scattering (SAXS), is shown to be consistent with previous results achieved by differential scanning calorimetry (DSC). Both techniques show a significant effect of sucrose concentration on the phase behaviour of this phospholipid bilayer. An experimental investigation into the effect of sugars on the kinetic behaviour of the gel to fluid transition is also presented showing that increasing the sugar content appears to slightly increase the rate at which the transition occurs.

show abstract

“…Here, c l and c 2 , are principal curvatures which are the inverses of the principal radii of curvature R 1 and R 2 [7b] The surface averaged values of mean curvature 92 and Gaussian curvature 93 The parameters tabulated above form the basis of understanding the general behavior of the phases observed for general amphiphiles. However, behavioral details under various conditions are studied and reviewed elsewhere, which include swelling behavior 31,40,71,[97][98][99][100][101][102][103][104][105][106] and neutral surface calculations, 31,76,[107][108][109][110][111] kinetics of phase transitions, 55,59,88,102,[112][113][114][115][116][117][118][119][120][121][122][123][124] thermodynamic and energetic calculations 27,31,115,[125][126][127]…”

mentioning

confidence: 99%

Monoolein: a magic lipid?

Kulkarni

Wachter

Iglesias

et al. 2011

Phys. Chem. Chem. Phys.

393

403

View full text Add to dashboard Cite

During the last few years, there has been an extraordinary increase in publications describing the manifold applications of monoolein, one of the most important lipids in the fields of drug delivery, emulsion stabilization and protein crystallization. In this perspective we present a comprehensive review of the phase behavior of this 'magic lipid'. An account of various mesophases formed in the presence of water and a collection of formulae for the calculation of their nano-structural parameters are provided. Effects of chemical and biological molecules including lipids, detergents, salts, sugars, proteins and DNA on the classical behavior are also discussed. Physicochemical triggers such as, temperature, pressure and shearing modulate the phase behavior of monoolein self assemblies that are covered in subsequent sections. Finally the growing applications of monoolein in various fields are also reported.

show abstract

Measurement of Kinetics and Mechanisms of Phase Transitions in Lipid–Water Systems

Cited by 7 publications

References 35 publications

The effect of α‐tocopherol on the thermotropic phase behaviour of dipalmitoylphosphatidylethanolamine

The effect of α‐tocopherol on the thermotropic phase behaviour of dipalmitoylphosphatidylethanolamine

Kinetics of the lamellar gel–fluid transition in phosphatidylcholine membranes in the presence of sugars

Monoolein: a magic lipid?

Contact Info

Product

Resources

About