Related Experiment Video
Updated: Jul 15, 2026
22:00
Crystallizing Membrane Proteins for Structure Determination using Lipidic Mesophases
Published on: November 21, 2010
A new liquid crystalline phase in phosphatidylcholine bilayers as studied by X-ray diffraction
I Hatta1, S Matuoka, M A Singer
1Department of Applied Physics, Nagoya University, Japan.
Chemistry and Physics of Lipids
|February 1, 1994
Summary
Dilauroylphosphatidylcholine (C12PC) model membranes exhibit a novel liquid crystalline phase (Lx) between the gel and liquid crystalline phases. This Lx phase, confirmed by X-ray diffraction, offers insights into lipid bilayer behavior and may have biological relevance.
Area of Science:
- Lipid bilayer thermodynamics
- Phase transitions in model membranes
- Structural analysis of phospholipids
Background:
- Diacylphosphatidylcholines (CnPC) with saturated acyl chains typically show a single main phase transition.
- Dilauroylphosphatidylcholine (C12PC) exhibits an additional broad thermal event alongside its main transition.
- Previous calorimetric studies predicted a new phase (Lx) for C12PC bilayers between two thermal events.
Purpose of the Study:
- To confirm the existence of the predicted Lx phase in C12PC bilayers.
- To characterize the structural changes associated with the Lx phase.
- To elucidate the phase behavior of C12PC model membranes.
Main Methods:
- Synchrotron X-ray diffraction on C12PC model membranes.
- Differential scanning calorimetry (DSC) for thermal analysis.
- Analysis of small-angle (lamellar spacing) and wide-angle (hydrocarbon chain) diffraction data.
Main Results:
- Synchrotron X-ray diffraction confirmed the existence of the Lx phase.
- Abrupt discontinuities in lamellar and hydrocarbon chain spacings correlated with calorimetric peaks.
- A phase scheme of P beta' (gel ripple) -> Lx (new liquid crystalline) -> L alpha (disordered liquid crystalline) was established with increasing temperature.
Conclusions:
- The Lx phase in C12PC bilayers is structurally distinct and confirmed by X-ray diffraction.
- The Lx phase exists at a higher temperature than the main P beta' to L alpha transition.
- The Lx phase may be present in other CnPCs and is of potential biological significance due to its temperature range.
Related Concept Videos
02:18X-ray Crystallography
The size of the unit cell and the arrangement of atoms in a crystal may be determined from measurements of the diffraction of X-rays by the crystal, termed X-ray crystallography.
Diffraction
Diffraction is the change in the direction of travel experienced by an electromagnetic wave when it encounters a physical barrier whose dimensions are comparable to those of the wavelength of the light. X-rays are electromagnetic radiation with wavelengths about as long as the distance between neighboring...
Diffraction
Diffraction is the change in the direction of travel experienced by an electromagnetic wave when it encounters a physical barrier whose dimensions are comparable to those of the wavelength of the light. X-rays are electromagnetic radiation with wavelengths about as long as the distance between neighboring...
01:35Asymmetric Lipid Bilayer
Biological membranes show uneven distribution of different types of lipids in the inner and outer layers, resulting in transverse asymmetric membranes. The treatment of the erythrocyte membrane with the enzyme phospholipase confirmed the asymmetric nature of the lipid bilayer. The enzyme hydrolyzes lipids into fatty acids and hydrophilic groups. The phospholipase acts only on the outer layer of the membrane, while the inner layer remains intact. The phospholipase treatment resulted in 80%...
01:27Synthesis of Phosphatidylcholine in the ER Membrane
The ER synthesizes lipids for building cell membranes and performing cellular functions such as energy storage and signaling. The lipid synthesis machinery embedded in the ER membrane primarily collects all reactants from the cytosol. Following synthesis, the secretory pathway and the ER contact sites distribute these lipids to other cellular organelles. Additionally, the energy-rich triacylglycerides are transported from the ER via lipid droplets.
The major components of all eukaryotic cell...
The major components of all eukaryotic cell...
01:10X-ray Diffraction of Biological Samples
X-ray diffraction or XRD is an analytical tool that utilizes X-rays to study ordered structures such as crystalline organic and inorganic samples, polycrystalline materials, proteins, carbohydrates, and drugs.
According to Bragg's law, when X-rays strike the sample positioned on a stage, the rays are scattered by the electron clouds around the sample atoms. The X-ray diffraction or scattering is caused by constructive interference of the X-ray waves that reflect off the internal crystal...
According to Bragg's law, when X-rays strike the sample positioned on a stage, the rays are scattered by the electron clouds around the sample atoms. The X-ray diffraction or scattering is caused by constructive interference of the X-ray waves that reflect off the internal crystal...
01:29Determination of Crystal Structures
In the late 1800s, the revelation that light extended beyond visible wavelengths led to the discovery of X-rays by Wilhelm Roentgen. Recognized as high-energy electromagnetic radiation with short wavelengths, X-rays prompted exploration into their interaction with crystals. Max von Laue proposed in 1912 that the periodic arrangement of atoms, ions, or molecules in crystals would cause them to diffract X-rays, a hypothesis confirmed through experiments with copper sulfate and zinc sulfide...