Related Experiment Video
Updated: May 22, 2026

Combining X-Ray Crystallography with Small Angle X-Ray Scattering to Model Unstructured Regions of Nsa1 from S. Cerevisiae
Published on: January 10, 2018
Stereochemical effect revealed in self-assemblies based on archaeal lipid analogues bearing a central five-membered
Alicia Jacquemet1, Cristelle Mériadec, Loïc Lemiègre
1Ecole Nationale Supérieure de Chimie de Rennes, CNRS, UMR 6226, Avenue du Général Leclerc, CS 50837, 35708 Rennes Cedex 7, France.
Abstract:
The relative stereochemistry (cis or trans) of a 1,3-disubstituted cyclopentane unit in the middle of tetraether archaeal bipolar lipid analogues was found to have a dramatic influence on their supramolecular self-assembly properties. SAXS studies of two synthetic diastereomeric archaeal lipids bearing two lactosyl polar head groups at opposite ends revealed different lyotropic behaviors. The cis isomer led to L(c)-L(α)-Q(II) transitions whereas the trans isomer retained an L(α) phase from 20 to 100 °C. These main differences originate from the conformational equilibrium (pseudorotation) of 1,3-disubstituted cyclopentanes. Indeed, this pseudorotation exhibits quite similar orientations of the two substituents in a trans isomer whereas several orientations of the two alkyl chains are expected in a cis-1,3-dialkyl cyclopentane, thus authorizing more conformational flexibility in the lipid packing.
Related Concept Videos
Biosynthesis of Lipids
Stereoisomerism of Cyclic Compounds
Diels–Alder Reaction Forming Cyclic Products: Stereochemistry
Diels–Alder Reaction Forming Bridged Bicyclic Products: Stereochemistry
SN2 Reaction: Stereochemistry
If the substrate is an achiral molecule at the α-carbon, the inversion of configuration is not observed.
Assembly of the Lipid Bilayer in the ER
A large chunk of any biological membrane is composed of phospholipids. These lipids have a heterogeneous distribution across different subcellular organelles and even between...

