Collapsed bipolar glycolipids at the air/water interface: Effect of the stereochemistry on the stretched/bent conformations.

Alicia Jacquemet (1) , Nolwenn Terme (1) , Thierry Benvegnu (1) , Véronique Vié (2) , Loïc Lemiègre (1)

1 ISCR - Institut des Sciences Chimiques de Rennes
2 IPR - Institut de Physique de Rennes

This article describes a comparative study of several bipolar lipids derived from tetraether structures. The sole structural difference between the main two glycolipids is a unique stereochemical variation on a cyclopentyl ring placed in the middle of the lipids. We discuss the comparative results obtained at the air/water interface on the basis of tensiometry and ellipsometry. Langmuir-Blodgett depositions during lipid film compressions and decompressions were also analyzed by AFM. The lactosylated tetraether (bipolar) lipid structures involved the formation of highly stable multilayers, which are still present at 10mNm(-1) during decompression. This study suggests also that the stereochemistry of a central cyclopentyl ring dramatically drives the conformation of the corresponding bipolar lipids. Both isomers (trans and cis) adopt a U-shaped (bent) conformation at the air/water interface but the trans cyclopentyl ring induces a much more frustration within this type of conformation. Consequently, this bipolar lipid (trans-tetraether) undergoes a flip of one polar head-group (lactosyl) leading to a stretched conformation during collapse.

Mots clés: Bipolar lipid; Bolaamphiphile; Glycolipid; Cyclopentyl ring; Stereochemistry; Langmuir film; AFM

Domaines: Biophysique

Alicia Jacquemet, Nolwenn Terme, Thierry Benvegnu, Véronique Vié, Loïc Lemiègre. Collapsed bipolar glycolipids at the air/water interface: Effect of the stereochemistry on the stretched/bent conformations.. Journal of Colloid and Interface Science, 2013, 412, pp.72-81. ⟨10.1016/j.jcis.2013.09.010⟩. ⟨hal-00876528⟩