Impact of Structural Differences in Galactocerebrosides on the Behavior of 2D Monolayers

Abstract

The molecular interactions of three biologically important galactocerebrosides have been studied in monolayers formed at the soft air/water interface as 2D model membranes. Highly surface-sensitive techniques as GIXD (grazing incidence X-ray diffraction), IRRAS (infrared reflection-absorption spectroscopy), and BAM (Brewster angle microscopy) have been used. The study reveals that small differences in the chemical structure have a relevant impact on the physical-chemical properties and intermolecular interactions. The presence of a 2-d-hydroxyl group in the fatty acid favored for GalCer C24:0 (2-OH) monolayers a higher hydration state of the headgroup at low lateral pressures (<25 mN/m) and a higher condensation effect above 30 mN/m. An opposite behavior was recorded for GalCer C24:0 and GalCer C24:1, for which the intermolecular interactions are defined by the weakly hydrated but strong H-bonded interconnected head groups. Additionally, the 15-cis-double bond in the fatty acid chain (nervonic acid) of GalCer C24:1 stabilized the LE phase but did not disturb the packing parameters of the LC phase as compared with the saturated compound GalCer C24:0.

Synthesis of Gb3 Glycosphingolipids with Labeled Head Groups: Distribution in Phase‐Separated Giant Unilamellar Vesicles

“…Ther esults ( Figure 5) clearly indicate that the OH group in the a-position does not influence its distribution. Thed ifferences of %l o for 1/3 and 5/7 are in the range of À0.03-0.03 and are not significant ( Monolayer experiments on galactosyl ceramide (GalCer), harboring either an a-hydroxylated or nonhydroxylated C 24:0 fatty acid on aL angmuir trough, suggest that the ahydroxylation does not change the area per lipid at 30 mN m À1 , [44] as urface pressure that reflects the packing density of bilayers. [45] Using 2 HNMR spectroscopy,M orrow and co-workers [41,46] also demonstrated that the order parameter of the fatty acids of GalCer embedded in aP OPC/Chol membrane and the orientation of the head group does not change considerably.…”

Synthesis of Gb3 Glycosphingolipids with Labeled Head Groups: Distribution in Phase‐Separated Giant Unilamellar Vesicles

“…Monolayer experiments on galactosyl ceramide (GalCer), harboring either an α‐hydroxylated or nonhydroxylated C 24:0 fatty acid on a Langmuir trough, suggest that the α‐hydroxylation does not change the area per lipid at 30 mN m −1 , a surface pressure that reflects the packing density of bilayers . Using 2 H NMR spectroscopy, Morrow and co‐workers also demonstrated that the order parameter of the fatty acids of GalCer embedded in a POPC/Chol membrane and the orientation of the head group does not change considerably.…”

Interaction between 17 α-ethynylestradiol hormone with Langmuir monolayers: The role of charged headgroups

“…EE2 causes all the monolayers to have a reduced C −1 s ; the monolayers become more compressible with incorporation of EE2, especially for the charged DODAB and DPPG. At 30 mN.m −1 , which is the pressure believed to correspond to a real cell mem- brane [27,28], C −1 s decreased by 60% for DODAB, 57% for DPPG, 13% for DPPC, and 12% for StAc (from Fig. SI-2).…”