Interaction of Hexadecylbetainate Chloride with Biological Relevant Lipids

Abstract

The present work investigates the interaction of hexadecylbetainate chloride (C(16)BC), a glycine betaine-based ester with palmitoyl-oleoyl-phosphatidylcholine (POPC), sphingomyelin (SM), and cholesterol (CHOL), three biological relevant lipids present in the outer leaflet of the mammalian plasma membrane. The binding affinity and the mixing behavior between the lipids and C(16)BC are discussed based on experimental (isothermal titration calorimetry (ITC) and Langmuir film balance) and molecular modeling studies. The results show that the interaction between C(16)BC and each lipid is thermodynamically favorable and does not affect the integrity of the lipid vesicles. The primary adsorption of C(16)BC into the lipid film is mainly governed by a hydrophobic effect. Once C(16)BC is inserted in the lipid film, the polar component of the interaction energy between C(16)BC and the lipid becomes predominant. Presence of CHOL increases the affinity of C(16)BC for membrane. This result can be explained by the optimal matching between C(16)BC and CHOL within the film rather by a change of membrane fluidity due to the presence of CHOL. The interaction between C(16)BC and SM is also favorable and gives rise to highly stable monolayers probably due to hydrogen bonds between their hydrophilic groups. The interaction of C(16)BC with POPC is less favorable but does not destabilize the mixed monolayer from a thermodynamic point of view. Interestingly, for all the monolayers investigated, the exclusion surface pressures are above the presumed lateral pressure of the plasma membranes suggesting that C(16)BC would be able to penetrate into mammalian plasma membranes in vivo. These results may serve as a useful basis in understanding the interaction of C(16)BC with real membranes.

Development of coated liposomes loaded with ghrelin for nose-to-brain delivery for the treatment of cachexia

“…27 All measurements were performed at 25°C using a MicroCal VP-ITC (Malvern Instruments) with a sample cell volume of 1.4565 mL. Solutions were degassed in a sonic bath for 10 minutes prior to use.…”

“…Raw ITC data were processed according to the cumulative model previously described 28 and applied to molecules other than Ghrl 27,29 to obtain the thermodynamic parameters characteristic of the interaction of Ghrl-AL-free. Thermodynamic parameters considered were binding coefficient (K), variation in Gibbs free energy (ΔG), enthalpy (ΔH), and entropy (TΔS).…”

Linoleic and linolenic acid hydroperoxides interact differentially with biomimetic plant membranes in a lipid specific manner

“…ITC experiments were performed as described previously [16]. All measurements were according to the cumulative model described previously [24] and previously applied for other types of surfactants [25,26]. The thermodynamic parameters were calculated as described in [24].…”

Binding of a Ruthenium Complex to a Thioether Ligand Embedded in a Negatively Charged Lipid Bilayer: A Two‐Step Mechanism

“…Such a surface pressure variation is small compared to those reported for penetrating peptides, enzymes, or other lipophilic macromolecules interacting with lipid monolayers, for which DP is typically higher than 10 mN m À1 . [41][42][43][44][45][46][47] This qualitative comparison suggested that in-sertion of the metal complex into the membrane was at least limited. Such a conclusion was confirmed by another experiment showing that the surface pressure variation DP was independent of the initial surface pressure of the monolayer, P 0 .…”

“…In such cases, DP typically decreases when the initial surface pressure, P 0 , increases. [41,42,[48][49][50] In fact, the affinity of [2] 2 + for the DMPG monolayer is not high. It can be assumed that the ruthenium complex does not penetrate into the lipid monolayer, but rather migrates at the monolayer-water interface and adsorbs to the polar head-groups of the phospholipids, with or without substitution of the aqua ligand by a phosphate ligand.…”