β‐Cyclodextrin‐Mediated Removal of Soy Phospholipids from the Air–Water Interface

Abstract

Binding of soy phosphatidylcholine (PC) and phosphatidylinositol (PI) with b-cyclodextrin (bCD) was studied using a spread monolayer technique at the airwater interface. First, surface pressure (p) versus surface concentration (C) isotherms of both PC and PI were characterized by forming spread monolayers on an aqueous subphase. PC and PI monolayers reached saturation at C of 1.98 and 3.24 lmol/m 2 , respectively, at 25°C. Subsequently, desorption of PC or PI from the spread monolayer in the presence of 2-14 mM bCD in the subphase was studied by measuring changes in p of monolayer. This desorption was indicative of a complex formation between bCD and PC or PI. The amount of PC or PI bound to bCD was determined by converting the net change in p to C by using p-C isotherms. From the saturated monolayers at the air water-interface, approximately 30% of PC and 50% of PI could be removed by 14 mM bCD. It was calculated that the free energy change required to transfer a PL from the monolayer at air-water interface to the aqueous phase in presence of bCD was decreased by 6-7 kcal/mol. Hydrolysis of PC in the monolayer by phospholipase A 2 (PLA 2 ) improved extraction efficiency of bCD. By incorporating 2.29 lM PLA 2 and 10 mM bCD in subphase, up to 80% of PC monolayer could be desorbed from the air-water interface. These results are discussed in terms of the potential use of bCD to remove PLs bound to soy protein.

Cholesterol Depletion from a Ceramide/Cholesterol Mixed Monolayer: A Brewster Angle Microscope Study

“…The depletion of cholesterol depends on the type of lipids involved8 (head group size, charge, dipole moment, chain length, unsaturation level etc.). MβCD binds to different lipids by absorbing their hydrophobic tails within the MβCD cavity instead of attaching to their head-groups14816. Clearly, the attachment of cholesterol to MβCD strongly depends on the head-group size of the lipids surrounding the cholesterol molecules.…”

“…Cholesterol depletion by cyclodextrins (CDs) from biomembranes has attracted a lot of attention due to its biological and medical relevence123456789101112. Among the members of CD families (e.g.…”

“…So far, a significant number of studies focused on phospholipid (e.g. DMPC/DPPC/DOPC)-mixed membranes/vesicles to test cholesterol depletion by MβCDs141617. However, to the best of our knowledge, MβCD-mediated cholesterol depletion from a C16-ceramide/Cholesterol (C16-Cer/Chol) mixed monolayer has not been reported yet, even though C16-Cer/Chol domains are biologically relevant because C16-ceramide and cholesterol are two major components in the liquid ordered (L 0 ) micro-domains (rafts) in biomembranes1819202122.…”