Behavior of amphiphilic neoglycolipids at the air/solution interface - Interaction with a specific lectin

Qualitative and quantitative studies of monolayer properties are important to foster a better understanding of various biological phenomena in which lipid/protein/saccharide interactions are involved. In this framework, the interfacial behavior of monolayers of four synthetic derivatives of N-acetylglucosamine in mixture with dimyristoylphosphatidylcholine (DMPC) has been studied at the air/solution interface. The effect of the hydrophobic chain length and of the presence of a triethylene glycol spacer in neoglycolipid structures on both the miscibility of neoglycolipids with DMPC and on their interaction with a specific lectin has been investigated by surface tension measurements. The results reveal the occurrence of two distinct behaviors depending on the monolayer packing. At low surface coverages, all neoglycolipids appeared to be immiscible with DMPC as demonstrated by an expansion of the monolayers, independently of the molar fraction of a saccharide derivative in a mixture. In a more condensed packing state, the increase in the neoglycolipid/DMPC ratio above 50% led, with the exception of one studied system, to an ideal mixing of monolayer forming components. It has been observed that neoglycolipid and DMPC/neoglycolipid monolayers specifically interacted with wheat germ agglutinin (WGA) only when neoglycolipid saccharide moieties were separated one from the other by phospholipid molecules, and when the presence of a spacer ensured their successful accessibility to the lectin. (C) 1998 Elsevier Science B.V. All rights reserved.