engleski

Recognition of Adamantyl-anchored Mannosylated- tripeptides on Liposome Surface by Concanavaline A

The liposomes with encapsulated mannosylated adamantyltripeptides, namely (2R)-N-[3-(α-D- mannopyranosyloxy)-2-methylpropanoyl]-D, L- (adamant-2-yl)glycyl-L-alanyl-D-isoglutamine] were examined. In order to determine the entrapment efficiency, size, shape and surface changes on the liposomes, HPLC, dynamic light scattering (DLS) and atomic force microscopy (AFM) were used. We have previously shown the interaction of immunostimulating adamantyltripeptides and phospholipids in liposomal bilayers. Now, we were primarily interested to study incorporation profile of mannosylated adamantyltripeptides. We have demonstrated that the adamantyl moiety, due to its liphophilic properties, penetrates into the lipid core of the bilayer while the hydrophilic part with the mannosyl moiety is exposed on the liposome surface. After concanavalin A (Con A), a lectin, which specifically binds -D-mannosyl residues, was added to the liposome preparation, increase in liposome size and appearance of aggregates has been observed. The enlargement of liposomes was ascribed to the specific binding of the Con A to the mannose present on the surface of the prepared vesicles. The AFM analysis revealed that the adamantyltripeptide molecules grouped into small domains that raise above the bilayer surface. The molecule size and molecular geometry, as well as the hydrophilic and hydrophobic surfaces in the structure of mannosylated adamantyltripeptides, are responsible for arrangement of molecules in the lipid bilayer. This approach might be a useful model for investigation of specific protein interactions with membrane receptors. Also, the adamantyl moiety may be considered as a potential membrane anchor for different carbohydrate or other molecules of interest, which could be bound on it and thus exposed on liposome surfaces and as such used in targeted drug delivery.

Adamantane; Mannose; Liposome; Adamantyltripeptides; AFM

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