Recognition of Amphiphiles with Many Pendent Galactose Residues byRicinus communisAgglutinin

Amphiphiles which carry many pendent galactose residues as side chains were prepared by telomerization of 2-methacryloyloxyethyl β-D-galactopyranoside (MEGal) or 3-(2-methacryloyl aminoethylthio)propylD-galactopyranoside (MEPGal, α:β = 3.9:1) using a lipophilic radical initiator. The galactose-carrying amphiphiles (DP (degree of polymerization) = 15) incorporated in liposomes were recognized by a lectin fromRicinus communis(RCA₁₂₀), which was proven by the increase in turbidity of the liposome suspension after mixing with the lectin. The recognition was largely affected by the distance between the galactose residues and the polymer main chain, and the surface density of the amphiphile in the liposomes. The liposomes containing these galactolipids were not taken up by mouse peritoneal macrophages, probably due to a steric hindrance of polymer main chains from the uptake of D-galactose receptors on the macrophages.