Dehydration Effect on the Recognition of Amphiphiles with Many Pendent Mannose Residues by Concanavalin A^†

Abstract

Amphiphiles which carried many pendent mannose residues as side chains were prepared by telomerization of 2-methacryloyloxyethyl D-mannopyranoside (MEMan, R: ) 6.5:3.5) using a lipophilic radical initiator. The mannose-carrying amphiphiles (DODA-PMEMan, DP (degree of polymerization) ) 3, 8, 14, and 17) incorporated in liposomes were recognized by a lectin from Canavalia ensiformis (Con A), which was proven by the increase in turbidity of the liposome suspension after mixing with the lectin. The recognition was largely affected by the degree of polymerization and surface density of the amphiphile in the liposomes. The association constant (Kas) between the mannose residue and Con A (2.2 × 10 5 M -1 for DODA-PMEMan (DP ) 17) at 25°C) was much larger than those for low molecular weight sugars (for example, methyl R-D-mannopyranoside, Kas ) 8.2 × 10 3 M -1 ) due to the "cluster effect". Thermodynamic parameters showed a significant contribution of positive entropy change to the effective sugar recognition in the liposome system, which was in contrast to the enthalpy-driven recognition of low molecular weight sugars by Con A. The positive entropy change could be attributed to the "dehydration" of both Con A molecule and the mannose-carrying polymer chains which were fixed to the gigantic and hydrophilic liposome surface.

Kinetic study on the binding of lectin to mannose residues in a polymer brush

“…It has very often been reported that lectin does not induce a coagulation of liposomes which incorporate sugar-carrying amphiphiles with a short spacer group between the sugar residue and a hydrophobic anchor [51][52][53]. This is due to a large steric hindrance preventing the huge lectin molecule from approaching the small sugar residues on the membrane surface.…”

Interaction of wheat germ agglutinin with an N-acetylglucosamine-carrying telomer brush accumulated on a colloidal gold monolayer

“…An azo-type radical initiator with dioctadecyl groups at both ends (DODA-501, Scheme 1(A)) [45][46][47][48] and the disulfidecarrying photo-iniferter (Cys-BDC, Scheme 1(B)) [23] were prepared as described earlier. A polymerizable phospholipid (bis(trans, trans-2,4-dioctadecadienoyl)phosphatidyl choline, DDPC) and 3-aminopropyl triethoxysilane (APTS) were purchased from Japan Fat & Oil Co., Tokyo, Japan and ShinEtsu Chemicals, Tokyo, Japan, respectively.…”

“…1(B)) [46][47][48]. The turbidity change of GlcNAc-carrying liposomes caused by the addition of WGA was dependent on the DP value of DODA-PMHGlcNAc: The addition of WGA to the dispersion of DODA-PMHGlcNAc (DP = 19) liposome induced a gradual increase in turbidity at 350 nm.…”

“…), it has often been reported that a lectin does not bind to an incorporated sugar-carrying amphiphile with a short spacer group between the sugar residue and a hydrophobic anchor [46][47][48], due to a large steric hindrance preventing the huge lectin from approaching the small sugar residue on the membrane surface. Therefore, CysPMHGlcNAc, which has a telomer chain with many pendent GlcNAc groups, was adopted as a "fly" to fish for WGA in this study.…”

Substrate Monolayers as Electrochemical Sensing Elements for α-Chymotrypsin

“…For example, amphiphiles which have many pendent sugar groups were prepared, and recognition of the sugar residues in the amphiphiles incorporated in liposomes by lectins and enzymes was examined (9)(10)(11)(12)(13)(14)(15).…”