Complex carbohydrate-lectin interaction at the interface: a model for cellular adhesion. I. Effect of vesicle size on the kinetics of aggregation between a fatty acid conjugate of lectin and a liposomal asialoganglioside

Abstract

Two types of phospholipid vesicles capable of mutual recognition have been tailor-made to serve as a model system for the study of carbohydrate-mediated cellular adhesion. One of the vesicles contained a fatty acid conjugate of a galactose specific lectin (lectin vesicle_ and the other an asialoganglioside with a reactive terminal galactose residue (galactose vesicle). The kinetics of aggregation of these two types of vesicles was followed by monitoring time-dependent change in turbidity. A 10–100-fold enhancement in the forward rate constant ( k f ranging from 7.1 · 10 5 to 4.5 · 10 7 M −1 · s −1 at 27° C) was observed when compared with that for the lectin-galactose system in solution ( k t) being 4.5 · 10 5 M −1 · s −1), reported in the literature. A study of the influence of vesicle size on the rate of aggregation showed that enhancement depended on the curvature of the galactose vesicle rather than the density of asialoganglioside suggesting a possible diffusion in the plane of the membrane. The ratio, k f/ k d is found to be approx. 10 10 M −1 indicating that the formation of multiple bonds plays a role for stable adhesion.