Monoclonal antibodies that block cell adhesion in Polysphondylium pallidum: reaction with L‐fucose, a terminal sugar in cell‐surface glycoproteins

Abstract

By permethylation analysis the linkages of L‐fucose and D‐mannose in the oligosaccharide residues of cell surface glycoproteins of Polysphondylium pallidum were determined. Mannose was found in terminal positions, in 1,2‐, 1,3‐ and 1,6‐intra‐chain linkages, and at branch points. Fucose was exclusively located at nonreducing ends. Fab of a monoclonal antibody, mAb 293, has been previously shown to inhibit cell adhesion in P. pallidum completely. Binding of this antibody to glycoprotein was blocked by L‐fucose, and at very high concentrations also by D‐mannose. The dissociation constant for the antibody‐fucose complex was Kd= 70μM, which was two orders of magnitude higher than estimated for the natural oligosaccharide. Antibody‐glycoprotein complexes dissociated in the presence of 100 mM L‐fucose with a half‐time of about 56s. The blockage by L‐fucose is taken as evidence that the adhesion‐blocking antibody binds to oligosaccharide end groups containing L‐fucose as the terminal sugar. Copyright © 1984, Wiley Blackwell. All rights reserved