Molecular recognition. IV. The binding of the Lewis b human blood group determinant by a hybridoma monoclonal antibody

Abstract

A commercial hybridoma monoclonal anti-Lewis b antibody appears to accept the Lewis b human blood group determinant (αLFuc(1→2)βDGal(1 → 3)[αLFuc(1 → 4)]βDGlcNAc--) by involving OH-3 of the βDGal unit and OH-2 of the αLFuc(1 → 2) unit in a key polar interaction at the periphery of a large wedge-shaped lipophilic surface that extends about the tetrasaccharide and essentially leaves 5 of the 8 other hydroxyl groups in contact with the aqueous phase. It is proposed that the three remaining hydroxyl groups, namely, OH-4of the βDGal unit, OH-3 of the αLFuc(1 → 4) unit, and OH-4 of the αLFuc(1 → 2) unit, become intramolecularly hydrogen bonded for acceptance into a hydrophobic environment. The results are taken as further circumstantial evidence that the stability of the complex is mainly related to the establishment of dispersion forces of attraction between complementary lipophilic surfaces provided by the oligosaccharide and the protein. These forces are expected to be stronger than those prior to binding between the amphiphilic surfaces that are involved and water.