13C-NMR study of the binding of [1- 13C]galactose-labelled N-acetyllactosamine and [1- 13C]galactose-enriched hen ovalbumin to soybean agglutinin

Abstract

The binding of the titel compounds to soybean agglutinin was investigated using 13C-NMR spectroscopy. The equilibrium constant for the binding of N-acetyllactosamine was found to be smaller than that obtained for the binding of ovalbumin (1.1 · 10 3 vs. 7.4 · 10 3 M −1). Only two binding sites per lectin tetramer were determined for the binding of ovalbumin, which is half the number of bunding sites reported for the binding of small ligands to the lectin. Steric interference between the bulky ovalbumin molecules is believed to be the reason for the observed decrease in the apparent number of binding sites on the lectin.