Binding of p-substituted-phenyl glycosides to the lectins from the pea and the lentil

The effect of p-substitution on the behaviour of phenyl α-D-mannopyranosides as specific ligands for the lectins from Pisum sativum (pea) and Lens culinaris (lentil) is reported. The binding affinities are related to the electronic properties of the substituents, expressed as the Hammett substituent constant (p = ?0.4). Inductive and mesomeric contributions are best considered separately. Neither steric hindrance nor hydrophobic binding of the substituents is observed. For the binding of the corresponding α-D-glucopyranosides to the Pisum sativum lectin, the same effect is maintained (p = ?0.4). In a series of p-substituted-phenyl β-D-glucopyranosides, the nature of the substituent has almost no effect on the binding to the Pisum sativum lectin.