Associative properties of the Escherichia coli galactose-binding protein and maltose-binding protein

Abstract

The ligand-binding characteristics of periplasmic galactose-binding protein and maltose-binding protein of Escherichia coli are analyzed. The saturation function was decreased upon increasing protein concentration and the monomer-dimer equilibrium was shifted towards the monomeric protein form upon an increase of the ligand concentration. An association constant K 0 = 6 10 8 M −1 was found for the galactose-binding protein. These data fit a monomer-dimer system in equilibrium, in which the monomer has a higher affinity for the ligand.