Associative properties of the Escherichiacoli galactose binding protein and maltose binding protein

The periplasmic galactose binding protein and maltose binding protein of $\text{Escherichia}\text{coli}$ are recovered mostly in dimeric form when purified, from osmotically-shocked bacteria, in the presence of protease inhibitors and 2-mercaptoethanol without dialysis and concentration of the shock fluid. The specific ligands, galactose (but not glucose) for galactose binding protein, and maltose for maltose binding protein, provoque the monomerisation of the dimeric native forms. These results are discussed in relation to the function of both binding proteins in transport and chemotaxis.