Substrate-induced conformational changes of melibiose permease from Escherichia coli studied by infrared difference spectroscopy

Fourier transform infrared (FTIR) difference spectroscopy is used to study the substrate-induced structural changes of the melibiose permease (Me1B) from Escherichia coli reconstituted into liposomes. The analysis shows that the changes in the protonation state and/or in the environment of given carboxylic residues are induced by melibiose-Me1B interaction in the presence of cations.