Ligand-induced conformational changes in lactose repressor: a fluorescence study of single tryptophan mutants

The regions of the lac repressor protein involved in conformational changes in response to ligand binding in Escherichia coli were determined. Mutant repressor proteins with single tryptophans were produced by mutating each of the two native tryptophan residues to tyrosine and altering the residue of interest to tryptophan. Findings showed that in the investigated areas of the lac repressor, the inducer-bound form is different from the conformation of the unliganded form.