The Interaction of l-Arabinose and d-Fucose with AraC Protein

The interaction of the inducer L-arabinose and an antiinducer D-fucose with araC protein is studied using spectrofluorimetric methods.AraC protein has a fluorescence spectrum typical of tryptophan-containing proteins.The fluorescence is quenched by L-arabinose suggesting that L- arabinose causes at least one conformational change in araC protein.The quenching of fluorescence does not occur in the presence of o-fucose.These observations are consistent with the model for positive control of the L-arabinose operon BAD by araC protein and suggest that the conformational