Abstract: Galactose/glucose binding protein (GBP) is synthesized by Escherichia coli (E. coli) in a precursor form in the cytoplasm and exported into the periplasmic space upon cleavage of the 23 amino acid leader sequence. GBP binds galactose and glucose in a highly specific manner. The ligand induces a binge motion in GBP and the resultant protein conformational change constitutes the basis of the sensing system. Biosensors based upon GBP have been developed. These biosensors use various analytical signals, including option (i.e., fluoresecence) and electrochemical. The analytical methods were used to determine the amount of glucose present.