title: Change in rigidity in the activated form of the glucose/galactose receptor from Escherichia coli: a phenomenon that will be key to the development of biosensors.
abstract: Recently a periplasmic glucose/galactose binding protein, GGRQ26C, immobilized on a gold surface has been used as an active part of a glucose biosensor based on quartz microbalance technique. However the nature of the glucose detection was not clear. Here we have found that the receptor protein film immobilized on the gold surface increases its rigidity when glucose is added, which explains the unexpected detection signal. To study the rigidity change, we developed a new fast and simple method based on using atomic force microscopy (AFM) in tapping mode. The method was verified by explicit measurements of the Young's modulus of the protein film by conventional AFM methods. Since there are a host of receptors that undergo structural change when activated by ligand, AFM can play a key role in the development and/or optimization of biosensors based on rigidity changes in biomolecules.
authors.affiliation: Department of Physics, Clarkson University, Potsdam, New York 13699, USA. sokolov@clarkson.edu
authors.forename: Igor
authors.initials: I
authors.lastname: Sokolov
authors.forename: Venkatesh
authors.initials: V
authors.lastname: Subba-Rao
authors.forename: Linda A
authors.initials: LA
authors.lastname: Luck
mesh_terms: D001703:Biophysics / Q000379:methods*; D015374:Biosensing Techniques; D004563:Electrochemistry / Q000379:methods*; D004566:Electrodes; D004800:Enzymes, Immobilized; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism; D005947:Glucose / Q000737:chemistry; D006046:Gold / Q000737:chemistry; D008024:Ligands; D018625:Microscopy, Atomic Force; D015233:Models, Statistical; D009004:Monosaccharide Transport Proteins / Q000737:chemistry* / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011506:Proteins / Q000737:chemistry*
chemical_list: D004800:Enzymes, Immobilized; D029968:Escherichia coli Proteins; D008024:Ligands; D009004:Monosaccharide Transport Proteins; D011506:Proteins; C509064:mglB protein, E coli; D006046:Gold; D005947:Glucose