SPECTROSCOPY, IMAGING, OTHER TECHNIQUES |
Change in Rigidity in the Activated Form of the Glucose/ Galactose Receptor from E.coli: A Phenomenon That Will Be Key to the Development of Biosensors
Igor Sokolov 1*, Venkatesh Subba-Rao 1 and Linda A. Luck 1
1 Clarkson University
* To whom correspondence should be addressed. E-mail: isokolov{at}clarkson.edu.
Submitted on February 3, 2005
Revised on April 17, 2005
Accepted on 4 October 2005
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Abstract |
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Recently a periplasmic glucose/galactose binding protein, GGRQ26C, immobilized on gold surface has been used as an active part of a glucose biosensor based on quartz microbalance technique (QCM). 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.
Key Words:
atomic force microscopy, glucose biosensors, periplasmic receptors, quartz crystal microbalance
