BIOT 140 |
| There is great interest in understanding and controlling the structural behavior of adsorbed and covalently-bound proteins. Applications include biosensors, protein microarrays, single molecule spectroscopy and atomic force microscopy (AFM) with proteins and other biophysical studies. Adsorbed proteins on surgical instruments are a potential source of transmission of conformational diseases like Alzeheimer's, CJD and type II diabetes. Misfolded proteins adhere to surfaces more strongly than their natively folded analogs. Also, proteins adsorb on hydrophobic surfaces to a greater extent than on hydrophilic surfaces. Surface properties, such as exposed functional groups, surface restructuring and surface topology, affect protein folding thermodynamics. Here, we report on the stability of chemically-immobilized hen egg lysozyme (Lys) onto a gold substrate using AFM in force-mode (i.e. a 10 µm diameter borosilicate sphere attached to the cantilever tip) so as to measure the adhesion energy between the protein and various functionalized surfaces. The structure of the immobilized Lys was thermally and chemically perturbed during the force measurements and the protein's binding energy with the different chemical moieties measured. Adhesion energies were plotted against the forcing function i.e. concentration of chemical denaturant or temperature. Results of thermal and chemical denaturation of immobilized lysozyme were then compared with those in solution phase. Effects of both stabilizing and destabilizing osmolytes on immobilized protein were also analyzed. |
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Biophysical and Biomolecular Symposium: Protein Chemical Instability
8:00 AM-11:05 AM, Tuesday, August 21, 2007 BCEC -- 106, Oral
Division of Biochemical Technology |