46th iCeMS Seminar/CeMI Seminar Series 14: Yoko Yamakoshi, PhD

CeMICenter for Meso-Bio Single-Molecule Imaging

Tripod-shaped molecules were designed for chemical modification of the surface of probes used for atomic force microscopy (AFM). These chemically functionalized tips were used for chemical force spectroscopy (CFS) measurements of the ligand-protein receptor interaction in a biotin-NeutrAvidin model system. We demonstrate that by using this unique tripodal system, we can achieve significantly lower density of ligand on the AFM tip apex, which is optimal for true single molecule measurements. Furthermore, the molecular tripods form highly stable bonds to the AFM probes, leading to more robust and reproducible unbinding force data, thereby addressing one of the challenges in CFS studies. Histogram analysis of the hundreds of collected unbinding forces showed a specific distribution with a peak force maximum at ~165 pN, in good agreement with the previously reported data of single rupture events of biotin-avidin. We compared these molecular tripod tips with molecular monopod. The results showed that the molecular tripods are more robust for repeated measurements. The distinct biotin-avidin force maximum was not observed in the control experiments. This indicated that the force distribution observed for molecular tripods corresponds to the specific rupture force between biotin and avidin. The improved robustness of molecular tripods for CFS will provide benefits in other ligand-receptor unbinding studies, including those of transmembrane receptor systems, which require high resolution, sensitivity, and reproducibility in force spectroscopy measurements.

Lecturer Yoko Yamakoshi, PhD
Assistant Professor, Department of Radiology / Department of Chemistry
University of Pennsylvania, USA
Title Synthetic Chemistry for AFM Tip Modification and Biological Applications
Date / Time March 3, 2010 / 10:30-11:30
Venue 2nd floor Seminar Room (#A207), Main Building
iCeMS Complex 1, Kyoto University
Directions
Flyer PDF FilePDF (220KB)
Host Institute for Integrated Cell-Material Sciences (iCeMS), Kyoto University
Contact iCeMS Harada Lab
harada-g@icems.kyoto-u.ac.jp