IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Biomaterials Wednesday Sessions
       Session BI+NS-WeA

Paper BI+NS-WeA3
Single and Multiple Molecule Binding Forces Measured Using Modified Atomic Force Microscope Cantilevers

Wednesday, October 31, 2001, 2:40 pm, Room 103

Session: Nanobiology
Presenter: R.G. Rudnitsky, Stanford University
Authors: R.G. Rudnitsky, Stanford University
F. Drees, Stanford University
K.S.H. Wu, Stanford University
T.D. Perez, Stanford University
W.J. Nelson, Stanford University
T.W. Kenny, Stanford University
Correspondent: Click to Email
Although the energies and forces controlling protein interactions are frequently inferred from traditional equilibrium and kinetic measurements, recent developments in chemical force microscopy allow for the direct quantification of the ranges and magnitudes of binding forces between individual protein pairs and between groups of proteins. We report here on the use of specially modified Atomic Force Microscope cantilevers to measure bond strength down the single-molecule level, with pico-Newton force resolution, using the cellular binding protein E-cadherin as our model system. Previous E-cadherin studies focused on the energetics of large systems of molecules, typically in-vivo, to demonstrate their role in cellular adhesion. Our novel AFM force spectroscopy method tracks the unbinding process of single and multiple E-cadherin molecules under force loads, to quantitatively differentiate specific from non-specific binding, and single and multiple binding events, in surface bound protein. The measurements isolate the extracellular domain of the molecule, thought to be essential for stable cell adhesion, and demonstrate the dependence of binding forces at a molecular level on Ca++ concentrations. The data correlates the relationship of homophilic E-cadherin adhesion to surface protein density in a way not previously demonstrated in cellular studies.