| In principle, measuring the forces between individual molecules can provide novel insights into the specific interactions necessary to maintain or establish specific structure-function relationships. Recent advances in single molecule force spectroscopy using the scanning probe microscope have provided unique perspectives into the mechanics of protein unfolding and the dynamics of protein-protein interactions. Our work has focused primarily on membrane proteins and the nature of protein-membrane interactions. Using as our model system the well-studied cholera toxin and ganglioside receptor (GM1) complex, we have devised a strategy that allows us to measure the force required to extract the cholera toxin molecule from the GM1 molecules and the GM1 molecule from the membrane. Direct imaging confirmed extraction of a single cholera complex. Implications of this photoactivated coupling approach for the direct measurement of other single molecule interactions will be described. |
