Single molecule binding dynamics measured with atomic force microscopy

摘要

We present a new method to analyse simultaneous Topography and RECognition Atomic Force Microscopy data such that it becomes possible to measure single molecule binding rates of surface bound proteins. We have validated this method on a model system comprising a S-layer surface modified with Strep-tagU for binding sites and strep-tactin bound to an Atomic Force Microscope tip through a flexible Poly-Ethylene-Glycol linker. At larger distances, the binding rate is limited by the linker, which limits the diffusion of the strep-tactin molecule, but at lateral distances below 3 ran, the binding rate is solely determined by the intrinsic molecular characteristics and the surface geometry and chemistry of the system. In this regime, K_(on) as determined from single molecule TREC data is in agreement with K_(on) determined using traditional biochemical methods.