Non-covalent Immobilization of Desmoplakin Plakin Domain Molecules by Size-Selected Clusters for AFM Imaging

We exploit the immobilization of proteins by size-selected atomic gold clusters to examine the plakin domain of desmoplakin (PD), a human desmosomal protein that is mutated in severe skin diseases and cardiomyopathy, using atomic force microscopy (AFM) in the liquid phase. Contact mode AFM indicates that the PD does not establish a covalent bond size-selected gold nanocluster supported on a graphite substrate, but tapping mode AFM images indicate enhanced weak adsorption. The protein dimensions obtained are compared with predicted values based on electron microscopy, small-angle X-ray scattering (SAXS) and X-ray crystallographic studies.