| Summary: | 碩士 === 國立臺灣師範大學 === 化學系 === 99 === There is an increasing amount of evidence showing links between protein mutations and biological function disorders. In view of the fact that mutations may cause surface conformation changes to proteins, we attempt to characterize mutated proteins with magnetic mode atomic force microscopic techniques (MFM) by using apoferritin to mimic mutated ferritin. Preliminary results based on ferritin and apoferritin show that MFM is a sensitive tool, responding to ferritin and apoferritin protein distinctly in terms of phase shift. Although both show similar corona-shaped images, we consider that the images are contributed more from the fringing effects than the magnetic iron core. Despite this, applying external electric field to both proteins can substantially enhance their MFM images, in which ferritin shows a stronger dependence on the applied biases than its demetalated counterpart. We also characterize ferritin and apoferritin with the conductive mode AFM (CFM). Based on the surface conductivity obtained from CFM and the phase shifts in MFM, we find that ferritin and apoferritin can be differentiated. For verification, we also compare the data with those from DNA and platinum miniatures. According to these results, we consider MFM and CFM are potential alternatives for the analysis of mutated proteins besides other existing surface techniques.
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