Atomic force microscopy study of DNA flexibility on short length scales: smooth bending versus kinking

摘要: The apparently anomalous flexibility of DNA on short length scales has attracted a lot attention in recent years. We use atomic force microscopy (AFM) solution to directly study the bending statistics for small lengths down one helical turn. accuracy experimental estimates could be improved due large data volume and refined algorithm image processing measuring bend angles. It is found that, at beyond two turns (7 nm), well described by harmonic worm-like chain (WLC) model with persistence 56 nm. Below this threshold, AFM are also WLC assuming that measured angles limited physical width double helix. conclude behaves as uniform elastic rod even very scales. Strong bends kinks, melting bubbles other deviations from statistically negligible.