Non-harmonic DNA bending elasticity is revealed by statistics of DNA minicircle shapes

Abstract

Unusual DNA elasticity has been observed in a few recent experiments for DNA under tight bending conditions. Here we present new experimental evidence demonstrating unusual DNA bending elasticity by analyzing the atomic force microscope (AFM) images of DNA minicircles of sizes 189 and 378 base-pairs that are relaxed on 2D surface. The DNA shape distributions are found in disagreement with the canonical 50 nm persistence length based worm-like chain (WLC) model. Instead, they are found in agreement with the recently proposed flexible defect excitation model and linear subelastic chain (LSEC) model. © 2010 World Scientific Publishing Company.