DNA bending stiffness on small length scales.

Bending properties of short (15-90 bp), double-stranded DNA fragments are quantified using fluorescence resonance energy transfer and small angle x-ray scattering. Results from both types of measurements indicate that short double-stranded DNA fragments exhibit surprisingly high flexibility. These observations are discussed in terms of base-pair-level length fluctuations originating from dynamic features of Watson-Crick base pairs.