Bending of DNA is a feature essential to the function of many DNA-binding proteins. Bending angles can be estimated with a
variety of techniques, but most directly from images obtained using scanning force microscopy (SFM). Direct measurement of
the bending angle using a tangent method often produces angles that deviate significantly from values obtained using other
techniques. Here, we describe the application of SFM in combination with simulations of DNA as a means to estimate protein-induced
bending angles in a reliable and unbiased fashion. In this manner, we were able to obtain accurate estimates for the bending
angles induced by nuclear factor I, octamer-binding transcription factor 1, the human XPC-Rad23B complex.