Elasticity of strongly stretched ssDNA

We present a simple model which describes elastic response of single-stranded DNA (ssDNA) to stretching, including the regime of very high force (up to 1000 pN). ssDNA is modelled as a discrete persistent chain, whose ground state is a zigzag rather than a straight line configuration. This mimics the underlying molecular architecture and helps to explain the experimentally observed saturation of the stretching curve at very high force.