Small angle scattering as a tool to study the thermal denaturation of DNA

Abstract : DNA thermal denaturation is the breaking of the base pairs, leading to a splitting of the two strands of the double helix. While it is easy to measure the fraction of open base pairs (f) versus temperature, determining the fraction (p) of fully open molecules is much harder. Previously, the simultaneous recording of f and p could only be achieved for special sequences. We show that small angle scattering of X-rays or neutrons allows the measurement of p for any sequence. We illustrate the method with a SAXS investigation of two sequences designed to exhibit different melting profiles and compare the SAXS data with nano-calorimetric measurements of the melting curve.