Simple and Efficient Calculation of Scattering Intensities of Proteins in Solution from Atomistically Detailed Structures

Abstract

Solution scattering experiments provide signatures of the atomistic structure of proteins, nucleic acids, and biomolecular assemblies under near physiological conditions. Coarse-grained structural properties like shape and volume can be inferred from an essentially model-free analysis using information in the small-angle regime. The wide-angle regime offers higher resolution information which can be interpreted using atomistic models. A combination of time-resolved scattering experiments, molecular simulations, and ensemble refinement methods helps reveal structural changes in proteins as they perform their biological functions. To address this challenge, we developed a mathematically simple and computationally efficient method to calculate the scattering intensity of atomistically detailed structures of proteins in solution. Compared to other methods, our method, which is based on Debye's formula, has the advantage that there is no trade-off between computational efficiency and accuracy in the promising wide-angle regime. We present results for a variety of proteins and different water models and discuss some fundamental differences in interpretation of small- and wide-angle data.