Exploring SANS as a novel approach to investigate protein stability with Hydrogen-Deuterium Exchange

Hydrogen deuterium exchange, (HDX) is of increasing interest as it provides useful information of protein dynamics in solution. Recently, the rapid development of HDX mass spectrometry (HDX-MS) shows a great potential to understand the protein flexibility and conformational changes by investigating the exchange of amide hydrogens with deuterium. Due to the very large difference of the neutron scattering cross section between H and D, techniques such as small angle neutron scattering (SANS), can offer an alternate approach to monitoring HDX. Unlike HDX-MS, SANS allows for the continual measurement of HDX over time and is a non-invasive technique to investigate the HDX in solution. Even though SANS does not have the sensitivity to study the amino acid sequence specific exchange kinetics, it could provide the spatial distribution information of exchangeable protons in a protein, as a function of the exchange time. With the use of SANS, we probed the HDX of a couple of proteins over the course of a day. Novel analysis approach is designed to extract the exchange kinetics and the spatial distribution of exchangeable protons, from SANS. Additionally, the effect of the sample conditions, such as the temperature and buffer conditions, on the HDX will be presented.