Assessing protein-specific radiation damage in time-resolved X-ray solution-scattering experiments at high-brilliance synchrotrons using fast detector readout.

Time-resolved X-ray solution scattering (TR-XSS) enables tracking of protein structural dynamics but can suffer from radiation damage when performed with continuous X-ray beam exposure at multipurpose small-angle X-ray scattering (SAXS) beamlines. Here, we systematically assess how protein concentration, exposure time, X-ray dose and beam focusing influence the stability of adenylate kinase (AdK) during TR-XSS at CoSAXS at the MAX IV Laboratory. Static SAXS measurements from 2.5 to 21 mg ml-1 showed only minor interparticle effects, establishing suitable concentrations for TR-XSS. Under detector-focused conditions, AdK irradiated at room temperature remained stable up to 3.13 kGy, with consistent absolute and difference scattering profiles over 50 ms. In contrast, focusing the beam directly on the sample increased the absorbed dose to 21.3 kGy and produced clear signatures of radiation damage, which included low-q intensity loss and increasing deviation from the low-dose condition. These results identify practical system-specific dose limits and highlight beam focusing as a key determinant of sample integrity. The workflow presented here provides general guidelines for minimizing radiation artifacts in TR-XSS on multipurpose SAXS beamlines.