How to know radiation damage?

[Debarati92]

Hello! I was wondering how does one decide if there has been a radiation damage just by looking in the SAXS profile? What are the things to look for in the SAXS profile to identify damage? Additionally, can anyone plz recommended an article or book which talks about radiation damage.

[andreashlarsen]

Usually, SAXS is measure in short frames, that are then merged. In that case, the frames can be compared before they are merged (see tutorial data reduction), so see if changes have occured from the first to the last frame.

That said, beam damage often result in relatively large structures of unfolded and aggregated protein - which will give an upturn at low q (and if severe, streching towards higher q). Check out for example:
https://pmc.ncbi.nlm.nih.gov/articles/PMC4886981/.

here are good advice on how to avoid beam damage:
https://www.embl-hamburg.de/biosaxs/sample.html