Direct radiation effects to the amino acid side chain: EMR and periodic DFT of X-irradiated L-asparagine at 6 K

Comprehensive model for X-ray-induced damage in protein crystallography

Acquisition of X-ray crystallographic data is always accompanied by structural degradation owing to the absorption of energy. The application of high-fluency X-ray sources to large biomolecules has increased the importance of finding ways to curtail the onset of X-ray-induced damage. A significant effort has been under way with the aim of identifying strategies for protecting protein structure. A comprehensive model is presented that has the potential to explain, both qualitatively and quantitatively, the structural changes induced in crystalline protein at ∼100 K. The first step is to consider the qualitative question: what are the radiation-induced intermediates and expected end products? The aim of this paper is to assist in optimizing these strategies through a fundamental understanding of radiation physics and chemistry, with additional insight provided by theoretical calculations performed on the many schemes presented.