Radiolysis of proteins in the solid state

Under irradiation, proteins are affected by direct and indirect effects of ionizing radiations. When these macromolecules are in liquid solution, direct effects can be neglected and the indirect effects are predominant. On the contrary, in solid state, proteins are ionized mainly by direct interaction (11). 

Proteins in solid state can be found in different forms, lyophilized or in frozen aqueous solution. Under irradiation, lyophilized proteins mostly aggregate, as was shown for egg-white lysozyme irradiated at room temperature (13, 14, 15, 16). On the contrary, irradiation of frozen protein solutions gives rise to fragmentation (11, 16 and references therein). Rupture of the N-Ca bond of the polypeptide chain seems to be responsible for fragmentation, as it was observed for homopolymers irradiated at 77K (17). 

---

Terryn H, Deridder V, Sicard-RoseUi C, Tilquin B, Houee-Levin C. (2005) Radiolysis of proteins in the solid state An approach by EPR and product analysis. J Synchrotron Rad 12 292-298. 

---