I would suggest looking up texts of radiation chemistry, not radiochemistry. A good website to start may be the radiation chemistry laboratory at Univ. of Notre Dame. Those guys have done a lot of stuff on radiolysis of different materials. Another way to attack this may be instead to look at reactions of different radiation produced radicals with aminoacids, i.e. peroxide, hydroxyl radical, ozone, superoxide etc etc. Also, most of these things are tied into research on antioxidants such as vitamin C (ascorbic acid) etc. You should however be able to find a text on radiation chemistry that will deal with amino acids. Hope this was helpful.