Radiation Damage to Proteins: Changes on the Primary and Secondary Structure Level

Abstract

Specimens in the electron microscope are inevitably exposed to an intense flux of ionizing radiation which more or less dramatically deteriorates the structure under investigation. While optimists may comfort themselves by feeling that, irrespective of some damage, the specimens still retain quite a close resemblence to the original structure, pessimists suspect that all significant 'high resolution' information is destroyed. A rational approach towards reconciling these extreme views is to ask what the specimen is, chemically speaking, when a certain number of electrons has traversed it. The assessment of the limits of structural fidelity to be expected for a given class of specimens is the prime objective of radiation damage research as it pertains to electron microscopy. Unravelling the sequence of events leading to the final product is another aim which, besides academic satisfaction, may have some important repercussions in as much as an understanding of the mechanisms controlling structural reorganization might facilitate the design of remedial procedures for reducing damage, which we need so badly.