Radiation damage in protein crystals at low temperature

Abstract

This paper describes the study of the effects of radiation damage on the quality of data collected from a protein crystal at 100 K. It is shown that radiation damage causes measurable effects in the diffraction pattern. This implies that, even at liquid nitrogen temperatures, there is a limit to the size of a crystal from which a complete data set can be collected.

Experimental determination of the radiation dose limit for cryocooled protein crystals

“…This difference is not thought to be due to temperature rises in the crystals: by using the lumped model described by Kuzay et al (16), RADDOSE predicts a temperature rise of Ͻ5 K for holoferritin at the highest dose rate used. Previous measurements using a white beam of flux density of 2 ϫ 10 15 photons per s͞mm 2 found no evidence of beam heating in a 100 K crystal sample (17). Two effects may be responsible for the measured dose limit difference: first, the uncertainty in the holoferritin dose calculation, which is greater because of the large iron content, and second, the dose is a parameter that takes only the deposited energy into account but none of the possible chemical processes.…”

Rapid X-ray Photoreduction of Dimetal-Oxygen Cofactors in Ribonucleotide Reductase

“…The respective doses (at 80 K) are at least 100 times smaller than those resulting in radiation damage of amino acid groups (46,105).…”

A Description of Imperfections in Protein Crystals

“…A highly perfect tetragonal crystal of lysozyme at room temperature was used as a standard, although it was not expected that the experimental setup would provide information on the parameters in this crystal. The preparation of the crystals and freezing techniques were as described in Gonzalez & Nave (1994). The primary aim was to illustrate how the various parameters could be obtained by observing significant effects for the divergence of the diffracted beam from a crystal with high mosaicity.…”