Separating the effects of temperature and absorbed X-ray dose on unit-cell volume.

The behaviour of the unit-cell volume of crystals of the iron-storage molecule ferritin, both in the apo and the holo form, and of influenza A virus subtype N9 neuraminidase at 100 K and over a controlled cryo-temperature series was investigated. The purpose of this study was to separate out the effects of dose and temperature on the protein by assessing the changes in the unit-cell volume. Over the wide range of X-ray doses examined in this work, the irreversible effect of dose on the unit-cell volume could be distinguished from the reversible (below 160 K) temperature-induced effects. Specific structural damage effects were not reversible.