Diamond Annual Review 2023/24

19 D I A M O N D L I G H T S O U R C E A N N U A L R E V I E W 2 0 2 3 / 2 4 Warming up to room-temperature crystallography X-ray crystallography is one the most common techniques in the structural biologist’s toolkit for resolving protein structure. However, X-rays can warm up and damage a crystal before collecting enough data, so scientists began cryopreserving samples to endure the beam for longer. This strategy has proven effective for a plethora of proteins, but many adopt spurious shapes at cold temperatures, and some protein crystals are too fragile to freeze. To expand the technique to encompass more proteins, the team at the Versatile Macromolecular Crystallography in situ (VMXi) beamline probe crystals at room temperature instead. By avoiding the time- consuming cryopreservation step, their strategy benefits from being high throughput, allowing arrays of crystals to be swiftly screened and resolved. Additionally, their technique avoids the structural artefacts brought about by cryopreservation and allows dynamic changes in protein shape to be captured. VMXi users have harnessed the strategy to resolve the structure of proteins crystallised using viscous media, cytochromes carrying X-ray sensitive metal groups, and unusually lengthy antibodies in cattle. With many applications, room-temperature crystallography holds promise for resolving some of the toughest proteins in the future. Mikolajek, H. et al. DOI: 10.1107/S2052252523003810 Figure: Examples of protein crystals imaged within crystallization plates. Crosshairs represent positions selected for data collection and crystal size is indicated by a scale bar. The crystals are (a) PhnD1, (b) AbD08, (c) NCOA7 crystal form I, (d) NCOA7 crystal form II, (e) PHCP and (f ) TTCP. Crystal sizes vary between 10 and 500 µmmaximum dimension. The scale bar is ∼ 100 µm.