Modified Nextal crystallization device for in situ inspection of protein crystal quality

The modification and use of the Nextal crystallization device for checking the diffraction quality of protein crystals in situ is described. Using the modified device, crystals in the crystallization drop can be exposed to X-rays directly to observe the diffraction quality without physical damage to the crystal. If the crystals in the drop are well separated, not only the resolution limit of the crystal is estimated, but also determination of the space group and the cell parameters is possible.