A hands-free capillary system for protein crystallography from crystallization to data collection

With the goal of producing a fully automated experimental system for protein X-ray crystallography, a hands-free system is presented in which all aspects of crystallographic experiments, from crystallization to diffraction data collection, are performed within a modified X-ray glass capillary. Because it eliminates the manual handling of crystals, this capillary system allows the user to evaluate the quality of protein crystals more accurately. The capabilities of this capillary system were examined using the TTHB049 protein from Thermus thermophilus HB8 and xylanase from Trichoderma longibrachiatum. Each protein was successfully crystallized in the capillary and three complete diffraction data sets were collected at 100 K without direct manual intervention. The diffraction data from the capillary system were superior, in terms of both quality and reproducibility, when compared with data from conventional cryoloop systems. In addition, the capillary system allows the in situ heavy-atom derivatization of protein crystals, i.e. the TTHB049 crystals were successfully derivatized with K₂PtCl₄ within the capillary.