The goal of these experiments was to measure diffraction data from nanocrystals of GPCRs in order to determine their atomic resolution structures. We initially propose to use crystals where the structure has already been determined in order to validate the approach and results.
Crystals of beta-adrenergic receptor grown from lipidic cubic phase were placed in silicon nitride windows and inserted into the sample chamber. The window was rastered across the region where the x-ray beam was illuminating and data was collected at about 1Hz using 8 keV x-rays. The samples were maintained at room temperature. One major goal of these experiments were to develop the use of fixed targets, as opposed to injecting samples, as crystals of GPCRs and other membrane proteins are extremely difficult to grow and very few are available.
During this brief amount of beamtime (24 hours) significant time was used re-positioning the detector and then attempting to repair one of the modules in the detector that was not functioning. The total amount of useable beamtime was approximately 10 hours. None of the GPCR experiments produced diffraction, but some of the more standard test crystals that we attempted demonstrated weak diffraction. We did learn a great deal about the use of fixed targets which we will build on for future X-FEL beamtime at SACLA. |