Segmented flow generator for serial crystallography at the European X-ray free electron laser
Austin Echelmeier, Jorvani Cruz Villarreal, M. Messerschmidt, Daihyun Kim, Jesse Coe, Darren Thifault, Sabine Botha, Ana Egatz-Gómez, Sahir Gandhi, Gerrit Brehm, Chelsie E. Conrad, Debra T. Hansen, Caleb Madsen, S. Bajt, J. Domingo Meza-Aguilar, Dominik Oberthür, Max O. Wiedorn, Holger Fleckenstein, Derek Mendez, J. Knoška, José M. Martín-García, Hao Hu, Stella Lisova, A. Allahgholi, Y. Gevorkov, Kartik Ayyer, Steve Aplin, Helen M. Ginn, H. Graafsma, Andrew J. Morgan, D. Greiffenberg, Alexander Klujev, Torsten Laurus, Jennifer Poehlsen, U. Trunk, D. Mezza, Bernd Schmidt, Manuela Kuhn, Raimund Fromme, J. Sztuk-Dambietz, Natascha Raab, Steffen Hauf, A. Silenzi, Thomas Michelat, Xu Chen, Cyril Danilevski, A. Parenti, Léonce Mekinda, Britta Weinhausen, Grant Mills, Patrik Vagovič, Yoonhee Kim, Henry Kirkwood, Richard Bean, Johan Bielecki, Stephan Stern, Klaus Giewekemeyer, Adam Round, Joachim Schulz, Katerina Dörner, Thomas D. Grant, Valerio Mariani, Anton Barty, Adrian P. Mancuso⋈, Uwe Weierstall, John C. H. Spence, Henry N. Chapman, Nadia A. Zatsepin, Petra Fromme, Richard A. Kirian, Alexandra Ros
Abstract
Serial femtosecond crystallography (SFX) with X-ray free electron lasers (XFELs) allows structure determination of membrane proteins and time-resolved crystallography. Common liquid sample delivery continuously jets the protein crystal suspension into the path of the XFEL, wasting a vast amount of sample due to the pulsed nature of all current XFEL sources. The European XFEL (EuXFEL) delivers femtosecond (fs) X-ray pulses in trains spaced 100 ms apart whereas pulses within trains are currently separated by 889 ns. Therefore, continuous sample delivery via fast jets wastes >99% of sample. Here, we introduce a microfluidic device delivering crystal laden droplets segmented with an immiscible oil reducing sample waste and demonstrate droplet injection at the EuXFEL compatible with high pressure liquid delivery of an SFX experiment. While achieving ~60% reduction in sample waste, we determine the structure of the enzyme 3-deoxy-D-manno-octulosonate-8-phosphate synthase from microcrystals delivered in droplets revealing distinct structural features not previously reported.