European XFEL GmbH 3 articles published in JoVE Biochemistry Crystallization and Structural Determination of an Enzyme:Substrate Complex by Serial Crystallography in a Versatile Microfluidic Chip Raphaël de Wijn1,4, Kévin Rollet1,2, Vincent Olieric3, Oliver Hennig2, Nicola Thome1, Camille Noûs1, Caroline Paulus1, Bernard Lorber1, Heike Betat2, Mario Mörl2, Claude Sauter1 1Université de Strasbourg, Architecture et Réactivité de l’ARN, UPR 9002, CNRS, Institut de Biologie Moléculaire et Cellulaire, 2Biochemistry and Molecular Biology, Institute for Biochemistry, Leipzig University, 3Paul Scherrer Institute, Swiss Light Source, 4European XFEL GmbH A versatile microfluidic device is described that enables the crystallization of an enzyme using the counter-diffusion method, the introduction of a substrate in the crystals by soaking, and the 3D structure determination of the enzyme:substrate complex by a serial analysis of crystals inside the chip at room temperature. Engineering Cryogenic Liquid Jets for High Repetition Rate Discovery Science Chandra B. Curry*1,2, Christopher Schoenwaelder*1,3, Sebastian Goede4, Jongjin B. Kim1, Martin Rehwald5,6, Franziska Treffert1,7, Karl Zeil5, Siegfried H. Glenzer1, Maxence Gauthier1 1SLAC National Accelerator Laboratory, 2University of Alberta, 3Friedrich-Alexander-Universität Erlangen-Nürnberg, 4European XFEL, 5Helmholtz-Zentrum Dresden-Rossendorf, 6Technische Universität Dresden, 7Technische Universität Darmstadt This protocol presents the operation and principles of micron-scale cylindrical and planar cryogenic liquid jets. Until now, this system has been used as a high repetition rate target in laser-plasma experiments. Anticipated cross-disciplinary applications range from laboratory astrophysics to material science, and eventually next-generation particle accelerators. Chemistry An Experimental Protocol for Femtosecond NIR/UV - XUV Pump-Probe Experiments with Free-Electron Lasers Daniel Rolles1, Rebecca Boll2,3, Benjamin Erk2, Dimitrios Rompotis2, Bastian Manschwetus2 1J.R. Macdonald Laboratory, Department of Physics, Kansas State University, 2Deutsches Elektronen-Synchrotron DESY, 3European XFEL GmbH This protocol describes the key steps for performing and analyzing pump-probe experiments combining a femtosecond optical laser with a free-electron laser in order to study ultrafast photochemical reactions in gas-phase molecules.