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Instruments / Technical Area	Publication Details	Published
	Femtosecond X-ray coherent diffraction of aligned amyloid fibrils on low background graphene Carolin Seuring , Kartik Ayyer , Eleftheria Filippaki , Miriam Barthelmess , Jean-nicolas Longchamp , Philippe Ringler , Tommaso Pardini , David H. Wojtas , Matthew A. Coleman , Katerina Dörner , Silje Fuglerud , Greger Hammarin , Birgit Habenstein , Annette E. Langkilde , Antoine Loquet , Alke Meents , Roland Riek , Henning Stahlberg , Sébastien Boutet , Mark S. Hunter , Jason Koglin , Mengning Liang , Helen M. Ginn , Rick P. Millane , Matthias Frank , Anton Barty , Henry N. Chapman Nature Communications 9 DOI: 10.1038/s41467-018-04116-9 Open Access Show Abstract ▼ Abstract: Here we present a new approach to diffraction imaging of amyloid fibrils, combining a free-standing graphene support and single nanofocused X-ray pulses of femtosecond duration from an X-ray free-electron laser. Due to the very low background scattering from the graphene support and mutual alignment of filaments, diffraction from tobacco mosaic virus (TMV) filaments and amyloid protofibrils is obtained to 2.7 Å and 2.4 Å resolution in single diffraction patterns, respectively. Some TMV diffraction patterns exhibit asymmetry that indicates the presence of a limited number of axial rotations in the XFEL focus. Signal-to-noise levels from individual diffraction patterns are enhanced using computational alignment and merging, giving patterns that are superior to those obtainable from synchrotron radiation sources. We anticipate that our approach will be a starting point for further investigations into unsolved structures of filaments and other weakly scattering objects.	May 2018
	High-speed fixed-target serial virus crystallography Philip Roedig , Helen M. Ginn , Tim Pakendorf , Geoff Sutton , Karl Harlos , Thomas S. Walter , Jan Meyer , Pontus Fischer , Ramona Duman , Ismo Vartiainen , Bernd Reime , Martin Warmer , Aaron S. Brewster , Iris D. Young , Tara Michels-clark , Nicholas K. Sauter , Abhay Kotecha , James Kelly , David J. Rowlands , Marcin Sikorsky , Silke Nelson , Daniel S. Damiani , Roberto Alonso-mori , Jingshan Ren , Elizabeth E. Fry , Christian David , David I. Stuart Stuart , Armin Wagner , Alke Meents Nature Methods 8 DOI: 10.1038/nmeth.4335 Show Abstract ▼ Abstract: We report a method for serial X-ray crystallography at X-ray free-electron lasers (XFELs), which allows for full use of the current 120-Hz repetition rate of the Linear Coherent Light Source (LCLS). Using a micropatterned silicon chip in combination with the high-speed Roadrunner goniometer for sample delivery, we were able to determine the crystal structures of the picornavirus bovine enterovirus 2 (BEV2) and the cytoplasmic polyhedrosis virus type 18 polyhedrin, with total data collection times of less than 14 and 10 min, respectively. Our method requires only micrograms of sample and should therefore broaden the applicability of serial femtosecond crystallography to challenging projects for which only limited sample amounts are available. By synchronizing the sample exchange to the XFEL repetition rate, our method allows for most efficient use of the limited beam time available at XFELs and should enable a substantial increase in sample throughput at these facilities.	Jun 2017
	TakeTwo : an indexing algorithm suited to still images with known crystal parameters Helen Mary Ginn , Philip Roedig , Anling Kuo , Gwyndaf Evans , Nicholas K. Sauter , Oliver P. Ernst , Alke Meents , Henrike Mueller-werkmeister , R. J. Dwayne Miller , David Ian Stuart Acta Crystallographica Section D Structural Biology 72, 956 - 965 DOI: 10.1107/S2059798316010706 Open Access Show Abstract ▼ Abstract: The indexing methods currently used for serial femtosecond crystallography were originally developed for experiments in which crystals are rotated in the X-ray beam, providing significant three-dimensional information. On the other hand, shots from both X-ray free-electron lasers and serial synchrotron crystallography experiments are still images, in which the few three-dimensional data available arise only from the curvature of the Ewald sphere. Traditional synchrotron crystallography methods are thus less well suited to still image data processing. Here, a new indexing method is presented with the aim of maximizing information use from a still image given the known unit-cell dimensions and space group. Efficacy for cubic, hexagonal and orthorhombic space groups is shown, and for those showing some evidence of diffraction the indexing rate ranged from 90% (hexagonal space group) to 151% (cubic space group). Here, the indexing rate refers to the number of lattices indexed per image.	Aug 2016
I03-Macromolecular Crystallography	Room-temperature macromolecular crystallography using a micro-patterned silicon chip with minimal background scattering Philip Roedig , Ramona Duman , Juan Sanchez-weatherby , Ismo Vartiainen , Anja Burkhardt , Martin Warmer , Christian David , Armin Wagner , Alke Meents Journal Of Applied Crystallography 49, 968 - 975 DOI: 10.1107/S1600576716006348 Show Abstract ▼ Abstract: Recent success at X-ray free-electron lasers has led to serial crystallography experiments staging a comeback at synchrotron sources as well. With crystal lifetimes typically in the millisecond range and the latest-generation detector technologies with high framing rates up to 1 kHz, fast sample exchange has become the bottleneck for such experiments. A micro-patterned chip has been developed from single-crystalline silicon, which acts as a sample holder for up to several thousand microcrystals at a very low background level. The crystals can be easily loaded onto the chip and excess mother liquor can be efficiently removed. Dehydration of the crystals is prevented by keeping them in a stream of humidified air during data collection. Further sealing of the sample holder, for example with Kapton, is not required. Room-temperature data collection from insulin crystals loaded onto the chip proves the applicability of the chip for macromolecular crystallography. Subsequent structure refinements reveal no radiation-damage-induced structural changes for insulin crystals up to a dose of 565.6 kGy, even though the total diffraction power of the crystals has on average decreased to 19.1% of its initial value for the same dose. A decay of the diffracting power by half is observed for a dose of D1/2 = 147.5 ± 19.1 kGy, which is about 1/300 of the dose before crystals show a similar decay at cryogenic temperatures.	Jun 2016
I02-Macromolecular Crystallography I24-Microfocus Macromolecular Crystallography	A micro-patterned silicon chip as sample holder for macromolecular crystallography experiments with minimal background scattering Philip Roedig , Ismo Vartiainen , Ramona Duman , S. Panneerselvam , N. Stübe , Olga Lorbeer , Martin Warmer , Geoff Sutton , Dave Stuart , E. Weckert , C. David , Armin Wagner , Alke Meents Scientific Reports 5 DOI: 10.1038/srep10451 PMID: 26022615 Open Access Show Abstract ▼ Abstract: At low emittance synchrotron sources it has become possible to perform structure determinations from the measurement of multiple microcrystals which were previously considered too small for diffraction experiments. Conventional mounting techniques do not fulfill the requirements of these new experiments. They significantly contribute to background scattering and it is difficult to locate the crystals, making them incompatible with automated serial crystallography. We have developed a micro-fabricated sample holder from single crystalline silicon with micropores, which carries up to thousands of crystals and significantly reduces the background scattering level. For loading, the suspended microcrystals are pipetted onto the chip and excess mother liquor is subsequently soaked off through the micropores. Crystals larger than the pore size are retained and arrange themselves according to the micropore pattern. Using our chip we were able to collect 1.5 Å high resolution diffraction data from protein microcrystals with sizes of 4 micrometers and smaller.	May 2015
I24-Microfocus Macromolecular Crystallography	Structure determination from a single high-pressure-frozen virus crystal Anja Burkhardt , Armin Wagner , Martin Warmer , Rudolph Reimer , Heinrich Hohenberg , Jingshan Ren , Elizabeth E. Fry , David I. Stuart , Alke Meents Acta Crystallographica Section D Biological Crystallography 69, 308 - 312 DOI: 10.1107/S090744491204543X PMID: 23385466 Show Abstract ▼ Abstract: Successful cryogenic X-ray structure determination from a single high-pressure-frozen bovine enterovirus 2 crystal is reported. The presented high-pressure-freezing procedure is based on a commercially available device and allows the cryocooling of macromolecular crystals directly in their mother liquor without the time- and crystal-consuming search for optimal cryoconditions. The method is generally applicable and will allow cryogenic data collection from all types of macromolecular crystals.	Feb 2013
I04-1-Macromolecular Crystallography (fixed wavelength) I24-Microfocus Macromolecular Crystallography	Fast high-pressure freezing of protein crystals in their mother liquor Anja Burkhardt , Martin Warmer , Saravanan Panneerselvam , Armin Wagner , Athina Zouni , Carina Gloeckner , Rudolph Reimer , Heinrich Hohenberg , Alke Meents Acta Crystallographica Section F Structural Biology And Crystallization Communications 68 (4), 495-500 DOI: 10.1107/S1744309112009670 PMID: 22505429 Show Abstract ▼ Abstract: High-pressure freezing (HPF) is a method which allows sample vitrification without cryoprotectants. In the present work, protein crystals were cooled to cryogenic temperatures at a pressure of 210 MPa. In contrast to other HPF methods published to date in the field of cryocrystallography, this protocol involves rapid sample cooling using a standard HPF device. The fast cooling rates allow HPF of protein crystals directly in their mother liquor without the need for cryoprotectants or external reagents. HPF was first attempted with hen egg-white lysozyme and cubic insulin crystals, yielding good to excellent diffraction quality. Non-cryoprotected crystals of the membrane protein photosystem II have been successfully cryocooled for the first time. This indicates that the presented HPF method is well suited to the vitrification of challenging systems with large unit cells and weak crystal contacts.	Apr 2012
	Origin and temperature dependence of radiation damage in biological samples at cryogenic temperatures Alke Meents , Sascha Gutmann , Clemens Schulze-briese , Armin Wagner Proceedings Of The National Academy Of Sciences 107 (3), 1094-1099 DOI: 10.1073/pnas.0905481107 Show Abstract ▼ Abstract: Radiation damage is the major impediment for obtaining structural information from biological samples by using ionizing radiation such as x-rays or electrons. The knowledge of underlying processes especially at cryogenic temperatures is still fragmentary, and a consistent mechanism has not been found yet. By using a combination of single-crystal x-ray diffraction, small-angle scattering, and qualitative and quantitative radiolysis experiments, we show that hydrogen gas, formed inside the sample during irradiation, rather than intramolecular bond cleavage between non-hydrogen atoms, is mainly responsible for the loss of high-resolution information and contrast in diffraction experiments and microscopy. The experiments that are presented in this paper cover a temperature range between 5 and 160 K and reveal that the commonly used temperature in x-ray crystallography of 100 K is not optimal in terms of minimizing radiation damage and thereby increasing the structural information obtainable in a single experiment. At 50 K, specific radiation damage to disulfide bridges is reduced by a factor of 4 compared to 100 K, and samples can tolerate a factor of 2.6 and 3.9 higher dose, as judged by the increase of Rfree values of elastase and cubic insulin crystals, respectively.	Jan 2010
	Reduction of X-ray-induced radiation damage of macromolecular crystals by data collection at 15 K: a systematic study Alke Meents , Armin Wagner , Roman Schneider , Claude Pradervand , Ehmke Pohl , Clemens Schulze-briese Acta Crystallographica Section D Biological Crystallography 63 (3), 302-–309 DOI: 10.1107/S0907444906053261 PMID: 17327667 Show Abstract ▼ Abstract: The cryocooling of protein crystals to temperatures of around 100 K drastically reduces X-ray-induced radiation damage. The majority of macromolecular data collection is therefore performed at 100 K, yielding diffraction data of higher resolution and allowing structure determination from much smaller crystals. However, at third-generation synchrotron sources radiation damage at 100 K still limits the useful data obtainable from a crystal. For data collection at 15 K, realised by the use of an open-flow helium cryostat, a further reduction of radiation damage is expected. However, no systematic studies have been undertaken so far. In this present study, a total of 54 data sets have been collected from holoferritin and insulin crystals at 15 and 90 K in order to identify the effect of the lower data-collection temperature on the radiation damage. It is shown that data collection at 15 K has only a small positive effect for insulin crystals, whereas for holoferritin crystals radiation damage is reduced by 23% compared with data collection at 90 K.	Mar 2007

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