Beamline diagnostics for protein crystallography using synchrotron radiation

Beam diagnostics devices are described for the monitoring of all basic parameters relevant to protein data collection using synchrotron radiation. The parameters include the total power in the white beam, the positions and directions of the incident white and monochromatic beams, and the intensity, wavelength, and polarization in the incident monochromatic beam. Such devices have been installed on a doubly focusing wiggler beamline, BW6, at DORIS. They assure high quality in protein data collection despite fluctuations in the beam, facilitate rapid alignment of the entire beamline, and provide a basis for automatic realignment of the diffraction setup and the x‐ray optics

Synchrotron Radiation Mechanical properties of cellulose fibres and wood. Orientational aspects in situ investigated with synchrotron radiation

Highly oriented native cellulose fibres (flax) and softwood (pine) have been investigated by means of X-ray diffraction. Local structural information was obtained by using X-ray microbeams. Tensile tests were performed in situ, revealing a change of orientation of cellulose microfibrils in materials with tensile strain. In flax fibres, the microfibrils rotate during the first percent of stretching, into a more parallel orientation with respect to the fibre axis. For wood, a decrease of orientation with the onset of strain hardening is found for the first time

Cell-wall recovery after irreversible deformation of wood

Reseña evaluada por par académico sobre un libro de historia recientemente publicado.Book review (evaluated by an academic peer) about a History book recentely published

Elucidating the medium-resolution structure of ribosomal particles: an interplay between electron cryo-microscopy and X-ray crystallography

AbstractBackground: Ribosomes are the universal cellular organelles that accomplish the translation of the genetic code into proteins. Electron cryo-microscopy (cryo-EM) has yielded fairly detailed three-dimensional reconstructions of ribosomes. These were used to assist in the determination of higher resolution structures by X-ray crystallography.Results: Molecular replacement studies using cryo-EM reconstructions provided feasible packing schemes for crystals of ribosomes and their two subunits from Thermus thermophilus, and of the large subunits from Haloarcula marismortui. For the large subunits, these studies also confirmed the major heavy-atom sites obtained by single isomorphous replacement combined with anomalous diffraction (SIRAS) and by multiple isomorphous replacement combined with anomalous diffraction (MIRAS) at ∼10 Å. Although adequate starting phases could not be obtained for the small subunits, the crystals of which diffract to 3.0 Å, cryo-EM reconstructions were indispensable for analyzing their 7.2 Å multiple isomorphous replacement (MIR) map. This work indicated that the conformation of the crystallized small subunits resembles that seen within the 70S ribosomes. Subsequently, crystals of particles trapped in their functionally active state were grown.Conclusions: Single-particle cryo-EM can contribute to the progress of crystallography of non-symmetrical, large and flexible macromolecular assemblies. Besides confirming heavy-atom sites, obtained from flat or overcrowded difference Patterson maps, the cryo-EM reconstructions assisted in elucidating packing arrangements. They also provided tools for the identification of the conformation within the crystals and for the estimation of the level of inherent non-isomorphism

Metal Compounds as Tools for the Construction and the Interpretation of Medium-Resolution Maps of Ribosomal Particles

Procedures were developed exploiting organometallic clusters and coordination compounds in combination with heavy metal salts for derivatization of ribosomal crystals. These enabled the construction of multiple isomorphous replacement (MIR) and multiple isomorphous replacement combined with anomalous scattering medium-resolution electron density maps for the ribosomal particles that yield the crystals diffracting to the highest resolution, 3 Å, of the large subunit from Haloarcula marismortui and the small subunit from Thermus thermophilus. The first steps in the interpretation of the 7.3-Å MIR map of the small subunit were made with the aid of a tetrairidium cluster that was covalently attached to exposed sulfhydryls on the particle's surface prior to crystallization. The positions of these sulfhydryls were localized in difference Fourier maps that were constructed with the MIR phases

The identification of selected components in electron density maps of prokaryotic ribosomes at 7 Å resolution

Crystals of small and large ribosomal subunits from thermophilic and halophilic bacteria, diffracting to 3 Å, are being subjected to structural analysis with synchrotron radiation. The bright beam necessary for detecting and collecting the diffraction at the higher-resolution shell causes significant decay even at 25 K. Nevertheless, data collected from native and heavy-atom-derivatized crystals led to the construction of electron density maps of both ribosomal subunits, showing recognizable morphologies and internal features similar to those observed by EM reconstructions of the corresponding ribosomal particle. The main features of these maps include elongated dense regions traceable as well separated RNA duplexes or single strands. Also seen are globular patches of lower density, readily distinguishable from the above, in which folds observed by NMR or crystallography in isolated ribosomal proteins at atomic resolution were detected. The intercomponents contacts identified so far reveal diverse modes of recognition. Metal clusters, attached at selected sites on the particles, are being exploited to facilitate unbiased map interpretation. In this way, two surface proteins were located and several surface RNA strands were targeted

Lehr- und LernOrte vernetzen (Zwischenergebnisse des Futur.A-Projekts)

Das anwendungsbezogene Lernen hat für Studierende an Fachhochschulen eine hohe Bedeutung. Es übt nicht nur den Theorie-Praxis-Transfer in den angewandten Wissenschaften, sondern fördert unter persönlicher Anleitung auch motorische sowie interaktive Kompetenzentwicklung und nicht zuletzt die Motivation. Die Erweiterung von Lernumgebungen durch Digitalisierung solcher Lehrveranstaltungen erfordert eine besondere technische und didaktische Qualität, um Lernerfolge trotz der Nicht-Präsenz bestmöglich zu gewährleisten. Sie bietet jedoch auch neue Möglichkeiten für interdisziplinäres Lehren und Lernen. Das Futur.A-Projekt (Future Skills. Apllied) ist ein Verbundprojekt von sechs nieder-sächsischen Fachhochschulen und fokussiert im Teilprojekt 3 die Entwicklung, Erprobung und curriculare Verankerung digital gestützten anwendungsbezogenen Lernens. Erste Ergebnisse aus diesem Teilprojekt werden in diesem Band vorgestellt und beschrieben. Beispielhafte Lernorte sind Labore sowie Lehrveranstaltungen, in denen komplexe Themen mit starkem Anwendungsbezug behandelt werden