Dinesenperez7068

A fundamental prerequisite for implementing new procedures of atomic model refinement against neutron diffraction data is the efficient handling of hydrogen atoms. The riding hydrogen model, which constrains hydrogen atom parameters to those of the non-hydrogen atoms, is a plausible parameterization for refinements. This work describes the implementation of the riding hydrogen model in the Computational Crystallography Toolbox and in Phenix. Riding hydrogen atoms can be found in several different configurations that are characterized by specific geometries. For each configuration, the hydrogen atom parameterization and the expressions for the gradients of refinement target function with respect to non-hydrogen parameters are described. © 2020 Elsevier Inc. All rights reserved.Dynamic nuclear polarization (DNP) can provide a powerful means to amplify neutron diffraction from biological crystals by 10-100-fold, while simultaneously enhancing the visibility of hydrogen by an order of magnitude. Polarizing the neutron beam and aligning the proton spins in a polarized sample modulates the coherent and incoherent neutron scattering cross-sections of hydrogen, in ideal cases amplifying the coherent scattering by almost an order of magnitude and suppressing the incoherent background to zero. This chapter describes current efforts to develop and apply DNP techniques for spin polarized neutron protein crystallography, highlighting concepts, experimental design, labeling strategies and recent results, as well as considering new strategies for data collection and analysis that these techniques could enable. © 2020 Elsevier Inc. All rights reserved.The long-pulse spallation source of the European Spallation Source-a facility under construction in Lund, Sweden-is well suited for macromolecular crystallography experiments. We review briefly the particular properties of the long-pulse source and the associated high-brilliance moderators from the point of view of instrument design. We then outline the design philosophy and current design of the NMX macromolecular diffractometer. We also briefly describe the supporting facilities available for users and finish by an evaluation of the expected performance. © 2020 Elsevier Inc. All rights reserved.The IBARAKI Biological Crystal Diffractometer (iBIX) has been available for use at MLF (Material and Life Science Facility) in J-PARC (Japan Proton Accelerator Research Complex) since 2008. The development in state-of-the-art detector systems could enable iBIX to become one of the highest-performance neutron single-crystal diffractometers in the world. Here, together with other various developments, such as data reduction software, crystal growth, and new techniques in measurement coupled analysis, we provided new hydrogen and water structural data of several proteins and macromolecules. Although the proton power at MLF has not yet reached its planned maximum (1MW), a more powerful neutron source will be soon needed for neutron protein crystallography. A future idea is also proposed and discussed in this article. © 2020 Elsevier Inc. All rights reserved.This chapter introduces this topic for the whole volume. It is not a review, rather it presents the basics, the key considerations and forward references to the other chapters. This starts by setting the scene of principles and overall strategy, moves onto planning an experiment including its feasibility and then outlines practicalities with options for the experiment. The crystal structure that results will lead to publication and associated with it, Protein Data Bank deposition. © 2020 Elsevier Inc. All rights reserved.Voltage-dependent Ca2+ channels (Cavs) are indispensable for coupling action potentials with Ca2+ signaling in living organisms. The structure of Cavs is similar to that of voltage-dependent Na+ channels (Navs). It is known that prokaryotic Navs can obtain Ca2+ selectivity by negative charge mutations of the selectivity filter, but native prokaryotic Cavs had not yet been identified. We report the first identification of a native prokaryotic Cav, CavMr, whose selectivity filter contains a smaller number of negatively charged residues than that of artificial prokaryotic Cavs. A relative mutant whose selectivity filter was replaced with that of CavMr exhibits high Ca2+ selectivity. Mutational analyses revealed that the glycine residue of the CavMr selectivity filter is a determinant for Ca2+ selectivity. This glycine residue is well conserved among subdomains I and III of eukaryotic Cavs. These findings provide new insight into the Ca2+ selectivity mechanism that is conserved from prokaryotes to eukaryotes. plaore closely resemble the Cav-like channels thought to have existed in the common ancestor of bacteria and animals. Since other channel proteins from bacteria are useful genetic tools for studies in human and other animal cells, the Cav channel from M. ruber has the potential to be used to stimulate calcium signaling in experiments. © 2020, Shimomura et al.A native calcium ion channel has been identified in bacteria for the first time. © 2020, Suárez-Delgado and Islas.An osseous fragment at the distal tip of the medial malleolus in a skeletally immature individual may represent a secondary ossification center and should not always be interpreted as a fracture. Selleckchem PFK15 In this case study of a young dance student presenting with bilateral medial ankle pain, we postulated that hindfoot valgus, in combination with extreme loads placed on the foot during ballet training, increased stresses at the medial malleolus and accessory physis. Our patient was treated conservatively for symptomatic secondary ossification of medial malleolus and she returned to dance class at 6 months.In classical ballet, the execution of extreme movements on small bases of support causes the dancers constantly to seek balance. The objective of this systematic literature review was to evaluate the effects of classical ballet training on static and dynamic balance in order to emphasize the differences between dancers and non-dancers and between dancers with different levels of experience. Searches for scientific papers were conducted by two independent researchers in the PubMed, Science Direct, and LILACS databases. A secondary search was carried out by "snowballing" references in the selected studies. A modified Downs and Black checklist and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) scale were used to evaluate the methodological quality and evidence strength of the included studies, respectively. From 364 initial studies, nine were found to be eligible (five did analyses in static situations, two in dyna- mic situations, and two in both). With a maximum potential of 10 points, the methodological quality ranged from 6 to 8 on the Downs and Black checklist.