421 research outputs found
Time domain simulation of Gd3+-Gd3+ distance measurements by EPR
No full textGd3+-based spin labels are useful as an alternative to nitroxides for intramolecular distance measurements at high fields in biological systems. However, double electron-electron resonance (DEER) measurements using model Gd3+ complexes featured a low modulation depth and an unexpected broadening of the distance distribution for short Gd3+-Gd3+ distances, when analysed using the software designed for S=1/2 pairs. It appears that these effects result from the different spectroscopic characteristics of Gd3+ – the high spin, the zero field splitting (ZFS), and the flip-flop terms in the dipolar Hamiltonian that are often ignored for spin-1/2 systems. An understanding of the factors affecting the modulation frequency and amplitude is essential for the correct analysis of Gd3+-Gd3+ DEER data and for the educated choice of experimental settings, such as Gd3+ spin label type and the pulse parameters
W-band orientation selective DEER measurements on a Gd3+/nitroxide mixed-labeled protein dimer with a dual mode cavity
No full textDouble electron-electron resonance (DEER) at W-band (95 GHz) was applied to measure the distance between a pair of nitroxide and Gd3+ chelate spin labels, about 6 nm apart, in a homodimer of the protein ERp29. While high-field DEER measurements on systems with such mixed labels can be highly attractive in terms of sensitivity and the potential to access long distances, a major difficulty arises from the large frequency spacing (about 700 MHz) between the narrow, intense signal of the Gd3+ central transition and the nitroxide signal. This is particularly problematic when using standard single-mode cavities. Here we show that a novel dual-mode cavity that matches this large frequency separation dramatically increases the sensitivity of DEER measurements, allowing evolution times as long as 12 mu s in a protein. This opens the possibility of accessing distances of 8 nm and longer. In addition, orientation selection can be resolved and analyzed, thus providing additional structural information. In the case of W-band DEER on a Gd3+-nitroxide pair, only two angles and their distributions have to be determined, which is a much simpler problem to solve than the five angles and their distributions associated with two nitroxide spin labels. (C) 2012 Elsevier Inc. All rights reserved
Recommended from our members
Crossings ::how road ecology is shaping the future of our planet /
No full text"An eye-opening and witty account of the global ecological transformations wrought by roads, from an award-winning author. Some 40 million miles of roadways encircle the earth, but we tend to regard them only as infrastructure for human convenience. In Crossings, Ben Goldfarb delves into the new science of road ecology to explore how roads have transformed our world. Millions of animals are killed by cars each day in the US alone, and roads fragment wildlife populations into inbred clusters, disrupt migration for creatures from antelope to salmon, allow invasive plants to spread and even bend the arc of evolution itself. But road ecologists are also seeking innovative solutions: Goldfarb meets with conservationists building bridges for mountain lions and tunnels for toads, engineers deconstructing logging roads, and citizens working to undo the havoc highways have wreaked upon cities. A sweeping, spirited and timely investigation into how humans have altered the natural world, Crossings also shows us how to create a better future for all living beings" -
Embargo de beneficios previsionales en la República Argentina : teoría y práctica
No full textEl artículo analiza la cuestión del embargo de los beneficios previsionales en la República Argentina, considerando el marco teórico y sus aspectos prácticos. El autor revela la existencia de una incongruencia entre la prohibición legal de embargo (salvo los casos de excepción de deudas por alimentos) y la efectiva traba de medidas cautelares y ejecutivas por deudas
comunes.The article analyzes the question of the embargo of retirement benefits in the Argentine Republic, considering the theoretical framework and its practical aspects. The author reveals the existence of an inconsistency between the legal prohibition of embargo (except for cases of exceptions of maintenance debts) and the effective blocking of precautionary and executive
measures for common debts.Fil: Goldfarb, Mauricio. Universidad Nacional del Nordeste. Facultad de Derecho y Ciencias Sociales y Políticas; Argentina
High Field ENDOR as a Characterization Tool for Functional Sites in Microporous Materials
No full text
- …
