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Distinct Orientations (distinct + orientation)

Distribution by Scientific Domains

Chemistry	33%

Selected Abstracts

Functional implications of pigments bound to a cyanobacterial cytochrome b6f complex

FEBS JOURNAL, Issue 2 2005
Stephan-Olav Wenk
A highly purified cytochrome b6f complex from the cyanobacterium Synechocystis sp. PCC 6803 selectively binds one chlorophyll a and one carotenoid in analogy to the recent published structure from two other b6f complexes. The unknown function of these pigments was elucidated by spectroscopy and site-directed mutagenesis. Low-temperature redox difference spectroscopy showed red shifts in the chlorophyll and carotenoid spectra upon reduction of cytochrome b6, which indicates coupling of these pigments with the heme groups and thereby with the electron transport. This is supported by the correlated kinetics of these redox reactions and also by the distinct orientation of the chlorophyll molecule with respect to the heme cofactors as shown by linear dichroism spectroscopy. The specific role of the carotenoid echinenone for the cytochrome b6f complex of Synechocystis 6803 was elucidated by a mutant lacking the last step of echinenone biosynthesis. The isolated mutant complex preferentially contained a carotenoid with 0, 1 or 2 hydroxyl groups (most likely 9- cis isomers of ,-carotene, a monohydroxy carotenoid and zeaxanthin, respectively) instead. This indicates a substantial role of the carotenoid , possibly for strucure and assembly , and a specificity of its binding site which is different from those in most other oxygenic photosynthetic organisms. In summary, both pigments are probably involved in the structure, but may also contribute to the dynamics of the cytochrome b6f complex. [source]

Tailoring visual images to fit: Value creation in persuasive messages

EUROPEAN JOURNAL OF SOCIAL PSYCHOLOGY, Issue 2 2010
Lucia Mannetti
The present studies aimed to extend Regulatory Fit Theory in the domain of persuasive communication by (a) using printed advertisement images without any verbal claim, instead of purely or mostly verbal messages; (b) selecting the images to fit the distinct orientations of regulatory mode rather than regulatory focus; and (c) priming regulatory mode orientation instead of relying on chronic prevalence of either locomotion or assessment orientation. We found that recipients primed with a locomotion orientation experienced fit, and were more persuaded, when exposed to "dynamic" versus "static" visual images; conversely, recipients primed with an assessment orientation experienced fit and were more persuaded when exposed to "static" versus "dynamic" images. Our findings show that the experience of fit can be induced by visual messages, resulting in positive effects in terms of attitude toward product advertisement and estimated price of advertised products. Copyright © 2010 John Wiley & Sons, Ltd. [source]

Molecular mechanism of ubiquitin recognition by GGA3 GAT domain

GENES TO CELLS, Issue 7 2005
Masato Kawasaki
GGA (Golgi-localizing, ,-adaptin ear domain homology, ARF-binding) proteins, which constitute a family of clathrin coat adaptor proteins, have recently been shown to be involved in the ubiquitin-dependent sorting of receptors, through the interaction between the C-terminal three-helix-bundle of the GAT (GGA and Tom1) domain (C-GAT) and ubiquitin. We report here the crystal structure of human GGA3 C-GAT in complex with ubiquitin. A hydrophobic patch on C-GAT helices ,1 and ,2 forms a binding site for the hydrophobic Ile44 surface of ubiquitin. Two distinct orientations of ubiquitin Arg42 determine the shape and the charge distribution of ubiquitin Ile44 surface, leading to two different binding modes. Biochemical and NMR data strongly suggest another hydrophobic binding site on C-GAT helices ,2 and ,3, opposite to the first binding site, also binds ubiquitin although weakly. The double-sided ubiquitin binding provides the GAT domain with higher efficiency in recognizing ubiquitinated receptors for lysosomal receptor degradation. [source]

Keto-enol tautomerism in linear and cyclic ,-diketones: A DFT study in vacuo and in solution

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 10 2008
Giuliano Alagona
Abstract DFT geometry optimizations have been performed at the B3LYP/6-31G* level in the gas phase and at the IEF-PCM/B3LYP/6-31G* level in tetrahydrofuran (THF) and aqueous solutions using scaled radii for the diketo and ketoenol forms of acetylacetone and cyclohexanedione. To evaluate basis set effects, starting from the aforementioned minima, the 6-311++G** optimized structures have been obtained. A number of complexes of both systems including one explicit water molecule have been considered up to the B3LYP/6-311++G** level, for cyclohexanedione taking into account the B3LYP/6-31G* basis set superposition errors as well. The diketo,ketoenol interconversion mechanisms have been investigated at the B3LYP/6-31G* level in vacuo. Interestingly, the geometric constraint due to the presence of the ring facilitates the description of the reaction mechanism in cyclohexanedione. Despite the very different flexibility of the two systems that in the case of acetylacetone prevents a straightforward interconversion of the diketo to the most stable of its ketoenol forms, both reactions occur with a very high barrier (about 62,63 kcal/mol), unaffected by continuum solvents, that decreases by 2.5,3.5 kcal/mol after the inclusion of thermal corrections. The barriers are almost halved, becoming ,31,35 kcal/mol, for the addition of a single water molecule according to various model reaction paths. Thermal corrections are limited (0.8,1.6 kcal/mol) for those adducts. The formation of a 1,1-diol, explored in the case of acetylacetone, might facilitate the obtainment of the most stable diketo conformation, featuring the carbonyl groups in distinct orientations. Inclusion of dispersion and basis set effects via the G2MP2 protocol does not alter the relative stability of both system tautomers. In contrast, the G2MP2 interconversion barriers for the isolated systems in vacuo are close to the B3LYP ones, whereas they turn out to be somewhat higher than the free energy-based B3LYP barriers in the presence of a catalytic water molecule. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008 [source]

Do wavelets really detect non-Gaussianity in the 4-year COBE data?

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2000
P. Mukherjee
We investigate the detection of non-Gaussianity in the 4-year COBE data reported by Pando, Valls-Gabaud & Fang, using a technique based on the discrete wavelet transform. Their analysis was performed on the two DMR faces centred on the North and South Galactic poles, respectively, using the Daubechies 4 wavelet basis. We show that these results depend critically on the orientation of the data, and so should be treated with caution. For two distinct orientations of the data, we calculate estimates of the skewness, kurtosis and scale,scale correlation of the corresponding wavelet coefficients in all of the available scale domains of the transform. We obtain several detections of non-Gaussianity in the DMR-DSMB map at greater than the 99 per cent confidence level, but most of these occur on pixel,pixel scales and are therefore not cosmological in origin. Indeed, after removing all multipoles beyond ,=40 from the COBE maps, only one robust detection remains. Moreover, using Monte Carlo simulations, we find that the probability of obtaining such a detection by chance is 0.59. We repeat the analysis for the 53+90 GHz coadded COBE map. In this case, after removing ,>40 multipoles, two non-Gaussian detections at the 99 per cent level remain. Nevertheless, again using Monte Carlo simulations, we find that the probability of obtaining two such detections by chance is 0.28. Thus, we conclude the wavelet technique does not yield strong evidence for non-Gaussianity of cosmological origin in the 4-year COBE data. [source]

"Publics" Administration and the Ethics of Particularity

PUBLIC ADMINISTRATION REVIEW, Issue 5 2003
F. Neil Brady
Ethical orientations that emphasize universal duties, ideals, and values are well known to public administrators. We pay attention to principle, policy, ideals, shared goals, and the provision of a variety of commonly held values, such as clean air and water, mosquito abatement, and public recreation. The word "public" often seems to be a synonym for "universal." However, this article explores particularity in ethics, especially as it applies to the life of the public servant. It identifies three distinct orientations that focus on the concrete,as opposed to the abstract,and it shows how the exceptional cases are not administrative problems; rather they provide a reality check for public administrators who suppose rules, plans, and programs to be their primary orientation toward the management of public concerns. [source]