1,721,020 research outputs found
Sensitivity-Enhanced Four-Dimensional Amide–Amide Correlation NMR Experiments for Sequential Assignment of Proline-Rich Disordered Proteins
Full text linkProline
is prevalent in intrinsically disordered proteins (IDPs).
NMR assignment of proline-rich IDPs is a challenge due to low dispersion
of chemical shifts. We propose here new sensitivity-enhanced 4D NMR
experiments that correlate two pairs of amide resonances that are
either consecutive (NHi–1, NHi) or flanking a proline at position i–1 (NHi–2, NHi). The maximum 2-fold enhancement of sensitivity
is achieved by employing two coherence order-selective (COS) transfers
incorporated unconventionally into the pulse sequence. Each COS transfer
confers an enhancement over amplitude-modulated transfer by a factor
of √2 specifically when transverse relaxation is slow. The
experiments connect amide resonances over a long fragment of sequence
interspersed with proline. When this method was applied to the proline-rich
region of B cell adaptor protein SLP-65 (pH 6.0) and α-synuclein
(pH 7.4), which contain a total of 52 and 5 prolines, respectively,
99% and 92% of their nonprolyl amide resonances have been successfully
assigned, demonstrating its robustness to address the assignment problem
in large proline-rich IDPs
Measurement of Magnitude and Sign of H,H-Dipolar Couplings in Proteins
No full textMeasurement of Magnitude and Sign of H,H-Dipolar
Couplings in Protein
Hypalocrinins, Taurine-Conjugated Anthraquinone and Biaryl Pigments from the Deep Sea Crinoid <i>Hypalocrinus naresianus</i>
Full text linkFive new water-soluble amido- and
aminoanthraquinone pigments,
hypalocrinins A–E (1–5), the
new amidoanthraquinone biaryls hypalocrinin F (6) and
hypalocrinin G (7), and the known compounds 6-bromoemodic
acid (8), crinemodin (9), and crinemodin
sulfate (10) were isolated from the deep sea crinoid Hypalocrinus naresianus collected off Japan. The structures
of the compounds were elucidated by NMR spectroscopy and mass spectrometry.
Amido- and aminoquinones are quite unusual among natural products.
The hypalocrinins are the first naturally occurring anthraquinones
and anthraquinone biaryls conjugated with taurine
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Interdomain Dynamics via Paramagnetic NMR on the Highly Flexible Complex Calmodulin/Munc13‑1
No full textParamagnetic NMR constraints are very useful to study
protein interdomain
motion, but their interpretation is not always straightforward. On
the example of the particularly flexible complex Calmodulin/Munc13-1,
we present a new approach to characterize this motion with pseudocontact
shifts and residual dipolar couplings. Using molecular mechanics,
we sampled the conformational space of the complex and used a genetic
algorithm to find ensembles that are in agreement with the data. We
used the Bayesian information criterion to determine the ideal ensemble
size. This way, we were able to make an accurate, unambiguous, reproducible
model of the interdomain motion of Calmodulin/Munc13-1 without prior
knowledge about the domain orientation from crystallography
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